CA1045126A - Water soluble polymer esters and process for producing same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process is provided for preparing nitrate esters, or poly-meric sulfuric acid esters or salts thereof, or a mixed polymer nitrite sulfuric acid ester, or a polymer sulfuric acid ester, or a salt of a polymer sulfuric acid ester, from polymer nitrite. The polymer nitrite esters thus may be heated in the presence of nitric acid under specific conditions to form corresponding water soluble polymer nitrate esters.
Also, polymer sulfate ester salts may be prepared by sulfating the poly-mer nitrite ester to obtain the corresponding polymer nitrite sulfuric acid ester, reacting same with a protic solvent to obtain the polymer sulfate ester, and neutralizing or slightly alkalizing the polymer sul-fate ester reaction mixture with a base to produce the corresponding polymer sulfate ester salt.

Description

512~;
' The present invention relates to the use of nitrite esters in the preparation of other polymer derivatives, such as, for example, the lower substltuted nitrate esters and the sulfuric acid esters and their ; -salts.
This invention is a division of application Serial No. 143,874 filed June 5, 1972.
The polyhydroxypolymer nitrite esters are prepared according to the process disclosed and claimed in the above-identified parent ~-~
application by nitrosating the polyhydroxypolymer suspended in a suitable ' solvent at a temperature of 0 to 50C. As the nitrosating reagent, either dinitrogentetroxide, which is in equilibrium with its monomer, nitrogen dioxide, or nitrosylchloride is used. The usefulness of these -polymeric nitrite esters as intermediates in the preparation of other deriva~ives is demonstrated by a process according to an aspect of the present divisional application, namely, the preparation of the lower polymer nitrate esters and the sulfuric acid esters. The low D.S. nit-rate esters are obtained in a process according to an aspect of the ;
.
present divisional application simply by heating the corresponding ~
., ~ . .
~ nitrite esters in the presence of nitric acid under certain conditions ; ~: ~
and by subsequent treatment with a protic solvent. The preparation of ~-the sulfuric acid esters in a process according to an aspect of the .::.:.
present divisional application is carried out in three steps: (1) sulfa-tion of the~pol~ r nitrite ester to produce the mixed nitrite sulfuric acid ester; (2) removal of the residual nitrite groups by reaction of the mixed ester with a protic solvent; and (3) neutrali~ation of the polymer sulfuric acid ester with a suitabla base to produce the corres- - ~;
ponding salt. .
!
The polyhydroxypolymers useful according to the process dis-: , ::
;~ closed and claimed in the above-identified parent application include 30~ polysaocharides and synthetic polymers containing free hydroxyl groups, such as, for exa~ple, polyvinyl alcohols. These high molecular weight co~pounds contain 1 to 3 hydroxyl groups per polymer unit.
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Ester derivatives of polyhydroxypolymers are well kn~Jn and desc~ibed in numerous publications and patents. However, their chemical and physical properties depend greatly on the type and molecular weight of the polymer, their D.S., and on the tupe of substituent. Polymer nitrite esters, for example~ were previously unknown and are not ~; O
obtainable by known procedures. They are mo-;t valuable mainly because of the instability of their nitrite groups and, thus, their usefulness as intermediates in the preparation of other polymer derivatives accor-ding to processes of aspects of the invention in the present divisional application. The substitution of polyhydroxypolymers through their -nitrite esters as intermediates has great advantages and often results in derivatives which differ in their properties from those obtainable by prior art procedures. ~-For example, depolymerization, particularly that of polysac-charides, is negligible, and products with very high solution viscosities are obtained. Ih the case of sulfation, for example, polymer sulfate esters are obtained, the viscosities of which are many times greater than those of similar sulfate esters produced by prior art procedures. ;~
Additionally, it is possible to produce D.S. values which cannot be obtained by known procedures. Examples are the preparation of the cellulose sulfuric acid esters with a D.S. of one or less, and oE
the polymer nitrate esters with a D.S. of below 1. The latter results in water soluble nitrate esters (cellulose included) while the previously known polymer nitrate esters generally are highly sub~tituted and, there-fore, insoluble in water.
Another great advantage of derivatizing polyhydroxypolymers -; -over their nitrite esters iq the resulting uniform distribution of the substituents over the macromolecule. This comes as the result of the -~ .
fact that the polymer nitrite is solvated or :

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even dissolved in the reacti~n medium while, in prior art procedures,the polymer s.alting material is suspended in the medium in the form of insoluble particles. This is of importance especially in derivatives the D.S. pf which is considerably below the maximum, such as, for example, in the sulfate esters of one aspect of this invention, particularly the cellulose sulfate esters.
In the known sulfating procedures, for example, the insoluble cellulose fiber is used as the sta~ting material. Sulfation then occurs through the so-called "Peeling Processn, ~.e., 10 thé fiber sul-face is partially substituted, then solvated ~;
and removed by the reaction medium, and finally highly sub- ~
s~ituted by the excess reagent~ SubSequently, the next inner ` ;
layer of the fiber is exposed and sulfated in a similar , fashion. This process proceeds until either most of the fiber or the reagent is consumed. The polymer sulfate obtained generally is highly substituted, i.e., the D.S. is ~;
relatively ciose to the maximum, irrespective of the amount of reagent used. If, under certain conditions, somewhat lower ,~j, .,, . ~ .. ..
D.S. values are obtained, the distribution of the substituents is not uniform, i.e., a considerahle part of the polymer units is fully substituted while other units have a vexy low D.S. ox ~ -are not substituted at~all. In the process of an aspect of this invention, however, the 'lpeeling Process" is avoided, the polyhydroxy- ;
polymer is substituted under homogeneous conditions, and the substltuents are uniformly distributed. In the case of cellulose, it means that a product with a D.S. of ~ contains essentially only disulfate units and one with a D;S. of 1 contains essentially monosulfate units~ As a result, a number of further significant property differences becomes apparent when comparing products of an aspect of this invention with similar products obtained by prior art procedures. '.' ' One of these differences, or example, is the compatibility with certain metal salts. While aqueous solutions of all :, .,.:' ~ "
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~a4s~z6 cellulose sulfates of an aspect of this invention are compatihle with potassium, r~tbidium, calcium, strontium, chromium and other salts, and ~.
those of cellulose sulfates with a D.S. of 1.3 and lower are also com-patible with barium, cerous and ferric ions; proclucts with similar D.S.
but prepared by prior art procedures are incompatible even with rela-tively small a~ounts of a numb~r of such salts.
The initial starting compound of the process according to the ~ -invention of the above-identified parent application can be any suit~ble polyhydroxypolymer. Typical exa~ples of such compoun(ls are the poly-saccharides: cellulose, starch, hemicellulose, guar and locust bean gums, gum arabic and mannans; the polyuronic acids typified by alginic and '.~ -pectic acids, and the synthetic polyhydroxypolymers, such as, for example, polyvinyl alcohols. All of the foregoing compounds are readily r known in the art an~l all are available commercially.
The starting polyhydroxypolymer is suspended in a suitable O ~solvent including a swelling or solubilizing agent and a proton acceptor.
O~ n- Solvents found suitable for serving both of these functions include weak tertiary amine bases typified by pyridine, quinoline and isoquinoline, ¦
n _ and N,N-dialkyl acidamides such as, for example, N,N-dimethylformamide ~ I
and N,N-dimethylacetamide, hereinafter referred to as DMF and DMAC, res- ~ -pectively, and mixtures thereof. Suitable swelling or solubilizing agents are most solvents capab~e of dissolving polymeric esters, and typical examples are ethyl acetate, ethyl formate, benzene, acetone, - -~
methyl ethyl ketone and the like and mixtures thereof. Compounds suit-able as proton acceptors are those previously described as capable of providing both functions.
The amount of solvent used to suspend the polyhydro~ypolymer is not critical and may vary within a wide range; however, enough solvent should be used to avoid difficulty in handling the resulting ~ viscous mixture. Generally it has been found - ,: '~ - l :. .

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that a ~Lnimum amount of solvent to polymer ratio by weight is 3:1 respec-tively.
While a mlxture of proton acceptor-swelling agent and solvent is possible, it is preferred that a single solvent capable of perfornung both functions be usel to facilitate recovery and reuse thereof. However, should a nlxture be desired, it is necessary that the mixture contain at least 1 mole of proton acceptor to 1 mole of nitrosating oom~ound, as hereinafter described.
The first step of the process according to the invention of the above-identified parent application comprises nitrosating a polyhydroxy-polymer suspended in a suitable solvent with a compound selected from the group consisting of dinitro,gentetroxide, nitrosylchloride and mixtures thereof to obtain the corresponding polyhydroxypolymer nitrite ester. ,~
The nitrosating compound is used in the reaction mixture in a k Z n molar ratio of anhydroglucose or generally polymer unit to dinitrogentete-troxide or nitrosylchloride of 1:1, 2 or 3, resulting in D.S. of 1, 2 or 3 respectively. Since the reaction is quantitative, the D.S. approxImately ooincides with the molar amount of nitrosating agent used. If nitrosyl-chloride is used in combination with DMF or DM~C, a 2~5 to 3.0 fold excess of the reagent is required to attain these D.S.'s. Stated another ~ay, one mole of dinitrogentetroxide or nitrosylchloride is necessary to replace one mole of hydroxyl radical of the polyhydroxypolymer, and if nitrosyl-chloride is used with an N,N-dialkylacidamide as the proton acceptor, 2.5-3.0 m~les of nitrosylchloride are required.
- Ib clarify, the maxImum D.S. for hexosans, such as, for example, cellulose, starch, guar and locust bean gums, m~nnans, and thellike, is three; for pentosans such as, for example, hemecellulose and polyuronic acids, such as, ~or example, alginic and pectic acids is tWD; and ~or polyvinyl alcohols the maximum D.S. is ; ~ _ 5 _ ~............................................................. . .

1~)4S~6 one or less. Thus, the molar amount of dinitrogentetroxide necessary to obt~in complete esterification for hexosans is three moles per mole of anhydrohexo~e unit, for pentosans and polyuronic acids two moles per mole of anhydropentose or uronic acid unitsV and for polyvinyl alcohols one mole or less depending upon the degree of saponification of the starting compound. The same mole ratio amount of nitrosylchloride is necessary for complete esterifi-cation of such of the hereinbefore described classes of polyhydroxypolymer unless DMF or DMAC is used as the solvent, in which case the amount has to be substantially tripled.
An excess amount of the nitrosating compound beyond that necessary for complete esterification may be added with the only effect being an increased rate of esterification.
The reaction is preferably carried out with constant i agitation of the reaction mixture. It is necessary that the nitrosating compound be introduced into the polymer suspension under the exclusion of moisture. It is preferable to cool the reaction vessel in an ice bath, or the llke, since the reaction is moderately exothermic and it is necessary to stabilize the temperature of the reaction mîxture below 50 C., and preferably below 30 C.
I~ maximum esterification is desired, completenes~ of ..
the reaction is indicated by the formation of a clear solution or paste, while partial esterification is indicated by a -swelling and/or partial dissolving of the product in the reaction mixture~
The polymer nitrite esters are relatively sensitive -products and decompose immediately upon addition of a protic ;~
solvent, such as, for example,water, methanol, ethanol,-isopropanol, or the like in the presence of a mineral acid catalyst to regenerate the undegraded startinq polyhydroxypolymer. The regenerated ~"

~45~2f~ ~
compound is reco~Terable by filtration.
Since the polymtr n~trite esters produced according to the invention of the above-ldentified parent appllcation find their primary utility as intermediates for the production of other derivatives accor-ding to the process of aspects of the present divisional application, such as, for example, polymer nitrate and sulfate esters and the like, ' ~-there is no need to isolate them as t}le reaction mixture may be used for those processes, as hereinafter described. However, the polymer nitri.te esters may be isolatld by neutraliæing the reaction mixture by the addi- , tion of a base, such as, for example, mono~, di-, and trialkylamines, ~n pyridine, alkali or alkali earth metal hydroxides, carbonates, bicarbon-ates, or the like. The addition of such a base is necessary only if an N,N-dialkylacidamide had been used as the proton acceptor since, during nitrosation with dinitrogentetroxide or nitrosylchloride, an equimolar amount of nitric acid or hydrochloric acid is formed. If a weak tertiary amine base, such as, for example, pyridine or quinoline, had been used ~;
as the proton acceptor, the addition of a base is unnecessary since, then, the acid formed is neutralized by the tertiary amine base and cannot , serve as a catalyst for the decomposition of the polymer nitrite.
The neutralized, or preferably slightly a]kaline solution is then added to ice cold water with stirring to separate the polymer nit-rite ester as a fibrous material, which may be easily removed. Those products with a D.S. considerably below th~ maximum may be swellable or even soluble in water~ in which case an alcohol is used in place of ~ -:
the water.
The isolated product is relatively unstable and for storage purposes lt is preferred that lt be solvated in a suitable solvent such as, for exampIe, ben~ene, ethylacetate, ethylenedichloride, DMF~ DMAC~
or the like and stored at a low temperature, preferably below 10C.
~ The process according to one aspect of the present divisional x ;~
application col~rises heating the polymer nitrite ester solution in the ~ & ~ presence o~ nitric acid ~ 7 10~512~
with agitation at a temperature of 60-110C. for a period of 15 minutes .to two hours to obtain the corresponding polymer nitrate ester. -- Although the pplymer nitrate ester soluti~n according to one aspect of the present divisional application is generally the reaction mixture of step 1, in which DMF or DMAC has been used as the proton acceptor and dinitrogentetroxide as the reagent and in an amount sufficient for nitrosation to about the maximum D.S., the polymer nitrite ester may be isolated first then redissolved in one of the solvents as stated above and the corresponding amount of anhydrous nitric acid ` added. The use of the reaction mixture of step 1 for this:; ` .
step obviates the step of isolation of the polymer nitrite ester as hereinbefore described. Also, the addition of nitric acid is not necessary in this case since, during nitrosation with dinitrogentetroxide in DMF or DMAC, enough nitric , : .
acid is formed for the subsequent nitration.
It is preferred that the temperature of the heating step range from 80 to 100~ C. and the time of the heating step be from one-quarter to two hours. The D.S.
of the resulting polymer nitrate esters depends upon the reaction temperature and on the reaction time. Generally, the i--higher the temperature and the longer the time, the higher will . .
be the D.S. Thus, the D.S. of the resulting polymer nitrate esters will range from slightly above 0 to 0.6.~
;
The D.S. of the resulting polymer nitrate ester may be increased to 1.0 by the addition of an excess of anhyarous nitric acid and/or acetic anhydride to the reaction mixture prior - -~
to heating. It is preferred that the anhydrous nitric acid or acetic anhydride be added to the mixture in a range of 1 ~30 ~ to 10 moles per mole of polymer unit~
Subsequent to heating, the polymer nitrate ester is ~ -~
~ isolated by pouring the reaction mixture slowly and with ~
: ~ . ~,: .

.. ..

~ ~ i ~04~i~26 agitation into two or five volumes of a w.~ter miscible protic solvent, such as, for example, methanol, ethanol, isopropanol, and the like, which splits o~f residual nitrite groups and separates the resulting product. This product is then filtered off, washed with fresh solvent and dried.
; The resulting product is water soluble, and aqueous solutions ~, tolerate relatively high concentrations of water miscib:Le organic sol- ~`
vents such as, for example, the alcohols and ketones. Cellulose nitrate becomes water soluble if the D.S. exceeds 0.5. To illustrate, if the D.S. of the cellulose nitrate ester is lower than 0.5, the product can be highly hydrated but does not completely dissolve. Further, the sol~ltions of the polymer nitrate esters have a relatively high viscosity , and owing to their solubility or improved hydration in water and aqueous organic solvent, their usefulness is enhanced.
To form the polymer sulfate ester according to one aspect of the present divisional application, the procedure comprises sulfating the polymer nitrite ester solution, preferably with a sulfur trioxide solvent complex, at a low temperature to obtain polymer nitrite sulfuric acid ester.
The polymer nitrite ester solution preferably comprises the reaction mixture of step 1, in which a N,N-dialkylacidamide has been used as the prOtOnacceptor. The temperature of the reaction mixture must be maintained in the range from 0C. - 25C., and preferably 5 - 15C., to prevent dépolymerization of the molecule. --The preferred sulfating agent is sulfur trioxide which may be added to the reaction mixture in either its liquid or gaseous form or as a solution in an inert solvent such as, for example, carbon tetrachloride. ~ `
However, since the addition of sulfur trioxide is very e~othermic, and ~
.
the~low 9 . :

1~451Z~
t~m?~rature is critical to the viscosity of the desired product, it must be added slowly with st;rring, while maintaining the reaction mixture in a cooling medium such as, for exa~ple, an ice bath.
In practice, it is preferred that the sulfating agent be first added to a solvent, preferably the same solvent as contained in the reac-tion mixture to facilitate solven-t recovery, to form a cQ~plex which upon addition to the reaction mixture Eoxms a less exothermic reaction. Exam~
ples of solvents capable of forming a complex with sulfur trioxide are DMF, DM~C, dioxane and pyridine. Generally, the mole ratio of the sulfur triox-ide to the solvent in the complex is 1:1; however it is preferable to usean excess of the solvent to obtain a suspension or solution of the comr plex in the excess.
The complex is slowly added to the reaction nixture with agita-tion and exclusion of moisture. The am~unt of sulfating agent to be added to the nixture is dependent upon the D.S. desired of the resulting product.
A low D.S. value ranging between 0.1 to 1.0 requires 0.1 to 1.1 mole of sulfur trioxide per m3le of anhydroglucose unit. A D.S. value ranging from lo O to 2.0 is less quantitative and requires from 1.0 to 4.0 mole of sulfur trioxide per anhydroglucose unit. A. D.S. exceeding 2.0 is difficult under ;

the reaction conditions, and a large excess of sulfur trioxide required.
l~e addition of the sulfating agent to the p~lymer nitrite ester mixture forms a mixed polymer nitrite sulfuric and ester. Although the polymer nitrite ester with a maximum D.S. may be used for the sulfation, it is preferred to use the lower D.S. polymer nitrites particularly where a D.S. of above 1.1 is desired. ~nerally, the higher the degree of sulfa~ion . .
desired, the lower may be the degree of nitrosation such that the mixed , ,: -~.. .

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~045~26 polymer nitrite sulfuric acid ester has a maximum D.S. In other words, the sum of the degree of nitrosation and the degree of sulfation should be 3 for the hexosans, 2 for pentosans and polyuronic acids, and 1 or less for the polyvinyl alcohols.
The process according to one aspect of the present divisional application comprises reac~ing the mixed polymer nitrite sulfuric acid ester mixture with a protic solvent to obtain the corresponding polymer sulfuric acid ester.
The addition of a protic solvent such as, for example, water, methanol and ethanol results in the production of the pure polymer sul~
furic acid ester. The protic solvent replaces the nitrite groups of '' the product with hydroxyl groups and is added in stoichiometric amounts ~' -or an excess thereof. " ~ ' To isolate the'polymer sulfate ester product, two to four volumes of a water miscible solvent, i.e. acetone, is added to the mix-ture to separate the sulfated polymer therefrom. The ester is removed ~; ' and washed with fresh solvent, and redissolved in ice water. ; ' The process according to one aspect of the present divisional '~;' ' application comprlses neutralizing the polymer sulfuric acid ester with a base to form the salt thereof. ~`;
The isolated polymer sulfuric acid ester upon storage will `~ ' degrade and therefore it is preferable to convert it to the neutral salt. ' The preferred basis for neutralizing the sulfate ester are the hydroxides, carbonates and bicarbonates of the alkali and alkali earth metals, while ammonium hydroxide and the amines are likewise usable for this purpose.
Instead of neutralizing an aqueous solution of the isolated ~ ;
polymer sulfuric acid ester9 the polymer sulfuric acid ester-protic sol- ;~' vent reaction mLxture'of the process according to one aspect of the present divisional application may be neutralized directly to obtain the ~ '~
polymer sulfate ester salt. The base may be used as an aqueous solution or in its dry form. ~ ' ` . '', ' .,~

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10~5~LZ6 The resulting salt product is isolated by adding the neutralized mix~ure with agitation to a water miscible solvent such as, for example, acetone, methanol, ethanol, and isopropanol. The isolated product may be washed with aqueous solvent and de-hydrated with anhydrous solvent or vice versa. The separated . . ..
polymer sulfate ester salt is then removed and dried for storage.
The product is water soluble and since, during the reaction, depolymerization is negligible, a 1~ aqueous solution produces ~-~
a highly viscous solution. The sodium cellulose sulfate esters 0 ~ecome water soluble if the D.S. exceeds -c 0.3 and have viscosity measurement of as high as 8000-9000 cps.
As a result of this unique physical property, the products ``;-~
exhibit utility as thickening, suspending and emulsifying agents. -~
Generally, the viscosity decreases somewhat as the D.S; increases simply because of the additional weight to the polymer. However, in the application in bone glue it is preferred to use a product havlng a D.S. of 1.0 since i.. this particular use, best results are obtained with the higher D.S. products.
` The following examples illustrate specific preferred-embodiments ~;;
.0 according to the invention of the above-identified parent application and ~ according to the process of aspects of the present divisional application. -~
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11 ratios in ~he fol~owing examples~as well as in the specification and in the appended claims are by weight unles~ otherwise indicated. Te~pera- ~-tures are expressed in degrees cen~tigrade.

EXAMPLE I ~ ~
A. ~Preparation of Cellulose Nitrite Ester from Cellulose ;~ -, 20 g~. o~ Whatman cellulose powder, CF. II, was dried overnight at 110C. and placed in a three neck, round bottom flask equlpped with a mechanical~stirrer and calcium chloride ;
0 tube.; 200 ml. of N,N-dimethylformamide (DMF) was added to the ~ ~ : .. : . , cellulose powder and the mixture was stirred at room temperature.

With~exclusion of moisture, dinitrogentetroxide (N2O4) gas was . ~. .
~ -12~

`
10~5~Z6 slowly introduced to the mixture over a period of two hours.
It was observed that the mixture thickened with 7-8 g. of N2O4 and that a transparent viscous mixture without any i essential development of color was obtained upon introducing approximately 15g. of N2O4. After introduction of approximately 30g. of N2O4, the mixture formed a bluish green viscous solution, and on further addition of N2O4, the color became a deep green ;
while the viscosity appeared to remain constant.
To a sample of the three solutions r an excess of pyridine was added and the slightly alkaline mixture was poured with stirring into ice water. ~ fibrous precipitate was formed, -removed, washed with ice water and pressed out; and the -temperature was maintained at 0-5C. The fibrous precipitate of the first two samples was found to be swellable and that ` o the third sample was found to be soluble in common solvents for polymer esters including dimethylformamide, dimethylacetamide, benzene, acetone and ethylacetate. Upon attempting to dry the fibrous precipitate, the product decomposed as indicated by the release of brown fumes~ The resulting dried product was found /0. insoluble in the above described common polymer ester solvents. ~;
To identify the resultant products as cellulose nitrite esters and the degree of substitution or estexification (D.S.) thereof, the products were decomposed and cellulose and nitrous acid determinations were made. Products isolated from the above three solutions were washed with ice water and suspended ~ , . .
in distilled water in a closed Erlenmeyer flaskr acidified with sulfuric acid, and magnetically stirred at room temperature for 1 hr. The mixture was then neutralized with sodium hydroxide ~ and the insoluble cellulose was regenerated, filtered off, 0 washed with distilled water and dried in vacuo at 100 C. The 1 .
filtrate was collected for testing, as hereinafter `
described. ~
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10~5~LZ6 The identity of the regenerated cellulose was determined by comparison of the regenerated cellulose with the starting ; material by IR spectrophotometry, negative nitrogen analysis and found identical by the Xjeldahl method, and the absence of carboxyl groups as determined by the method of Samuelson and Wennerblom described in "Methods in Carbohydrate Chemistry", Vol. III Cellulose, 1963, p. 34.
To determine the lack of depolymerization of the molecule during the reaction and during storage of the reaction medium, `
0 thé viscosity of the regenerated cellulose from reaction mixtures kept over various periods of time, in cuprammonium hydroxide solution was compared with the viscosity of the starting -material in the same solution at an identical 0.5% concentration.
The viscosities were measured with a Cannon Fenske Viscometer at 25 C. The results of the tests are tabulated in the ; table below:
.. , . ~ .
Time and Tem~.
Materialof Storage Viscosity, Sec.
Starting Cellulose Control 28.8 Regenerated Cellulose6 hr. 5C. 27 0 Regenerated Cellulose30 hr. 5C. 28 8 Regenerated Cellulose120 hr. 5C. 28.3 j Regenerated Cellulose288 hr. 5C. 27~8 ~-J ~ The nitrite in the filtratb, as hereinbefore described, was determined by oxidation with permanganate solution to nitric acid. The presence of nitric acid subsequent to 1 oxidation was established by its determination as nitron : . .
nitrate according to the method of Hick described in Analyst, ;
Vol. 59, pp. 18-25 (1934). `
j~0 ~ ~The degrees of substitution were calculated from the weight of the cellulose and the amount of nitrous acid. The ~degrees of substitution calculated for the first solution con-talning 7 8 g. of N2O4 was 0.7; the second solution ' ' . ~ :
~ 14- ,, ~!-'" ' " ' :

~ iLSlZ6 containing 15 g. of N2O~ was 1.5 and for the third solution containing 30 g. of N2O4 was 2.8.
Results substantially similar to those obtained above are obtained when the following starting cellulose materiais are substituted for Whatman cellulose powder: cotton linter pulp, celluloses derived from wood or isolated from rice, corn, barley and oat hulls or from bagasse. However, if the ~ -foregoing starting materials are used, the amount of DMF used must be increased owing to the higher viscosities of the resulting products. Likewise, results similar to those obtained abo~e are obtained when the following solvents are substituted for N,N-dimethylformamide: N,N-dimethylacetamide, pyridine, quinoline, and mixtures thereof, or mixtures of one or more of the foregoing solvents and benzene, ethylacetate, or acetone. It was also found that the dinitrogentetroxide gas could be replaced by its liquid form or a solution thereof in one o~ thë above solvents and by nitrosylchioride to product substantially similar results.
B. Preparation of Cellulose Nitrate_Ester from Cellulose Nitrite Ester A dry 500 ml. three-neck, round bottom flask was charged with 9 g.of Whatman cellulose powder, CF II, suspended in 300 ml. of DMF and solubilized by adding approximately 15 g.
of dinitrogentetroxide gas to form cellulose nitrite ester.
The cellulose nitrite ester solution was mechanically stirred and heated at 90 C. for 50 minutes, poured slowly and with agitation into 6 volumes of methanol to form a precipitate, which was filtered, washed with methanol, and dried.
~ pon analysis the precipitate was found soluble in water~
and upon IR analysis showed a strong absorption peak at about 1680 cm~l, each test indicative of nitrate ester groups.
Nitrogen determinations by the Kjeldahl method indicated 10~5~26 :
the presence of nitrogen from which a 0.5 degree of substitution was calculated.
The addition of 15 g. of anhydrous nitric acid or 24 ml.
of acetic anhydride to the cellulose nitrite ester solution prior to heating revealed that the degree of substitution for the resulting cellulose nitrate ester was elevated to 0.8.
; Results substantially simila:r to those obtained above are obtained when DMF is substitu~ed by DMAC or by a mixture of DMF or DMAC and benzene.
~0 EXAMP~E II
A. Preparation of Hemicellulosie Nitrite Ester from Hemicellulose A SOO ml. three neck round bottom flask equipp~d with a mechanical stirrer and calcium chloride tube was charged with 40 g. of hemicellulose extracted from corn hulls and suspended in 300 ml. of DMF. The suspension was mechanically stirred and -` under the exclusion of moisture, 58 g~ of dinitrogentetroxide gas j was slowiy introduced to the mixture at room temperature to form a clear viscous solution of hemicellulose nitrite ester.
To a portion of the solution was added an-excess of ';. :.
~0 pyridine and the slightly alkaline solution was slowly poured with stirring into ice water to separate a fibrous precipitate.
The precipitate was removed, washed with ice water and pressed out.~ The resulting precipitate was found soluble in the common ;
polymer ester solvents described in Example lA. Upon drying, the precipitate decomposed releasing brown fumes.
Hemicellulose was regenerated for analysis by slowly adding a portion of the remaining hemicellulose nitrite ester ! solution to four volumes of methanol with agitation forming a ;~
precipitate which was filtered, washed with methanol, and dried.
~0 The;precipitate was identified as hemicellulose by IR spectro-. :. ;. .
photometry and by nagative nitrogen analysis by the Kjeldahl method.

:' . ', . ' . ~ ,; ~ ' 1a~451~ :
The lack of depolymerization of the regenerated hemi- ;
cellulose was determined by preparing 2~ aqueous solutions of the regenerated product and the starting material and adjusting the pH of the solutions to 6.7 with a dilute sodium hydroxide solution. The viscosities of the two solutions were measured with a Cannon Fenske Viscometer at 25 C. The viscosity of the regenerated hemicellulose was observed to be 138.5 sec. and the starting material 146.2 sec.
To identify the product as the nitrite ester and to determine the D.S., an excess of triethylamine was added to the reaction mixture and the sligh~ly alkaline solution was poured slowly and with stirring into ice water which resulted in the separation of hemicellulose nitrite ester. The hemicellulose nitrite was removed, suspended in water, and the mixture acidified with sulfuric acid and stirred for about 1 hour. Then, it was neutralized with sodium hydroxide and the neutral solution was added to 4 volumes of methanol, wherein ~ .
hemicellulose separated, and was removed, washed with methanol, dried and weighed.
The filtrate was collected, the methanol removed by concentration in ~acuo, and the resulting aqueous nitrite -solution was oxidized with a permanganate solution to form `
nitric acid, the presence of which was established by its determination as nitron nitrate according to the method of Hick~ described in Analyst, supra.
The degree o e substitu~ion was calculated by the weight of the hemicellulose and the amount of nitrous acid, and was `-., found to be 2Ø With less N2O4, the D.S. was correspondingly lower.
j ::
3 Results substantially similar to those obtained above are obtained when the following reagents are substituted for N,N-dimethylformamide: N,N-dimethylacetamide, pyridine, :~ , lO~:jlZ6 qulnoline and mixtures thereof, and mixtures of one or more of the above solvents and benzene, ethylacetate, or acetone.
Likewise, dinitrogentetroxide liquid or nitrosylchloride can be substituted for the dinitrogentetroxide gas to produce substantially similar results.
Hemicellulose nitrate ester is prepared from the hemi-cellulose nitrite ester in the same manner as related ~n Section B of Example I.

EXAMPLE III
A. ~E~aration of Starch Nitrite Ester from Pregelatini ed Starch A 500 ml. three neck round bottom flask equipped with a mechanical stirrer and calcium chloride tube.was charged with 40 g. of pregelatinized starch and suspended in 300 ml.
of DMF. Under exclusion of moisture, approximately 64 g.
of dinitrogentetroxide gas was slowly introduced to the mixture at room temperature and the mixture was mechanically stirred to form a clear viscous solution of starch nitrite ester.
To test the resulting solution, an excess of pyridine was added to a portion of the solution and the slightly alkaline mixture was slowly poured with stirring into ice water to ~ -separate a fibrous precipitate. The precipitate was removed, washed with ice water and pressed out. The resulting ~ -precipitate was found soluble in the common polymer ester solvents described in Example IA. Upon drying, the p~ecipitate :
decomposed releasing brown fumes, indicative of a nitrite. The l~ dried precipitate was again tested for its solubility, and found to be insoluble in the common polymer ester solvents.
Another portion of the starch nitrite ester solution was slowly added to four volumes of methanol with agitation, and the precipitate formed was filtered off, washed with methanol and dried. The precipitate was identified as starch by IR
spectrophotometry and by negative nitrogen analysis by the ---18- ~
,..;, ~O~ Z6 Xjeldahl method.
The lack of depolymerization of the regenerated starch was determined by preparing a 1% aqueous solution of the ~ -regenerated product and ~omparing its viscosity against the starting material. The solutions were adjusted to a pH of 6.0 with a dilute sodium hydroxide solution and the viscosities of the two solutions were measured with a Cannon Fenske Viscometer at 25 C. The viscosity of the regenerated starch was observed :, .
~o be 29.3 sec. as compared to 30.4 sec. for the starting material. -The product was identified as starch nitrite ester and ~
its D.S. determined by the method described under Example II , .
for hemicellulose. The degree of substitution was calculated by the weight of starch and the amount of nitrous acid, and found to be about 2.8. The D.S. was lower if a lower amount -of dinitrogentetroxide was used for nitrosation.
Results substantially similar to those obtained above are obtained when the following starting materials are substituted for the gelatinized starch: alginic acid, guar gum and locust bean gum. Likewise, N,N-dimethylacetamide, pyridine, quinoline and mixtures thereof, and mixtures of one or more of the above solvents and benzene, ethylacetate, or acetone may be substituted for N,N-dimethylformamide to obtain substantially the same results. Further nitrosylchloride, liquid dinitrogentetroxide, or a $olution of dinitrogentetroxide in one of the above solvents could be substituted for the dinitrogentetroxide gas and produce substantially similar results.
The starch and other polysacaharide ester solution was converted to the corresponding nitrate ester solution in a manner similar to Example IB.
. ""' ' . ''~ ' .. ' -19- ' .' ' .

~45~Z6 EXAMPLE IV
A. Preparation of Polyvinyl Nitrite Ester from Polyvinyl Alcohol To a dry 500 ml. three neck round bottom flask, 10 g.
of finely ground polyvinyl alcohol having a degree of saponifi-cation greater than 90% was suspended in 100 ml. of N,N-dimethyl-formamide. The mixture was mechanically stirred and under exclusion of moisture, dinitrogentetroxide gas was introduced.
The vessel was cooled with cold water to keep the temperature - at approximately 25 C. A cle~ar viscous solution was o~tained t 0 upon the addition of approximately 20 g. of dinitrogentetroxide gas.
Upon analysis, according to the methods described in Examples II and III, the~resulting product was identified as . polyvinyl nitrite ester having a degree of substitution of 0.8.
; It was found that when the polyvinyl alcohol starting material had a degree of saponification less than 90~,s~b.sT~nTiQ~y .~
the same result~ could be produced as obtained above, however the amount of dinitrogentetroxide gas required to solubilize the ~
starting material was less. ~ - -lo ,' The nitrite ester was converted to the nitrate ester , in a manner similar to Example IB.
- EXAMPLE V
Preparation of Sodium Alginic Acid Nitrate Ester - ' .:

2 g. of alginic acid was suspended in 80 ml. of DMF
and solubilized by 4.5 g. of dinitrogentetroxide gas according : . . . .
to the procedure of Example III. The solution was heated at 90 for 40 minutes and added slowly~ with agitation, to 3 volumes of ethanol to precipitate alginic acid nitrate ester.
The isolated precipitate was resuspended in water and neutralized with sodium hydroxide. The neutralized solution was then added slowly to 3 volumes of ethanol to precipitate ;
sodium alginate nitrate ester.

: : . -20-'' 10~51Z6 Results substantially similar to those obtained above are obtained when pectic acid is substituted for alginic acid.
The substitution of potassium hydroxide, calcium hydroxide, magnesium hydroxide and ammonium hydroxide for the sodium hydroxide results in the corresponding potassium, calcium, ~D ~magnesium and ammonium slats of the polyuronic nitrate estersO
EXAMPLE v:r A. Preparation of Cellulose Sulfuric Acid Ester 10 g. of cotton linter pulp having a high degree of poiymerization was suspended in 500 ml. of DMF and`reacted with dinitrogentetroxide to form the nitrite ester thereof with the maximum D.S. in accordance with Example lA. 40 ml~
; of DMF containing 3.5 g. of sulfu~ trioxide was:added to the nitrite ester mixture dropwise over a period of 40 minutes maintaining the temperature of the solution at 15 C., with ~igorous agitation to form a clear viscous solution. 20 ml.
of water was added to the viscous solution and it was then poured slowly and with vigorous agitation into 3 volumes of acetone to precipitate cellulose sulfurio acid ester, which precipitate was kneaded, washed with acetone, and redissolved in ice water. -B. Preparatlon of Sodium Cellulose Sulfate Ester The solution prepared in accordance with Example VI A
~ , . .
was neutralized by the addition of sodium hydroxide to a pH o 8.0 to form a clear viscous solution of sodîum cellulose sulfate ester. The clear solution was added slowly and w~th agitation to 3 volumes of acetone to precipitate and isolate the product. The precipitated product was kneaded, collected, washed with lresh acetone and dried. Upon analysis, the yield ~;
of sodium cellulose sulfate ester was 13.9 g. having a degree of substitution of 0.65, and a viscosity of 6500 cps. as a 1%
:
aqueous solution.

The viscosity was measured with a Brookfield Yiscometer, ~0~51~6 Model LVT, at 12 RPM and 25C. 1~ detennine the degree of substitution, a 0.4g. aliquot of the product was dissolved in 20% aqueous hydrochloric , acid and heated for 15 hours at 100c. A dark brown solution was fonT~d and filtered. ~rp the filtrate, an excess of barium acetate was added to precipitate sulfuric acid as barium sulfate. me barium sulfate was dried ~- and weiyhed and the deyree of substitution calculated therefrom.
Results substantially sirnilar to those obtained akove are o}~
tained when the cotton linter pulp starting material is replaced by cellu-lose fram other sources and/or having a lower deyree of polymerization, 10 ~ hernicellulose, starch, alginic acid, guar gum, locust bean yum and poly-vinyl alcohol. Other solvents capable of forming a calrplex with sulfur ;2 trioxide and which may be substituted for DMF in the DMF-sulfur trioxide ccq[ples are N,N~irnethylacetamide, pyridine, trialkylalr~ne, dirnethylsulfox-, ~ ide and dio~ane. Likewise, the sulfur trioxide -may be added to the solu-tion alone in the fonn of a liquid or a gas, or diluted with an inert sol-vent such as, for example, carkon tetrachloride though the reaction is -`
highly e~thermic and the use of an ice bath is necessary.
~en the ab~ve procedure was repeated and the ar~unt of sulfur ;~
, ~ .
' trioxide was reduced to 2.5 g., -the resulting product had a degree of sub-stitution of 0.5 and a viscosity of 6Q00 cps. I~e yield was reduced only ~ -, 20 --slightly to 13.4 g.
An irlcrease of the sulfur trio~ide to 4-5 g. and 6-7 g. resulted in D.S.'s of ~0.7-0.9 and 1.0-1.1 with viscosities of 6000-8000 cps. and 3000-4000 cps., respectively.
Similar results were obtained when cellulose nitrite ester with a D.S. of 2.4-2.5 was used.
D.S. values of 1.2-1.3 and 1.5-1.6 were obta~ned by using a cellu-l~se nitrite ester having à D.S. of 1.7-2.0 . .:
1 .

~0~15~26 ~ OD
and 1.4-1.6 and increasing the amount of sulfurtrioxide~
to 8-10 g. a~d 12.14 g., respectively. The viscosities~
of 1% aqueous solutions of the prod~icts were 1500-2000~c~s'~
and 800-1500 cps. respectively.
When cotton linter cellulose with a lower degree of polymerization was used, the D.S. 's were similar but the ~iscosities were correspondingly lower. Similarly, cellulose ` ~rom other sources generally produced products with lower viscosities.
o EXAMPLE VII
A. Thickened Rubbing Alcohol C~omposition ~; A thickened rubbing alcohol having the foilowing composition is prepared:
Component % by Weight Cellulose Nitrate Ester 5.0 ;
Water 25.0 Ethyl Alcohol 70.0~-The thickened rubbing alcohol exhibits a desired increased viscosity which tends to slow down evaporation of 0 the alcoholic solution, prolong skin contact and thereby aid - ;
absorption.
. . .
EXAMPLE VIII
A. Non-running Glue `~
.:
ComponentAmount by Weight ,! Bone Glue ' 150.0 g.
Sodium cellulose sulfate 5 g.
~` Water 1000 g.
'I ~ Thls improved glue exhibits a higher viscosity tending to retard running of the glue, particularly on vertical surfaces.

3 The particular composition exhibited a viscosity of 100 cps. at 25C. and 300 cps. at 50C.~and did not interfer or change the properties of the bonding glue.

~45~26 SUPPLEMENTARY DISCLOSURE
, - _ Ester deriva~ives of polyhydroxy polymers are known and have been described extensively in the prior art literature. The chemical and physical properties of such ester derivatives depend to a large ` extent on the particular nature of the polymer, its molecular weight, the type of ester substituent group, and the degree of substitution of - the polymer (hereinafter referred to as D.S.). Due to the manner in which ester derivatives of polyhydroxy polymers have previously been prepared, the D.S. of the resulting ester derivatives has not been rela- `
tively uniform. This has produced ester derivatives whose properties, , e.g. water solubility and compatability with various metallic ions, have no~ been generally satisfactory and has restricted the use areas for the .. . .
ester derivatives. ~ ~-In accordance with ~he invention as provided by aspects of the Principal Disclosure, it has been found that esterified polyhydroxy `
polymers having novel and unusual properties may be prepared from nitrite ~; ~
esters of the polyhydroxy polymers. The nitrite esters are employed in -;
the invention as provided by aspects of the Principal Disclosure as reac- ~
~, tion intermediates because of the instability of the nitrite ester groups ~;
and the solubility of the ester in the reaction medium. Through use of the nitrite ester intermediates, polymeric products, such as, for example, nitrate esters or sulfate esters of polyhydroxy polymers as provided by the process of aspects of the Principal Disclosure are obtained which -1~ have novel properties and a generally uniform substitution of nitrate , or sulfate ester groups among the polymer units. Due to the relati~e instability of the nitrite ester groups, polyhydroxy polymer nitrites may be used also for ma~ing films, fibers and other shaped articles con-sisting of homogeneous mixtures of various polyhydroxy polymers or of one or more polyhydroxy polymers~and one or more other polymers.
In the formation of an ester derivative of a polyhydroxy polymer I
as~provided by the process of aspects of the Principal Disclosure, the ~. 1 amount ~f depolymerization resulting from the reaction is negligible.

- SD 24 - `

-51~
Thus, products are obtai~ed which have very high solution viscosities.
In the case of sulfate esters of polyhydroxy polymers, for example, products have been obtained whose solution viscosities are many times greater than the solution viscosities of superficially similar sulfate esters produced by prior art methods.
In addition, it is possible accordin~ to the process of other aspects of the Principal Disclosure to produce esterified polyhydroxy polymers which have D.S. values that cannot be obtained by previously known methods. As an example, cellulose sulfate esters have been pre-pared having a low D.S., e.g. less than 0.3 in which the ester groupsare substantially uniformly distributed among the cellulose polymer units.
Also, sulfuric acid esters of locust bean gum and guar gum have been obtained which have a D.S. of above 1. Still 2urther, water soluble nit- -rate esters of polyhydroxy polymers have been prepared having a D.S. af less than 1. The properties of these nitrate esters are especially sur-prising since previous nitrate esters of polyhydroxy polymers have, in general, been highly substituted and insoluble in water. ~ ;
In addition, sulfate esters of polyhydroxy polymers as provided by the process cf aspects of the Principal Disclosure are also markedly different from superficially similar materials of the prior art in terms of their compatibilities with a wide variety of metallic ions and also their compatibilities with relatively high concentrations of metallic ions.
Still further differences are observed between the products of other aspects of the Principal Disclosure and superficially similar materials of the prior art, e.g., sulfates of polyhydroxy polymers, ln terms of reactivity with water soluble proteins.
~ As disclosed in the Principal Disclosure, one aspect of the present invention is directed to a process for the preparation of nitrate esters or sulfate esters of a polyhydroxy polymer which is a polysaccharide or a polyvinyl alcohol that is partially substituted with ether or ester groups. Etherified and esterified polysaccharides or ~polyvinyl alcohol~are known materials which may include, for example, ' ,: .

1045~Z6 substituent groups such as formate, acetate, carboxymethyl, methyl ether, ethyl ether, and propionate groups. Typical of the known etherified and esterified materials which may be employed as starting materials are carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulosé, alginic acid acetate, alginic acid propionate, starch phosphate, hydroxy-propyl guar, pectic acid butyrate, carboxymethyl starch, partially hydrolyzed polyvinyl acetate, natural sulfate esters such as, for example, carrageenan, natural acetyl esters, such as, for example, gum karaya and xanthan gum, etc.
In the formation of nitrate or sulfate esters of etherified or esterified polysaccharides or polyvinyl alcohol, as provided by the pro- ~ ~
cess of aspects of the Principal Disclosure, it is necessary that the ~;
reactant materials contain free hydroxyl groups. Thus, the etherified or esterified polysaccharide or polyvinyl alcohol used as the`starting material is only partially substituted and contains free hydroxyl groups which are utilized as reactant sites in accordance with tha invention.
The free hydroxyl groups on the etherified or esterified starting materials may, thus, be nitrosated~ nitrated and also sulfated in a ; ~-manner similar to the nitrosation, nitration, and sulfation of the unsubstituted polyhydroxy polymers to provide the corresponding ester ~`
derivatives of the partially etherified or esterified polyhydroxy poly-mers.
The nitrite esters of polyhydroxy polymers provided in appli~
cation Serial ~o. 143,874 filed June 5~ 1972 and from which the Principal Disclosure was divided employed as reaction intermediates in the process of other aspects of the Principal Dlsclosure are prepared by nitrosating a suspension of the desired polyhydroxy polymer starting material in a suitable organic solvent at a reaction temperature of below 50C. The nitrosating reactant is preferably dinitrogentetroxide which is in equilibrium with its monomer nitrogen dioxide. Through use of the ~-nitrite ester as a reaction intermediate, nitrate and suIfate esters of ::: :. .
polysaccharides and polyvlnyl alcohol can be readily synthesized in ;

"'~::
- SD 26 - ~
:: ::;' :' ""'' ~ .

!, ; . ,' . . , ", . ' ' ' ,.,. , . ', ' . ~ . ' . .

1045g~216 accordance with the process of other aspects of the Principal Disclosure.
The resulting nitrate and sulfate ester products show a negligible degree of depolymerization and a selective degree of esterification. Al~o, the nitrate and sulfate ester products are distinguished by their homogeneity of substitution, i.e.~ the ester groups, such as, for example, sulfate ester groups, are relatively ho geneously distributed over the macro-molecule. Thus, the properties of the products differ substantially from the properties of superficially similar products of the prior art in providing higher viscosities and in being compatible with certain metallic ions. ;
Water soluble nitrate esters may be easily prepared from the corresponding nitrite esters in accordance with the process of other aspects of the Principal Disclosure by simply heating the solvated nitrite esters in the presence of nitric acid and removal of residual nitrite groups by treatment with a protic solvent. The resulting nit-rate ester product is soluble in water, is relatively undegraded, and its aqueous solutions also tolerate relatively large amounts of water miscible organic solvents.
Polymeric sulfate esters are also prepared in accordance with ;
the process of other aspects of the Principal Disclosure by sulfatlng the nitrite ester of a polysaccharide or polyvinyl alcohol with sulfur trioxide or a complex thereof at a relatively low reaction temperatureO
Thereafter, residual nitrite ester groups are removed from the polymer ,;
by reaction with a protic solvent to provide a relatively undegraded polymeric sulfuric acid ester. The sulfuric acid ester may then be ., neutralized or made slightly alkaline to provide the more stable salt form of the e~ter. The undegraded alkali ester salts are highly soluble .
and their aqueous solutions possess a high viscosity. Thus, the sulfate ester salts are useful as thickeners in aqueous media.
As stated, when a nitrite ester is nitrated or sulfated in accordance with the process of other aspects of the Principal Disclosure, "!`~
the product which is obtained is a novel polysaccharide or polyvinyl ;~

~ .',.

~ S~L2S~
alcohol whi~h contains a mixture of nitrite ester groups with sulfate or nitrate ester groups with the mixture of groups being substantially uniformly distributed among the polymer units in the polysaccharide or polyvinyl alcohol. These novel products are valuable intermediates in the preparation of a sulfate or nitrate ester of a polysaccharide or polyvinyl alcohol in which the sulfate or nitrate ester groups are sub- -stantially uniformly distrihuted among the polymer units in the poly-saccharide or polyvinyl alchol.
As now provided by an aspect of the present Supplementary Dis-closure, the use of a nitrite ester of a polysaccharide or a polyvinyl alcohol as a starting material in the preparation of another ester of a polysaccharide or a polyvinyl alcohol is of particular importance in the preparation of novel cellulose sulfate esters. By controlling the degree of substitution of the nitrite ester of cellulose employed as the starting material, the degree of substitution of the cellulose sulfate product may be likewise controlled. Thus, when the nitrite ester of cellulose has a degree of substitutlon of 2 to 3; the cellulose sulfate ester which is produced in accordance with the invention has a degree of substitution ranging up to 1.1. However, when the nitrite ester of cellulose has a degree of substitution which is less than 23 the cellu-lose sulfate ester has a degree of substitution greater than 1.1. In each case, the sum of the degree of substitution of the cellulose sulfate ester and the degree of substitut-ion of the nitrite ester is equal to 3Ø
Thus, by one aspect of this invention as now provided by an :: ...
aspect of the present Supplementary Disclosure, a process is provided ;: .: .
for preparing a nitrate ester of a polyhydroxy polymer which is a poly-saccharide or a polyvinyl alcohol that is partially substituted with ether or ester groups. The process comprises reacting a nitrite ester :-. : .
~ of the partially substituted polyhydroxy polymer with nitric acid at a temperature of 60 to 110C. followed by treatment with a protic solvent to remove residual nitrite groups.
:. ~ , . . . . . .
A furthcr aspect of the invention as now provided by an aspect , ~ ' , - SD 28 - ~

5~Z~ :
of the present Supplementary Disclosure concerns novel water soluble sulfate esters of cellulose which have a degree of substitution of 0.3 to 1.0 with the sulfate ester groups being substantially uniformly dis-tributed among the polymer units of the cellulose. The water solubility -~of these materials is quite surprising since cellulose sulfate esters, as prepared by prior art methodsp are not water soluble unless the degree of substitution is in excess of 1Ø In the usage of these water soluble sulfate esters of cellulose, a further aspect of the invention as now . . .- ~ .
provided by an aspect of the present Supplementary Disclosure concerns ~ -a thickened aqueous medium which contains water and a water soluble sulfate ester of cellulose having a degree of substitution of 0.3 to 1.0 with the sulfate ester groups being substantially unlformly distributed among the polymer units of the cellulose and the cellulose sulfate ester being present in an effective amount to thicken the aqueous medium.
Thus, by another aspect of this invention as now provided by an aspect of the present Supplementary Disclosure a process is provided for preparing a sulfate ester of 8 polyhydroxy polymer which is a poly- -saccharide or a polyvinyl alcohol that is partially substituted with ether or ester groups. The process comprises reacting a nitrite ester of the partially substituted polyhydroxy polymer with sulfur trioxide or a complex thereof at a reaction temperature of 0 to 25C. to obtain a mixed nitrite:sulfate ester of the polyhydroxy polymer. The mixed ester is then reacted with a protic solvent to remove residual nitrite ester '' ::..::.
groups from the polymer and the polymer may be reacted with a base to ~;
neutralize or slightly alkal~ze the polymer and to obtain the sulfate ester in the form of an alkali or alkali earth metal salt. `' i., .. . :::, .
A still further aspect of the invention as now provided by an aspect of the present Supplementary Disclosure concerns water insoluble esters of cellulose which are9 howeverp highly swellable in the presence of water. These water insoluble ceIlulose sulfate esters have a degree of substitution of less than 0.3 with the sulfate ester groups being substantially uniformly distributed among the polymer units of the 51~6 cellulose. The water swellability o~ these materials is quite unusual.
Due to the unusual properties of the water swellable esters of cellulose having a D.S. less than 0.3, these materials have novel utilities in the preparation of absorbent materials, such as, for example, diapers, towels and the like.
Thus by yet another aspect of this invention as now provided by an aspect of the present Supplementary Disclosure, a process is pro vided for preparing a substantially uniformly substituted colloidal cellulose sulfate having a degree of substitution of 1.0 to 2.0 which is compatible with potassium ions in an aqueous medium without gellation of the cellulose sulfate and a significant increase in the viscosity of the aqueous medium. The process comprises reacting a nitrite ester of cellu-lose having a degree of substitution of 2 to 1 with sulfur trioxide or a complex thereof at a reaction tempera~ure of 0 to 25C. to obtain a mixed nitrite:sulfate ester of cellulose in wllich the sum of the degree of substitution of the nitrite ester groups and the degree of substitu-tion of the sulfate ester groups is equal to 3Ø The mixed ester is then reacted with a protic solvent to remo~e residual nitrite ester groups and the cellulose sulfuric acid ester may then be reacted with a base to neutralize or slightly alkalize the cellulose ester and to obtain ~
the cellulose ester in the form of its alkali or alkali earth metal salt. ;
A still further~aspect of the invention as now provided by an aspect of the present Supplementary Disclosure concerns novel water ~ ;
soluble nitrate esters of a polysaccharide or a polyvinyl alcohol having a degree o~ suhstitution of less than 1.0 in which the nitrate ester groups are substantially uni~ormly distributed among the polymer units of the polysaccharide or yolyvinyl alcohol. The properties of these ~ ' materials are unique in that nitrate esters produced bv prior art proce- -dures are highLy substituted and water insoluble.
Thus, by yet another aspect of this invention as now provided by an aspect o the present Supplementary Disclosure is provided contain-~, .
ing a nuxture of nitrite ester groups with sulfate or nitrate ester ~0~5il 26 groups with the mixture of ester groups being substantially uniformly distributed among the polyme~ units ~f the polysaccharide or polyvinyl alcohol.
By yet another aspect of this invention, as now prouided by an aspect of the present Supplementary Disclosure, a water soluble nitrate ester of a polysaccharide or a polyvinyl alcohol is provided, which ester has a degree of substitution of less than 1.0 with the nitrate ester groups being substantially uniformly distributed among the polymer units of the polysaccharide or polyvinyl alcohol.
As a corollary to the unique water soluble nitrate esters of a polysaccharide or a polyvinyl alcohol provided hërein, a further aspect of the invention as now provided by an aspect of the present Supplementary Disclosure concerns a thickened aqueous medium containing water and a water soluble nitrate ester, as described, having a degree of substitu-tion of less than 1Ø The nitrate ester groups are substantially uni-formly distributed among the polymer units of the polysaccharide or poly-vinyl alcohol and the water soluble nitrate ester is present in an effec-tive amount to thicken the aqueous medium.
Accordingly by another aspect of this invention as now provided by an aspect of t~e present Supplementary Disclosure a thickened aqueous medium is provided containing water and a water soluble nitrate ester of a polysaccharide or a polyvinyI aIcohol. The ester has a degree of substitution of less than 1.0 and the nitrate ester groups are substan-tlally uniformly distributed among the polymer units of the polysacchar-ide or polyvinyl alcohol with the water soluble nitrate ester being present in an effective amount tD thicken the aqueous medium.
..
By still another aspect of this invention as now provided by an aspect of the present Supplementary Disclosure, a water soluble sul-., :, fate ester of cellulose is provided having a degree of substitution of : ~ ~ '. ', , :
0.3 to 1.0 with the sulfate ester having a substantially uniform distribu- ~ ' tion of sulfate ester groups a n& the polymer units of the cellulose.
By yet another aspect of this invention as now provided by an ~' ,' .

10~126 aspect of the present Supplementary Disclosure, a thickened aqueous medium is provided containing water and a water soluble sulfate ester of cellulose having a degree of substitution of 0.3 to 1. The sulfate ester groups in the cellulose sulfate are substantially uniformly dis- -tributed among the polymer units of the cellulose and the cellulose sul-fate is present in an effective amount to thicken the aqueous medium.
By a still further aspect of this invention as now provided by an aspect of the present Supplementary Disclosure, a water insoluble sulfate ester of cellulose is provided which is highly swellable in the presence of water and has a degree of substitution of up to 0.3 with the sulfate ester groups being substantially uniformly distributed among the - -polymer units of the cellulose. ~;~
In a still further aspect of the inYention as now provided byan sspect of the present Supple~éntary Disclosure, it has been found that : : , .
the nitrite substituent groups present in nitrite esters of polyhydroxy polymers, e.g., cellulose, or in mixed nitrite:nitrate esters or nitrite:
sulfate esters of a polyhydroxy polymer are surprisingly labile. Thus, ;
unlike other nitrites, the nitrite substituent groups on the cellulose (or other polyhydroxy polymer) may be readily removed to form alkyl nitrites during formation of nitrate or sulfate esters of cellulose from cellulose nitrite esters with the alkyl nitrites being by-products to the .
formation of cellulose nitrate or cellulose sulfate esters.
In forming an alkyl nitrite ester as a by-product in accordance -with the invention as now provided by an aspect of the present Supple-mentary Disclosure, an alkyl alcohol is added to a reaction mixture con-taining a mixed nitrite:nitrate or a mixed nitrite:sulfate ester of a polysaccharide or a polyvinyl alcohol. Since the mixed ester i5 generally ., .,, . ,:
formed through addition of a nitrating or sulfating reagent, as described previously, to a reaction mixture formed in the production of the nitrite ester intermediate, dinitrogentetroxide may be liberated and be present ~
in the reaction mixture. When alkyl alcohol is added, the alcohol reacts -with both the free dinitrogentetroxide and the labile ni~rite groups on ~ ,.,: .

,~

1~5~;~6 the polysaccharide or polyvinyl alcohol. 1he reaction of the dinitro-gentetroxide with tl.e alkyl alcohol results in the formation of alkyl nitrite esters by a direct nitrosation which is comparable, in terms of mechanism, to reaction of dinitrogentetroxide with a polysaccharide or polyvinyl alcohol in forming the nitrite ester. However, reaction of the nitrite substituent grollps on the polysaccharide or polyvinyl alcohol with the alkyl alcohol occurs through a transesterification reaction rather than a direct nitrosation. Although not bound by any theory, it appears that the transesterification reaction favours the production of the most stable nitrite ester in the system which, in this particular case, is the alkyl nitrite which is produced quantitatively. -Whatever the reaction mechanism may be, lt is mos~ important that both the free dinitrogentetroxide and the nitrite substituent groups on the polysaccharide or polyvinyl alcohol quantitatively form the same alkyl nitrite product so that the excess dinitrogentetroxide enters into the production of the valuable by-product alkyl nitrite.
As a suitable alkyl alcohol, various alkanols and alkanediols may be used, such as, for example, propanol, butanol, amyl alcohol, ethanediol, 1,2-propanediol, etc. In addition, higher alcohols may be used such as,for example, decanol containing up to 10 carbon ato~s.
Primary alcohols, such as, for example, butanol, secondary alcohols, such `~
as, for example, isopropanol, and also tertiary alcohols~ such as, for example, tertiary butyl alcohol are equally suitable for the reactlon.
In order to utilize the dinitrogentetroxide reagent quantitatively in the :~
reaction, the alkyI alcohol reactant should be present in an amount of at ,.
least one mole of alkanol or bne-half mole of alkanediol for each mole of dinitrogentetroxide which i8 initially added in forming the nitrite ~ester of the polysaccharide or poIyvinyl alcohol intermediate with the alcohol being added after formation of the mixed polysaccharide or poly-v1nyl alcohol ester.

Since alkyl Ditrite esters are relatively stable in comparison to the nitrite esters of polysaccharides or pol)vinyl alcohol, the ~ ` :
5~26 further reaction steps in forming the primary nitrate or sulfate ester product, i.e., neutralization, separation and isolation of the resulting nitrate or sulfate ester of the polysaccharide or polyvinyl alcohol, can be carried out without first removing the alkyl nitrite ester. Thus, for example, in forming a mixed ni~rite: sulfuric acid ester of cellu-lose with subsequent addition of the required amount of alcohol, the resulting sulfuric acid ester of cellulose may be precipitated by addi- -tion of acetone to the reaction mixture followed by removal of the precipitate for further processing. The alkyl nitrite ester remains in the filtrate and both the solvents and the alkyl nitrite may be readily recovered by fractional distillation or any other suitable means. Since ~ ;
the filtrate is acidic, it may be neutralized with a suitable base prior to distillation to minimize decomposition of the various compounds. As an additional way to minimize decomposi~ion, the distillation may be carried out at a reduced pressure.
In separating the ester product, such as, for example, the sulfuric acid ester of cellulose, it is generally preferred to neutralize the entire reaction mixture without first isolating the ester product.
This provides a large saving in the amount of solvent which is used and no decomposition of the alkyl nitrite by-product has been observed when the product recovery is carried out in this manner. Thus, after addi~ion of the alkanol or alkanediol, a suitable base, such as, for example, the ammonium and~N-substituted ammonium, alkaIi, or alkaline earth hydroxides, carbonates, or bicarbonates is added as an aqueous solution or as a sus-.
pension of an excess quantity of base in its saturated solution with con-tinuous mixing of the reaction mixture during addition of the base. The preferred baees are the alkali carbonates and alkali bicarbonates which may be added also in the form of dry powders. To prevent any degradation of the polysaccharide ester product or polyvinyl alcohol ~ster product, ~ -e.g., the cellulose sulfate ester, the reaction mixture is preferably kept at a temperature of below 15 - 20C. until the neutralization is completed. `~

- SD 34 _ ,~ ' ,'".
, ~ID45~1LZ6 ~ If the solids concentration of the reaction mixture is suffi-ciently high and the concentrati~n ~f water in the mixture is relatively low, the cellulose sulfate ester may be present in a wet solid form and may be ~eadily removed. Ifl however, the cellulose sulfate ester is in the form of a paste after neutralization, a sufficient quantity of a water ~iscible solvent, such as, for example, acetone, methanol, ethanol9 or isopropanol, is added to cause separation so that the product can be removed, pressed out, and dried or purified further. If the product is dried directly, the resulting product ~s a technical, relatively crude 1~ grade product which contains salt as the principal impurity. A purified product may be prepared by extracting the wet solids one or more times with an aqueous alcohol, such as, for example, methanol, ethanol, or isopropanol containing 20 - 40 per cent by weigl-t of water, followed by drying of the product at an elevated temperature. Of course, it is also possible to extract the dried technical grade product with aqueous alcohol to arrive at a refined grade.
- The filtrate, as described above, may contain both solvents : , . . .
and also an alkyl nitrite and both the solvents and alkyl nitrite may be '~
easily recovered by distillation. If a higher alkyl nitrite, e.g., in ` , excess of 7 carbon atoms, is produced as a by-product which contains a relatively high number of carbon atoms, part of the higher alKyl nitrite ;~
may remain with the solids because of its reduced solubility in aqueous alcohol. In this event, a final extraction may be carried out with . .
anhydrous alcohol or with an alcohol containing less than--20% of water.

This wlll remove the higher alkyl nitrite more thoroughly and will .
result in obtaining higher yields during distillation. In addition, it is also possible to dry the solids in a closed system such that all ~,t ~ ~ ' absorbed solvents, including any retained alkyl nitrite, can be recovered.
Thus, as described above, by yet another aspect of this inven-tion as now provided by an aspect of the present Supplementary Disclosure, `~
a process is provided for simultaneously preparing a nitrate or sulfate ester of a polysaccharide or po~yvinyl alcohol and an alkyl nitrite. The ' : -; , , 10~51Z6 ~ ~rocess comprises reacting a nitrite ester of the polysaccharide or f ~ ~ Zpolyvinyl alcohol with nitric acid or sulfur trioxide or a complex thereof to obtain a mixed nitrite:nitrate or nitrtie:sulfate ester. The m ~ulfation or nitration reaction may liberate dini~rogentetroxide, and the mixed ester is th~n reacted with an organic alcohol containing up to 10 carbon atoms with the alcohol reacting with nitrite groups in the mixed ester and also with any dinitrogentetroxide tha-. is present to produce an alkyl nitrite product and while freeing the mi~ed ester of nitrite groups.
A second by-product which may be for~.ed in equivalent amounts is an inorganic nitrate, for example, sodium nitrate, if sodium hydrox-ide or sodium carbonate was used for neutralization. If lt is not desired that an alkyl nitrite ester be produced simultaneously with pro-duction of the inorganic nitrate, an equivalent amount of water may be added to the reaction mixture instead of adding an alkyl alcohol. This ~ ;
will then result in the formation of equivalent amounts of inorganic nitrate and nitrite, such as, for example, sodium nitrate and sodium nitrite. Both salts will be in the filtrate and will remain in the ~
residue after recovery of the solvents. The salts may be purified by ~ -crystallizatîon or other known methods to provide salts of medium or ~ -high purity. However, if the saIts are to be used as fertilizers, addi-tional purification may not be necessary. -;
Ihus, as described above, by yet another aspect of the inven-tion as now provided by an aspect of the present Supplementary Disclos-ure, a process is provided for simultaneously preparing a nitrate or eulfate ester of a polysaccharide or polyvinyl alcohol and an inorganic nitrate in conjunction with an alkyl nitrite or an inorganic nitrite.
. ..
The process comprises reacting a nitrite ester of the polysaccharide or polyvinyl alcohol with nitric acid or sulfur trioxide or a complex thereof to obtain a mixed nitrite:nitrate or nitrite:sulfate ester, and ;
then adding water and neutralizing with an inorganic base to provide a ;~
mixture of an inorganic nitrite and an inorganic nitrate as by-products . . ! :
':

~0~s~%6 along with tl-~ primary ester product. If an alcohol is added instead of water, the by-products will be a mixture of alkyl nitrite with an inorganic nitrate.
Now, as provided by this Supplementary Disclosure, cellulose, for example, can be easily sulfated to a D.S. of between 1 and 2 only when the degree of nitrosation is between 2 and lo However, if the degree of nitrosation drops considerably below 1, sulfation becomes increasingly more difficult and incomplete arld the distribution of the sulfate groups non-uniform.
As provided in the Principal Disclosure, the isolated poly-meric sulfuric acid ester will degrade upon storage and therefore it is preferable to convert it to a neutral salt. The preferred bases for ;
neutralizing the sulfate ester are the hydroxides, carbonates and bicar-bonates of the alkali and alkaline earth metals, while ammonium hydrox-ide and the amines are likewise usable for ~his purpose. Now as taught by the present Supplementary Disclosure, the resulting salt product is isolated by adding the neutralized mixture with agitation to a water miscible solvent such as, for example, acetone, methanol, ethanol, and isopropanol or vice versa. The lsolated product may be washed with an aqueous solvent and dehydrated by washing w~th anhydrous solvent. The ~ ~ -separated polymeric sulfate ester salt may then be removed and dried for ~storage.
As provided by the Principal Disclosure, instead of neutraliz-ing an aqueous solution of the isolated polymeric sulfuric acid ester, the polynteric sulfuric acid ester-protic solvent reaction mixture of the prevlous step may be neutralized directly to obtain the polymeric sul-fate ester salt. In this case, the base may be added as an aqueous soltl-tion or in its dry form. Now as taught in this Supplementary Disclosure, ln the neutrallzed mixture, the product may be present in wet, but solid, 3U fornt and ntay be removed directly by centrifugation or filtratio~, pressed out, and dried to obtain a technical grade product which contains salt ;
impurities. A pure grade or product is obtained by washing the wet :

- ~ - SD 37 -,, ,, I.

1~4~2~i :
product one or more times with aqueous alcohol prior to drying. If there is a relatively large amount of water in the neutralized mixture, the product may be too soft to be removed or it e~en may be partially dissolved. In this case, enough alcohol is added to harden the product somewhat or to precipitate it, so it can be filtered off or centrifuged.
The following examples illustrate specific preferred embodi-ments of various aspects of this invention. All ratios in the following exa~ples as well as in the specification and in the appended claims are by weight unless otherwise indicated, and temperatures are expressed in degrees centigrade.
Results substantially similar to those obtained in Example I
of the Principal Disclosure are obtained when DNF is substituted by D~AC
or by a mixture of DMF or DMAC and benzene or when methyl cellulose, carboxymethyl cellulose or carboxyethyl cellulose is used in place of cellulose. `-As taught in Example VI of the Principal Disclosure, an increase ;
of the sulfur trioxide to 4-5 g. and 6-7 g. resulted in D.S.'s of 0.7~0.9 -and 1.0-1.1 with viscosities of 6000-8000 cps. and 3000-4000 Cp8., res- ~ -pectively. However, as now provided by the present Supplementary Disclos- ;
ure, a further increase of ~he sulfur trioxide did not result in D.S. ''.. !':.'.~',,":,.. ~ "
values of much above 1.0-1.1 under these conditions. `7 Moreover, similar results were obtained with starch, guar and ~ -locust bean gu= , and with hemicellulose. Also, methyl cellulose with a D.S. of 1.0-1.5, carboxymethyl cellulose, hydroxy ethyl starch, acety-lated alginic and pectic acids (with a degree of acetylation of below `
1.5) and hydroxypropyl guar were found equally suitable for nitrosation and subsequent sulfation. However3 the amount of reagent necessary for full nitrosation was based only on the number of free hydroxyl groups.
EXAMPLE VII
:,. .:
Cellulose (25 g.) was suspended in 1000 ml. DMF and 38 g. N204 were introduced to obtain cellulose nitrite ester. A solution of a cal-culated amount of DMF-S03 complex in DMF was then slowly added with ~
'," ' "
:" '~'.
- SD 38 - , '"'.': .

~ 5~2~ :
stirring and cooling to result in a degree of sulfation of 0.8.
At this stage, a small portion of the mixture was removed, and, after removal of the nitrite groups and neutralization, the product was dialyzed~ isolated, and analyzed. The D,S was found to be 0.8.' The main portion was mixed with the stoichiometric amount of methanol required Eor the quantitative removal of the nitrite groups, and subsequently another portion of D~-S03 complex, which theoretically '' was sufficient to increase the D.S. to 2.0, was added over a period of ' 2 hours. After a total reaction period of 3 hours, the mixture was neutralized and the product isolated as described above, dialyzed, and its D.S. determined. The D.S. calculated was 0.8 indicating that no further substitution had occurred after removal of the'nitrite groups.
Similar results were obtained with guar and locust bean gums. ~ ' '~his illustrates that sulfation under'these conditions does not occur without the prior nitrosation step of an aspect of this invention as now '` ~' provided by the present Supplementary Disclosure.
EXAMPLE VIII
To test the compatibili~y of the various sodium ceIlulose .
sulfate esters of an aspect of this invention as now provided by the present Supplementary Discldsure with metal ions, 1% aqueous solutions -~
of the estçrs were mixed with the same volume of a 20% salt solutipn.
, ~ In cases where 20% was above saturation, a saturated salt solution was ,~ ~
,. . . .
uæed.
` Products at all D.S. levels were compatible, i.e., no precipi- `' tation or gelling occurred, with ammonium sulfate, sodium chloride, , potaseiuD`chloride,~magnesium chloride, calcium chloride, calciùm hydrox- ' ide, strontium chloride, strontium hydroxide, aluminum sulfate, sodium ~ '' aluninate, zinc sulfate, sodium ~incate, nickelous sulfate, cohaltous ~` ;
sulfate, cupric sulfate, cadmium chloride, ferrous sulfate, chromic ' ~-~chloride, lead acetate, mercuric acetate, silver nitrate, stannous chloride, and sodium stannite. ~ i' ; As a simple test for'determining compatibility with metal ions, ;

- SD 39 _ 6 ::

a 2% solution of the cellulose sulfate in an aqueous medium may be admixed with a 2% potassium chloride solution on an equal volu~e basis after heating of both solutions to a temperature of 80C. After mixing, the mixture may be allowed to cool. The compatability of the cellulose sulfate with potassium ions is shown by the absence of a precipitate and the absence of gelation.
Sodium cellulose sulfate esters with a D.S. of 1.3 and lower were compatible also with barium acetate, barium hydroxide, cerous chloride, and ~erric chloride. .
In mos~ cases, the solutions could be saturated with the salt without causing precipitation or gelation.
Among the other utilities for the cellulose sulfate products are their application in oil well drilling mud as a suspending agent, -in secondary oil recovery through water flooding as a thickener of the water phase, in cosmetics as an emulsifier and emollient, in food pro-ductæ as a thickener and stabilizer, in cleaning compositions as a ~ -. .:. . -:
stabili~er and thickener, in wax emulsions, paints, and photographic `
emulsions, e.g., for protein reactivity, etc. ``
EXAMPLE IX ~
Utilizing the process of the invention as now provided by an `
aspect of the present Supplementary Disclosure as described above, esters of polyhydroxy polymers such as, for example, polysaccharides, - : :
polyvinyl alcohols, and partially substituted etherified or esterified polysaccharides and polyvinyl alcohols which still contain a substantial .
number of free hydroxyl groups are prepared and the following specific ` ~

;products are obtained thereby. ;
; , . .
A. Nitrite esters of polysaccharides~ polyvinyl alcohols, polysaccharides partially substituted with stable rad-lcals, and polyvinyl ~ ; ~.' ~i ' ' ~ alcohols partially substituted with stable radicals.
B. Nitrite esters of starch, guar gum, locust bean gum, he~
,; ' 1 ' cellulose, gum arabic, mannan, alginic acid and pectic acid having a D.S. between 0.1 and the maximum.
!.: .. ..
~, , ;' , ' ' , . :

1~09LSlZ6 C. Nitrite ester of cellulose having a D.S. between 0.1 and 2Ø
D. Nitrite ester of cellulose having a D.S. between 2.0 and 3Ø
E. Water soluble nitrate esters of polysaccharides and poly-vinyl alcohols having a D.S. of less than 1Ø
F. Sulfuric acid esters of polysaccharides and polyvinyl alcohols and salts thereof with a D.S. of below 2.0 and with substan-tially uniform distribution of sulfate groups over the macromolecule.
G. Sulfuric acid esters of guar gum and locust bean gum having a D.S. of between 1.0 and 2Ø ;
H. Sulfuric acid esters of cellulose having a D.S. of between 1.0 and 2Ø xi I. Water soluble sulfuric acid esters of cellulose having a D.S. between 0.3 and 1Ø
J. Sulfuric acid esters of cellulose having a D.S. between 1.0 and 1.3,the aqueous solutions of which are compatible and non-gellable ;
in the presence of potassium, barium, strontium, cerous, aluminum, and ferric ions.
K. Sulfuric acld esters of cellulose having a D.S. of less than 2.0 and with substantially uniform distribution of sulfate groups over -the macromolecule, the aqueous solutions of which are compatible and non-gellable in the presence of potassium, strontium, and aluminum ions.
~XAMPLV X
Cotton linter pulp was dried at lO0 to 110C. in vacuo over :
P205 for 5 hours; a dried 20 g. portion was placed in a three-neck ~round bottom flask providPd with a calcium chloride tube, a strong stirrer, and a dropping funnel, and 1 liter of DMF was added. An amount of 30 g. of N204~ then was introduced with stirring over a period of 30 minutes while the temperature of the mixture was kept below 30C. by ;
;~oollng in a cold water bath. ~The mixture thickened, but the reaction ~ was incomplete even after mixing;for several hours indicated by the preeence of haze and apparently unreacted fibers. The addition of another 3 g. of N204 did not result in a substantial improvement.

SD 41 ~
.:
' ' .: .

~ ~5~
In isolating and analyzing the resulting cellulose nitrite ester, to a small portion of the mixture was added an excess of pyridine.
The slightly alkaline mixture was added to ice water, the precipitate collected, washed wlth ice water, and pressed out while the temperature r was kept at 0C. The material was redispersed in distilled water in a closed ~rlenmeyer flask and acidified with sulfuric acid. After stirring magnetically for 1 hour, the mixture was neutralized and the regenerated . . ~
cellulose removed, washed, dried, and weighed. The filtrate was collected quantitatively and the nitrite determined by oxidation with j -v ! -10permanganate to nitric acid. The presence of nitric acid subsequent to oxidation was established by its determination as nitron nitrate accor-ding to the method of Hick described in Analyst, Vol. 59, page 18 - 25 (1934). The degree of nitrosation was found to be 2.7-2.8.
The cellulose nitrite reaction mixture prepared from 20 g. of cellulose and 30 g. N204 was sulfated by the slo~ addition (30 min.) of a solution of DMF-S03 complex (6 g. S03) in DMF. The reaction was carried out with strong stirring and under exclusion of moisture, and the temperature was kept below 20C. The mixture remained hazy and still contained fibers even after mixing for 1 - 2 hours. The reaction 20mixture W8S then transferred to a mixer, diluted with 500 ml. of water, and adJusted to a pH of 7 - 8 by the slow addition of sodium carbonate solution. During neutralization, the temperature of the mixture was kept below 20 - 25C. by the addition of ice. Enough isopropanol was then added to separate the product, and the product was pressed out, washed twice with aqueous isopropanol, pressed out again, dried in vacuo at 100C., and milled. The product had a D.S. of 0.6 and a 1~ aqueous solution a viscosity of 3000 cps. ~Brookfield Viscometer, LVT Model, 60 RPM) but was somewhat hazy and contained fibers. ~
':', :..
In another experiment, 20 g. of anhydrous cotton linter pulp 30 was treated as described above, but only 15 g. of N204 was used for the ~nitrosation to result in a D.S. of 1.5 and an amount of DMF-S03 complex ~ ;containing 12 g. of S03 for the subsequent sulfation. The results were '.
'? f~ - SD 42 -~,. . .

~O~S1~6 similar to those above. The cellulose sulfate had a D.S. of 1.5, and a 1% aqueous solution had a viscosity of 500 cps. but was hazy and con-tained fibers.
Essentially similar results were obtained when wood céllulose, cellulose from vegetable hulls or bagasse, and chemically treated and degraded cellulose, such as, for example, Whatman Cellulose Powder were <
substituted for the cotton linter pulp. ~owever, it appeared that the reaction with Whatman Cellulose Powder proceeded more smaothly and that a solution of its final sulfated product was the least hazy and contained 10a lesser amount of fibers than-those produced from other cellulose types.
Substitution of the D~ in the reaction medium by DMAC or pyridine or mixtures of these compounds did not essentially change these results. Also, no essential differences were noticed when the SO3 was used as a complex with other solYents, such as9 for example, DMAC, dioxane, DMSO, and the like, or when NOCl was used instead of N2O4 pro-vided, however, that the molar amount of NOCl was increased 2.5 to 3 .: . .
fold.

EXAMPLE XI -Cotton linter pulp as described in Example X was suspended in ;20 water and mixed in a Waring Blender for 2 min., pressed out, washed with ~

DMF, and pressed out again. The cellulose then had a water content of `

8 - 10%. A portion of 20 g. of this cellulose then was nitrosated with ;

30 g. of N2O4 as described above. The resulting solution was clear and : . :
did not contain fiberæ after a reaction time-of 20 ~ 30 min., and no excess of N2O4 was required to obtain a quantitative reaction. The sul-fatlon was carried out as described above and resulted in products ~forming perfectly clear solutions~that did not contain fibers.
Similar results were obtained when the residual water content was 5% and 2% or when cotton cellulose was rPplaced by wood cellulose or ;~ 30 cellulose from bagasse or chemically treated cellulose.

When the amount of DMF-SO3 complex added was that calculated to ~ -.
produce a D.S. of below 0.3-0.4, the resulting product was inæoluble but ;, ~ . .
': ' ' '`' ,' ' ' ' ,~ ~ - SD 43 -~=,.
.:

~ 5~6 highly swellable in water.
EXAMPLE XII - -Cotton linter pulp was hydrated by treatment with water in a Waring Blender as described above. The cellulose then was pressed out and divided into four portions. One portion was dried in vacuo at 30 -40C. with continuous mixing down to a water content of 20%. The other three parts were dried under the same conditions to 8 - 10%, 4 - 5%, and 1 - 2% water, respectively. For the last sample the te~perature was somewhat increased. Amounts of 20 g. of each of the parts were nitro-sated as described above with 30 g. of N204. The reartions with samples containing 8 10% and 4 - 5% moisture proceeded smoothly and were com-plete after 20 - 30 minutes forming clear, viscous solutions. The cellu-lose containing 20% moisture required 35 ~. N204 ànd formed a clear solu-tion soon after the 5 g. excess had been added. The cellulose portion ~-;
containing 1 - 2% moisture required a long time of mixing and, even after `~
the addition of a moderate excess, remained somewhat hazy and contained -~
fibers.
: .:: . .
Subsequent sulfations using DMF-S03 co~plex containing 6 g. of S03 in each case resulted in cellulose sulfates with a D.S. of 0.6 pro-ducing sparkling clear solutions in water when celluloses with moisture .
contents of 20%, 8 - 10%, and 4 - 5% were used initially. Solutions of the reaction product from ceilulose with the lowest moisture content, however, were somewhat hazy and appeared to contain fibers. :
Similar results were obtained when cotton linter pulp was -replaced by wood cellulose or cellulose from vegetable hulls or bagasse, or when the;DMF was substituted by DMAC, or when instead of the DMF-S03 complex, a complex with dioxane, DMAC, DMSO, or the like was used.
In another ide=tical experimental series, where 20 g. portions ~of cellulose were nitrosated with 20 g. of N204 (25 g. of N20~ required ~ ~or the cellulose containing 2QX moisture) and sulfated with DMF-S03 complex containing 10 - 12 g. of S03, products with D.S. values of 1.1-1.2 were obtained, but otherwise resul~s were similar.

.;

The nitrosation and subsequenl sulfation proceeded slmilarly smooth and resulted in sulfated products forming clear aqueous solutions when a commercial eotton linter pulp or wood cellulose with moistlire contents of between 4 - 12% was used directly. If 5%, 10%, or 20% water was added to anhydrous cellulose at once just before the reaction, results were similar to those obtained under Example X with anhydrous cellu~ose.
EXAMP~E XIII
Five samples of cotton linter pulp (20 g. each) were nitrosated as described above with 30 g. of N204 each and then sulfated with DMF-S03 complex containing the theoretical amounts of S03 calculated for D.S.
values of 0.4, 0.6, 0.8, l.l, and 1.6. After neutralization and isola-tion, the D.S. values of the products were found to be 0.4, 0.6, 0.8, 1.1, and 1.1, respectively. The same D.S. values of 1.0-1.1 were ; `
obtained also when the amount of N204 was reduced to 25 g. or 20 g. and ;~
the S03 was calculated for a D.S. of 1.1 and 1.6.
- Cotton linter pulp (20 g.) which was nitrosated with 14 to 15 : ,~; . .
g. of N204 produced, after sulfation with a theoretical amount or a moderate excess of S03, a product with a D.S. of 1.5 to 1.6. If the N204 was increased to 17 to 18 g., a theoretical amount or an excess of S03 produced a D.S. of 1.3 to 1.4. However, if for the nitrosation 25 g.
of N204 was used, theoretical amounts of S03 were sufficient to produce ~ -D.S. values of between 0.5 and 1.1. If less than 10 g. of N204 was used for nitrosation~ no complete sulfation was attained with DMF-S03 romplex even when used in moderàte excess. Substantially simllar results were obtained when, instead of cotton linter pulp, wood cellulose or bagasse was used.
EA~ E XIV
Carboxymethyl cellulose (lO g.) with a D.S. of 1.0 was sus-pended in 500 ml. DMF, and 7.5 to 8.0 g. N204 was introduced under exclusion of moisture and with strong agitation. The mixture formed a . :,. :
light green, viscous solution of carboxymethyl cellulose dinitrite ester.

- SD 45 - `
:

~045~Z~
For the isolation and identification of the ester, the sa~e p~ocedure was used as described under Example 1 in the Principal Dis-closure for cellulose nitrite ester. If less N204 was used for the nitrosation, the degree of nitrosation was correspondingly lower.
Similar results were obtained when methyl cellulose with a D.S. of 1.0 and 1.5, hydroxypropyl cellulose with a D~S. of 0.8, acetyl alginic acid esters with a D.S. of 0.5 and 0.8, hydroxyethyl starch with a D.S. of 0.2, partially hydrolysed polyvinyl acetate with a D.S.
of 0.4, acetyl pectic acid ester with a D.S. of 1.2, hydroxyethyl guar and locust bean gums with a D.S. of 0.4 and 0.7, hemicellulose nitrate ester with a D.S. of 0.4 and 0.7, hemicellulose nitrate ester with a D.S. of 0.3 (as described in the German Offenlegungsschrift No.
2,120,964), polyvinyl alcohol sulfuric acid ester with a D.S. of 0.3, starch phosphate, carrageenan (free acid), xanthan gum (free acid), or gum karaya were nitrosated under similar conditions with stoichiometric amounts of N204 to result in complete or partial esterification of the free hydroxyl groups.
Similar resulted were obtained whe~ the DMF was replaced by ~DMAC, pyridine, isoquinoline~ quinoline, and the like, or when NOCl ;
instead of N204 was used provided that its molar amount was essentially tripled. Also~ the reaction medium could contain substantial quantities of an inert solvent, such as, for example, ethyl acetate, ethyl formate, , . . ,:
benzene, toluene, ethylene dichlorlde, acetone, methyl ethyl ketone, and the like, without subst~ntially changing the reaction.
EXAMPLE XV

~ : -, .:
~ DMF (100 ml) was poured into a 250 ml two-neck round bottom :
flask equipped with calcium chloride tube and magnetic stirrer. Then, 23 g. of N204 (1/4 mole) was added with stirring and cooling which resulted in the formation of a deep green solution. To this solution, 12 g. absolute ethyl alcohol (1j4 mole) was added slowly with stirring.
Durlng addition of the last ml, the solution became light yello~ indica~
ting complete consumption of the N204. Then, the solution was ~;
. .
, -5~Z6 neutraliæed by the addition of pyridine and sub~ected to fractionated distillation. The first fraction was collected in a flask cooled with acetone - dry ice and consisted of 18 g. of a yellowish liquid having a boiling point of 17 - 18C~ No ethyl alcohol was recovered during distillation. .-Using the same conditions as in Example XV, the ethyl alcohol -was replaced by propanol, isopropanol, butanol, isobutanol, tertiary butyl alcohol, amyl alcohol, isoamyl alcohol, and hexyl alcohol and 1/8 mole ethylene glycol. On fractionated distillation, the corresponding nitrite esters were recovered in 80 - 90% yields with boiling points of t ~: :
57C., 45C., 77C., 68C., 63C., 104C., 99C., 130C., and 98C., respectively. In no case was any alcohol recovered.
In another series of experiments, 15 g. of a low D.P. cellu-lose was suspended in the 100 ml. of DMF before the N204 was added. `~
Addition of 23 g. of N204 with strong stirring resulted in a cellulose trinltrite ester solution. To this solution, alcohol under conditions and in amounts as described above (1 mole alcohol or 0.5 mole diol per -~
mole N204) was added. Free cellulose separated and was removed. The filtrate was neutralized and distilled as described above and the corres-ponding alkyl nitrites were obtained in yields of 80 - 85~ of the theory.
: -Similar results were obtained when, instead of cellulose, stoichiometric . . .: .
amounts of methyI cellulose, starch, alginic acid, or polyvinyl alcohol were used. ;
In a third experimental series. to cellulose trinitrite ester solutions obtained under conditions and in amounts as described above were added slowly and wlth cantinuous stirring amounts of DMF-S03 com-pIex to result in mixed cellulose nitrite sulfuric acid esters having degrees of sulfation of 0.4;, 0.8, and 1.1. To thse ester solutions, alcohol was~added under conditions and in amounts as described above, the ;
30 cellulose sulfuric acid ester precipitated by the addition of a suffi-~ : : ; , cient amount of acetone and removed, and the filtrate neutrali~ed with ,:
~ pyridine and subjected to fractionated distillation. The corresponding :: :
... . ...
:: `:, ' :
., :'''.~, '' 1~5126 alkyl nitrites were recovered in a purity and in yields similar to thoseobtained from cellulose trinitrite ester solutions above.
EXAMPLE XVI
Cotton linter pulp (400 g.) having a moisture content of 5 - 6%
was mixed with 2 1. of DMP in a doub:Le planetary mixer with cooling and :.
under exclusion of moisture, and 600 g. of N2O4 was added over a period of 30 minutes to result in a cellulose trinitrite ester. Then, a DMF-SO3 slurry in DMF containing 200 g. of S03 was added slowly over z period of ~
30 minutes and mixing continued for another 10-15 minutes. An amount of ~ :
485 g. of isobutyl alcohol was added slowly, and the miY~ture was neutralized (pH 7-8~ by the addltion of an aqueous solution of sodium carbonate or a slurry of sodium carbonate in a saturated solution or by the addition of dry sodium carbonate. Good and thorough mixing was ` ~
required for thi~ neutralization step, and generally the presence of `
water produced better results. The temperature of the reaction mixture -~
was maintained below 20C. throughout the reaction until neutralization was complete, and up to the neutralization step, the reaction was carried ;
, ~ , . . .
out under exclusion of moisture. The neutral mixture was then pressed `~
out or centrifuged, and if the solids were too soft to be pressed out, ~0- some isopropanol was added to harden them sufficiently. The solids were ~ `
~suspended in 60 - 70% aqueous isopropanol, pressed out again, dried, and milled. For higher purity, the solids were suspended in aqueous j ;-isopropanol a second and, if necessary, a third time before final drying and milling.
~ The filtrates were comhined and sub~ected to fractionated dis-tillation for sol~ent recovery. One of the fractions distilled at 66-67~C.

.
and was identified as isobutyl nitrlte, the yield being over 80%. The . .
brown,~crystalline residue from distillation contained the theoretical amount of sodium nitrite. An aliquot of it was purified by recrystalli-zation.

, ~ In other identical experimentsl the isobutyl alcohol was .::: :.
replaced by n-propanol, amyl alcohol, and ethylene glycol. Ins~ead of ';~ ~ , ,';

~' '' .,~ ';:' ..... .. . ..

; : , :, , . ~,, : ,, : .. , , . ., .". , , . ~ , lO~ Z6 isobutyl nitrite, the corresponding nitrite esters of n-propanol, amyl alcohol, or ethylene glycol were ~ecovered, but otherwise results were similar. In another similar experiment where the isobutanol was replaced by an equivalent amount of water, similar results were -obtained, but the residue from the solvent recovery contained equivalent amounts of sodium nitrite and sodium nitrate in theoretical yields. Part of the residue was recrystallized to result in a purified salt mixture. -The sodium cellulose sulfate had a D.S. of 1.0-1.1, and a 1%
aqueous solution had a viscosity of 1500-2000 cps.
In another experimental series, products were obtained under similar conditions, but the amount of SO3 used for the sulfation was -reduced to obtain products with D.S. values of 0.4, 0.6, and 0.9. These - -D.S. values were attained with the theoretically calculated amounts of S03, and 1% aqueous solutions of the products had viscosities ranging between 5000 and 2000 cps. In another experiment, the amount of N2O4 was reduced to 300 g. and that of S03 increased to 300 g. to result in sodium cellulose sulfate esters with a D.S. of 1.5-1.6 having 1% aqueous ~ -viscosities of 600-700 cps. `~
Other cellulose materials, such as, for example, wood cellulose or cellulose from vegetable hulls were used with equal success, but the .:: .:. ~
final products had a somewhat lower solution viscosity than those from ~ ~ ~
.
high D.P. cotton linter pulp. Also, neutrali~ation could be carried out equally well with carbonates, bicarbonates, and hydroxides of the other `
:
alkali metals, such as, for example, lithium and potassium, of alkali earth metals, such as, for example, magnesium and calcium, and of manganese, cobalt, and nickel and with ammonium hydro~ide and amines. ;
In the case of the alkall metals, carbonates and bicarbonates are pre-ferred to the hydroxides because of the high alkalinity of the hydroxides and~the danger of degradation. ; ;

Also an integral part of this invention as now provided by an aspect of the present Supplementary Disclosure is the process of making ; ~ O films, fibers, snd other shaped srticles by (1) preapring a solution or ,`, ?~ ; .:
~ - SD 49 -,' . '' , 51 Z6 ~ ~ m ~ , paste contai ing the labile nitrite ester of one or more plyhydroxy~ * O
polymers or a solution or paste of both one or more polyhydroxypolymer ~ p ~ ~
nitrite esters and one or more polymers lacking hydroxyl groups and (2) --;
contacting the solution or paste with a protic solvent in the presence of an acidic catalyst to cause (a) regeneratlon of the polyhydroxypoly-mer and, essentially simultaneously, (b) separation of both the regenerated polyhydroxypolymers and the polymers lacking hydroxyl groups in such a manner that films, fibers, or other shaped articles are obtained.
10The first step of the process consists`of making the nitrite :: :
ester of the polyhydroxypolymer or polyhydroxypolymer mixtures as pre- -;
viously described. As the polyhydroxy compound, any polymer containing a substantial number of hydroxyl groups is suitable. This includes poly-saccharides typified by cellulose irrespective of its source, alginic `-acid, pectic acid, pectin, hemicellulose, gum arabic, guar gum, locust bean gum, gum karaya, and the like, polysacchariide derivatiues still con-taining ~ substantial number of hydroxyl groups as typified by carageenan ~and other polysaccharide sulfates, methylcellulose, carboxyalkylcellulose, hydroxyalkylcellulose, hydroxyalkylguar and other polysaccharide ethers, 20 ipartially acetylated or generally esterified polysaccharides, partially ;,~
nitrated or sulfated polysaccharides such as, for example, described previously, and the like, and synthetic polyhydroxypolymers typified by ; polyvinyl alcohols with various degrees of saponification and copolymers containing vinyl alcohol.
To the suspension of the polyhydroxy polymer(s) in one of the .
specified solvents or solvent mixtures, enough dinitrogentetroxide and/or nitrosylchloride is added in gaseous or liquid form or as a solution pre-ferably in one oE the previously mentioned solvents to obtain a highly i;
esterified~nitrite ester of the polyhydroxy polymer(s). The reaction temperature should be maintained below 50C. and preferably below 30C.

If the temperature increases to above 60C. over an extended period of ;
time, some nitration of the polyhydroxy polymer may occur. This, however, .... .
- SD,50 , ~
.~:

-S~Z6 may not have any disadvantageous consequences ln the subsequent film or fiber formation and, in some instances, it may be even desirable. -~
Films, fibers, and other shaped articles of the unmodified polyhydroxy polymer(s) are obtained by bringing the paste or solution of the nitrite ester(s) into the desired shape and then contacting it in the presence of an acidic catalyst with a protic solvent in which the resulting polyhydroxy polymer(s) is (are) insoluble. Films9 for example, can be made by spreading the solution on a glass plate and treating it with a protic solvent while fibers are obtainable by extruding the solu- -tion into the protic solvent. The shaped objects then may be immersed in and washed with more solvent and dried. To neu~ralize residual catalyst9 a small amount of a base, such as, for example, alkali or ammonium hydroxides or an amine, may be added to one of the washes if so desired.
Although it is possible first to isolate the polymeric nitrite ester and then redissolve it for the purpose of film and fiber formation, it is preferred to uæe the reaction solution containing the nitrite ester directly. The preferred acIdic catalyst is a mineral acid, such -as, for example, hydrochloric, sulfuric, nitric, phosphoric acids, and the like; however, relatively strong organic acids are suitable also. ~
If an N,N-dialkylacylamide had been used as the proton acceptor for ;
.: :,::, - .:
nitrosation of the polyhydroxy pol~i~er, the nitric acid and/or hydro-chloric acid formed simultaneously as a by-product is sufficient to ,.:, ~ s~erve as a catalyst. Howevers if a weak tertiary amine had been used -~;
. . .
for this purpose, enough catalyst should be added to make the mixture ~acidic. The catalyst must be anhydrous to avoid removal of nitrite .: : , , ; groups prior to the treatment with the protic solvent. Of course~ a sufficient amount of catalyst may be added to the pro~ic solvent instead -~
of to the nitrite ester solution, and film or fiber formation is achieved ~5 30 with similar success. In the case of a nitrite ester solution where a ~. ,, ~ .
N,N-dialkylacylamide~is used~as~the proton acceptor, it may be advan-tageous to neu~ralize or slightly alkalize the solution to eliminate the : ::, :, :
:~ : ,.

..:: .:
. ` , . ,:

~045~6 reactivity to moisture and add the catalyst to the protic solvent. The protic solvent to be used depends largely on the polyhydroxy polymer to be regenerated. For most polysaccharides and synthetic polyhydroxy polymers, anhydrous or aqueous alcohols, such as,for example, methanol, ethanol, isopropanol, and the like, are required because of the water solubility of these polymers. In the case of cellulose or a mixture of a substantial amount of cellulose and another polyhydroxy polymer, water may be used as well. At times, it is advantageous, i.e., the polymer separation is improved, if the protic solvent is mixed with another type of solvent provided that this second solvent does not inactivate the catalyst and that it is completely miscible with the protic solvent as well as with the nitrite ester solvent.
In addition to the polyhydroxy polymer nitrite esters, other soluble polymers may be added to the nitrite ester solution. Tbsis may be done by dissolving the polymer directly in the reaction mixture con-talning the nitrite ester or by pre-dissolving the polymer in a suitable -solvene and adding the resulting solution to the nitrite ester solution or vice versa. Although, because of simplified solvent recovery, it is preferred to use the same solvent as contained in the nitrite ester reactlon mixture, other aprotic solvents, such as, for example, chlori-nated hydrocarbons, hydrocarbons, alkyl esters, aromatics, acetonitrile, dioxane, and the like, may be used for pre-dissolving the polymer pro- i ~
vided that such solvent is compatible, i.e., completely miscible, with l~ -the nitrite ester reaction solution and with the protic solvent to be contacted with subsequently. Of course, if the nitrite ester solution ~
is~neutral or alkaline, l.e.j does not contain the acidic catalyst, such -solvent may also be protic as typified by alcohol and water. In this case, the acidic catalyst is added to the protic solvent to be used -~' . .
subsèquently for the regeneration of the polyhydroxy polymer and the separ=tion of the polymer mixture in the form of certain shaped articles.

The type of additional polymer which may be added to the nitrite ester solution may be any polymeric compound which either does not contain any -, ,~ .

hydroxyl groups or the hydroxyl groups of which are essentially completely substituted. Pol~ers of that type are synthetic polymers typified by polyacrylic esters, methacrylic esters, polyacrylonitrile, and other acrylics, polyvinylesters, -ethers, and-halides, vinly and acrylic copolymers, polystyrene and copolymers, ethylene copolymers, propylene copolymers, phenolics, polyamides such as, for example, nylon, polyethers, polyesters, polyalkylene glycols, and others and highly substituted polysaccharides typi~ied by their nitrate, acetate, propionate, and other esters, their methyl, ethyl, and other ethers, and the like. The only requirements are that such po]ymer is soluble in one or more of the above solvents, that it is compatible with the polymeric nitrite ester solution, and that it can be separated simultaneously with the polyhydroxy polymer by the proper choice of the protic solvent or the solvent mix-ture containing the protic solvent. A limited amount of an additive, such as, for example, a plasticizer, or of a liquid lower molecular weight polymer may be added also provided, of course, that it is retained . :, .
in the film or fiber and not leached out during film or fiber formation.
Films, fibers, and other shaped objects are obtained by contact with a ~-protic solvent in the presence of an acidic catalyst in ~he way described above. As already mentioned, the choice of the protic solvent depends on the polymer mixture, and it should be selected in such a way that, on contact, regeneration of the polyhydroxy polymer and separation of both the polyhydroxy polymer and the polymer lacking hydroxyl groups ;
occur essentially simultaneously. Of course, prior to contact with a ~5 protic solvent, part or most of the polymer solvent, especially in ~he case of a low boiling solvent, may be evaporated and, thusg the polymer .
concentration increased. This often improves fiber and film formation. ~
, ....
The shaped articles obtainable by the process as no~ provided by an aspect of the present Supplementary Disclosure consist of homo- -geneous and intimate mixtures of the polymers originally present in the .. . ..
polymeric nitrite ester so~ution. Thus, they may consist of only one polyhydroxy polymer, or they may consist of a combination of several . .

1t)~5~2~ii polyhydroxy polymers or of one or more polyhydroxy polymers and one or more polymers lacking hydroxyl groups. Of course, lf desired, unreacted cellulose fibers may be included in such articles by suspending the desired amount of cellulose fiber in the polymer solution prior to film or fiber formation. In combination of several polymers, the polymer ratio can be chosen arbitrarily, and the weight percentage of any poly-mer may vary between 0.1 and 99.9.
Shaped articles containing acidic polymers, such as, for example, polymeric sulfuric or phosphoric acid esters, polyuronic acids, polyacrylic acid, and the like, may be modified further by neutrali7ing with various bases, such as, for example, alkali, ammonium and alkali earth hydroxides and the various primary, secondary, and tertiary amines.
Also, the alkali salt of such acidic compound may be treated with a quaternary ammonium halide resulting in an exchange of the alkali ion by the quaternary ammonium ion. This will produce property changes of the shaped object, such as, for example, increased or reduced water sensiti-vity or even water repulsion depending on the ion selected.
The usefulness of the shaped articles, particularly films and ~`
fibers, is obvious and need not be demonstrated. Films of cellulose, cellulose acetate, and cellulose nitrate, for example, are used ln packaging material, membranes, and the like, films of other polysacchar-ides are used as food packaging materials, and fibers of cellulose, polyesters, polyamides, and other polymers are used in the manufacture of, for example, textiles. The novel combination of several polymers as described in thls invention as now provided by an aspect of the present Supplementary Disclosure, suoh as, for example, cellulose - polyester, celluIose - polyvinyl alcohol, polyvinhl alcohol - nylon, and the like, '': ':
in the same film or fiber wlll combine some of the advantages of the individual poly~ers but also will add new properties, such as, for example, possibly higher strength, increased flexibility, improved dyability, antistatic properties, and the like. The incorporation of a : :
negatively charged polymer in, for example, cellulose or cellulose ~
' .

~ ~ - SD 54 -. ~

~s~z~ ;:
acetate films may be useful in their application as osmotic membranes or, because of the added protein reactivity, in the meat industry as, for example, sausage casing and in medical applications.
The following examples illustrate specific preferred embodi-ments of this invention as now provided by an aspect of the present Supplementary Disclosure.
EXAMPLE XVXI
High molecular weight cotton linter pulp (10 g.) was suspended in 300 ml. DMF and, under exclusion of moisture, 16 g. dinitrogentetrox-ide was introduced slowly and with mechanical agitation. Strong agita-tion was continued until a clear highly viscous solution ~Jas obtained.
Part of the solution was spread evenly on a glass plate in a low humidity chamber and then sprayed with anhydrous or aqueous methanol, the film removed, blotted between filter paper, immersed in and washed with methanol, and dried. The film was clear and strong. Fibers of high clarity and strength were obtained by extrud mg the ~olution through fine nozzles into methanol, washing the resulting fibers with fresh methanol, and drying. If droplets of the solution were dropped into -~
methanol, washed with methanol, and dried, the product was obtained in the form of granules. The granular size depended on the concentration of the cellulose in tl;e solutlon and on the size of the droplets. ~:
: . , .
~ Similar results were obtained wllen a lower molecular weight : - ,. , cellulose or cellulose from other sources was used or when th~ cellulose : . ":
~ ~ ;was replaced by polyvinyl alcohol, starch, hemicellulose, guar gum, ;,: . , ~, . . :
locust bean gum, alginic acid, pectic acid, hydroxyethyl cellulose, methyl cellulose with a D.S. of 1.5, or propylene glycol alginate. ;

EXAMPLE XVIII
; .

Cotton linter pulp (5 g.) and 5 g. polyvinyl alcohol were ~ , :
suspended in 200 ml. DMF, and sufficient dinitrogentetroxide was intro-,, . ~ . .
duced to result in a clear viscous solution on prolonged mixing. Films, ~;

fibers, and granules~were obtained from this solution as described under : . : , Example XVII. Substitution of nitrosylchloride for dinitrogentetroxide : ' ':

~O~S~26 or of a mixture of DMF and benzene for DMF produced similar results.
The same results were obtained when the ratio of the two polymers was changed to 8:2 or 2:8 and/or when other polymer mixtures were used, such as, for example, cellulose - starch, cellulose - cellu-lose sulfuric acid ester, cellulose - carrageenan, cellulose - alginic acid, cellulose - pectic acid, cellulose - guar gum, cellulose - gum arabic, starch - alginic acid, starch - pectic acid, and when mixtures of three or more of the above polymers were used.
If the methanol used for separating films and fibers was replaced by ethanol, isopropanol, aqueous acetone, and methanol - acetone mixtures, films, fibers, and granules of the polymers were obtained equally well. ``-Films, fibers, and grar.ules containing an acidic polyhydroxy - polymer were neutralized by immersing in aqueous or anhydrous methanol ~ -containing ammonium, sodium, or potassium hydroxides, propylamine, ~ ~-dibutylamine, trilaurylamine, or triethanolamine. Softness, flexibility, water sensitivity, and other characteristcs of the products depended to ~-some extent on the base used for neutralization.
EXAMPLE XIX `~
Cellulose (10 g.) was suspended in 2~0 ml. DMF and 15 g.
dinitrogentetroxide introduced to obtain a clear solution. A solution ~ - .: , .
~ of lO g. of polyvinyl acetate in 50 ml. ethylacetate was added, and from , .
this mixture, films and fibers were prepared in a manner described under . . , Example XVII. ~ilms and fibers were obtainable équally- well when starch, alginic acid, guar gum, or hydroxypropyl cellulose was substituted for cellulose andtor celluIose nitrate, cellulose acetate, polyacrylic ester, -:
or polymethacrylic ester substituted for polyvinyl acetate.
In another experiment, the polyvinyl acetate solu~ion was replaced by a solution of~lO g. of nylon in hot DMF and9 in a further, 30 ~ experiment,~by 10 g. polyethylene g~lycol in DMF, and films and fibers were prepared ~ith equal success.
Changing the ratios of the polymers in the solutions did not - : `
~ - SD 56 ~
i ';, :~45~Z~
adversely affect film and fiber formation.
EXAMPLE X~
Polyvinyl alcohol (10 g.) was suspended in 80 ml. DMAC, 10 g.
dinitrogentetroxide introduced with mechanical stirring and under exclu-sion of moisture, and stirring continued until a clear solution was obtained. Then, a solution of 10 g. polyacrylonitrile in 50 ml. DMAC
was added and the resulting clear solution of the polymer mixture used for film and fiber formation. A mixture of benzene - isopropanol - water was used for separation of the polymers, and isopropanol was used for ~ ~
10 washing. -Essentially similar results were obtained when the polyacry-lonitrile solution was replaced by solutions of methyl vinyl ether -maleic anhydride copolymer, polyester, polyvinyl chloride, polyketone, ,~
phenolic resin, ethylene - acrylic acid copolymer, or polystyrene, or by a solution of two of such polymers and/or polyvinyl alcohol was sub-stituted by guar gum or a mixture of cellulose and starch. -: , :: .
EXAMPLE XXI -~
~ydroxyethyl cellulose (10 g.) was solubilized in a mixture of 85 ml. DMF and 15 ml. pyridine by introducing a sufficient amount of -~
20 dinitrogentetroxide and the resul~lng solution mixed with a solution of ~ ~-polyvinyl hydrogenphthalate (10 g.) in DMAC. The resulting solution of the two polymers then was spread on glass plates and the plates immersed -~
in aqueous ethanol containing hydrochloric acid in excess to the amount ^~
of pyridine on a molar ~asis. The films then were removed, washed with ethanol, kept in ethanol containing a small amount of ammonia, and dried.
EXAMPLE XXII
: -,: . . .:
Cellulose (10 g.) was solubilized in a mixture of 50 ml. DMF
and 50 ml. ethyl acetate with a sufficient amount of dinitrogentetroxide, ; -and a solution of 12 g. cellulose acetate in 100 ml. ethyl acetate was - `
30 added. The resulting solution was spread on glass plates in a low humidity chamber, most of the solvent removed by evaporation under reduced pressure, and the plates immersed in methanol. The films were washed with ' .
.:

~5~Z~
methanol and dried.
Similar results were obtained when polyvinyl acetate was sub- ;
stituted for cellulose acetate and/or alginic acid for cellulose. I -'.

' ; .
. .
. . .

'~

: ;
. .
; -: .
,~ . . ,.,, -.

`' ', ~, 'f!
: , .

Claims (43)

The embodiments of the invention in which an exclusive prop-erty or privilege is claimed are defined as follows:

1. A process which comprises, as a first step, reacting a poly-hydroxypolymer in a suitable solvent including a proton acceptor and a swelling or solubilizing agent with a compound selected from the group consisting of dinitrogentetroxide, nitrosykc and mixtures thereof at a temperature below 50°C. under essentially anhydrous conditions;
and, as a second step, one of the following additional steps:
(a) heating the corresponding polymer nitrite ester solution in the presence of (i) nitric acid, or (ii) nitric acid and an acid anhydride;
(b) sulfating the corresponding polymer nitrite ester with sulfur trioxide or with a complex thereof, and reacting the mixed polymer nitrite sulfuric acid ester reaction mixture so obtained with a protic solvent, thereby to remove residual nitrite groups; or (c) sulfating the corresponding polymer nitrite ester with sulfur trioxide or with a complex thereof, and reacting the mixed polymer nitrite sulfuric acid ester reaction mixture so obtained with a protic solvent, thereby to remove residual nitrite groups, and finally neutralizing the polymer sulfuric acid ester so formed, to slightly alkaline with a base.

2. The process of claim 1 wherein the polyhydroxypolymer is a polysaccharide or a polysaccharide-derivative containing free hydroxyl groups. .

3. The process of claim 1 wherein the polyhydroxypolymer is a synthetic polymer containing free hydroxyl groups.

4. The process of claim 1 wherein the polyhydroxypolymer is selected from the group consisting of cellulose, starch, guar gum, locust bean gum, hemicellulose, alginic acid, pectic acid, gum arabic and polyvinyl alcohol.

5. The process of claim 1 wherein the solvent consists of one compound capable of functioning as both the proton acceptor and the swelling or solubilizing agent.

6. The process of claim 5 wherein the one compound is selected from the group consisting of N,N-dimethylformamide, N,N-dimethylaceta-mide, pyridine, quinoline and isoquinoline.

7. The process of claim 1 wherein the solvent consists of a mixture of a proton acceptor compound selected from the group named in claim 6 and another compound, which generally is capable of solvating or dissolving polymer esters, as the swelling or solubilizing agent.

8. The process of claim 7 wherein the swelling or solubilizing agent is selected from the group consisting of ethylacetate, ethylfor-mate, benzene, acetone and methyl ethyl ketone aetone.

9. The process of claim 1 wherein polymer nitrite esters with a degree of substitution of between 0.1 and the maximum are obtained.

10. The process of claim 1 for the preparation of a polymer nitrate ester which comprises heating the corresponding polymer nitrite ester solution in the presence of nitric acid or in the presence of nitric acid and an acid anhydride.

11. The process of claim 1 for the preparation of a polymeric sulfuric acid ester or a salt thereof which comprises the steps of:
(a) sulfating a polymer nitrite ester with sulfur trioxide or a complex thereof to obtain the mixed polymer nitrite sulfuric acid ester;
(b) reacting the mixed polymer nitrite sulfuric acid ester reaction mixture with a protic solvent to remove residual nitrite groups resulting in polymer sulfuric acid ester; and (c) neutralizing to slightly alkalinizing the polymer sulfuric acid ester with a base to obtain a salt of the polymer sulfuric acid ester.

12. An ester of a polyhydroxy polymer, said ester being selected from those esters:
(a) consisting essentially of a mixture of nitrite ester groups and nitrate ester groups;
(b) consisting essentially of a mixture of nitrite ester groups and sulfate ester groups;
(c) consisting essentially of nitrate ester groups with a degree of substitution of below 1 and derived by complete elimination of the ni-trite ester groups from (a) above; and (d) consisting essentially of sulfate ester groups with a degree of substitution of below 2 and derived by complete elimination of the ni-trite ester groups from (b) above.

13. The ester of claim 12 wherein the sum of the degree of sub-stitution of said nitrite groups with the degree of substitution of said nitrate ester groups or said sulfate ester groups is equal to the maximum degree of substitution of the polymer.

14. The ester of claim 12 comprising a polymeric sulfuric acid ester or a salt thereof formed from said ester (b) by the complete elimina-tion of nitrite ester groups, whereby all said ester groups are sulfate groups.

15. The ester of claim 14 wherein said polymer is cellulose, whereby said sulfuric acid groups are essentially uniformly distributed over the cellulose molecule.

16. The ester of claim 14 wherein said polymer is guar or locust bean gum, and wherein said sulfuric acid esters or salts thereof have a degree of substitution of above 1Ø

17. The ester of claim 14 wherein said polymer is gum arabic or hemicellulose.

18. The ester of claim 12 comprising a polymeric nitrate ester formed from said ester (a) by the complete elimination therefrom of nitrite ester groups, whereby all said ester groups are nitrate groups, wherein nitrate ester groups are substantially uniformly distributed among the polymer units of said polyhydroxy polymer.

19. The ester of claim 12 wherein said polyhydroxy is a polysaccharide or a polyvinyl alcohol.

20. The ester of claim 18 wherein said polyhydroxy polymer is a polysaccharide of polyvinyl alcohol.

21. The ester of claims 10 or 20 wherein said polyssaccharide is cellulose.

22. The ester of claim 18 comprising a thickened aqueous medium containing water and said water-soluble nitrate ester, with said water-souluble nitrate ester being present in an effective amount to -thicken said aqueous medium.

23. The ester of claim 22, wherein said polyhydroxy polymer is cellulose.

24. A water-soluble colloidal sulfate ester of cellulose having a degree of substitution of 0.3 to 1.0;
said sulfate ester having a substantially uniform distribution of sulfate ester groups among the polymer units of the cellulose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, al, Zn, Ni++, Co++, Cu++, Cd, Fe++, Cr+++, Pb, Hg++, Ag, Sn++,Ba, Fe+++, and Ce+++ ions.

25. The esters as claimed in claim 24 in the form of their metal salts.

26. The esters of claim 24 in the form of a thickened aqueous medium containing water and said water-soluble sulfate ester of cellulose, wherein said sulfate ester is present in an effective amount to thicken said aqueous medium.

- 62a -Claims Supported by the Supplementary Disclosure

27. A process as claimed in claim 1 for preparing a nitrate ester of a polyhydroxy polymer which is a polysaccharide or a polyvinyl alcohol that is partially substituted with at least one of ether and ester groups, said process comprising:
reacting a nitrite ester of said polyhydroxy polymer and polyvinyl alcohol with nitric acid at a temperature of 60 to 110°C

28. The process of claim 27 wherein said polyhydroxy polymer is cellulose.

29. A process as claimed in claim, 1 for preparing a sulfate ester of a polyhydroxy polymer which is a polysaccharide or a polyvinyl alcohol that is partially substituted with at least one of ether and ester groups, said process comprising:
reacting a nitrite ester of said polyhydroxy polymer with sulfur trioxide or a complex thereof at a temperature ranging from 0 to 25°C. to obtain a mixed nitrite:sulfate ester of said polyhydroxy polymer;
reacting said mixed ester with a protic solvent to remove re-sidual nitrite ester groups from said polymer; and reacting said polymer with a base to neutralize or slightly alkalize said polymer and to obtain said sulfate ester in the form of its salt.

30. The process of claim 29 wherein said polyhydroxy polymer is cellulose.

31. The process of claim 29 wherein:
said nitrite ester has a degree of substitution of 2 to below 3; and said cellulose sulfate ester has a degree of substitution ranging up to 1.1.

32. The process of claim 29 wherein:
said nitrite ester has a degree of substitution which is less than 2;
said cellulose sulfate ester having a degree of substitution greater than 1.1; and the sum of the degree of substitution of said cellulose sul-fate ester and the degree of substitution of said nitrite ester is equal to 3.0 minus the D.S. from ester or ether groups originally present.

33. A process as claimed in claim 1 for preparing a substantially uniformly substituted cellulose sulfate having a degree of substitution of 1.1 to 2.0 which is colloidal and is compatible with potassium ions in an aqueous media without gellation of the cellulose sulfate and a viscosity in-crease in the aqueous media, said process comprising:
reacting a nitrite ester of cellulose having a degree of substitution which is less than 2 with sulfur trioxide or a complex thereof at a reaction temperature of 0 to 25°C. to obtain a mixed nitrite:sulfate ester of cellulose in which the sum of the degree of substitution of nitrite ester groups and the degree of substitution of sulfate ester groups is equal to 3.0;
reacting said mixed ester with a protic solvent to remove re-sidual nitrite ester groups from said cellulose; and reacting said cellulose with a base to neutralize or slightly alkalize said cellulose and to obtain said cellulose sulfate in the form of its salt.

34. A process as claimed in claim 1 for preparing a substantially uniformly substituted cellulose sulfate having a degree of substitution ranging up to 1.1 which is water soluble or water swellable, said process comprising:
reacting a nitrite ester of cellulose having a degree of sub-stitution of 2 or 3 with sulfur trioxide or a complex thereof at a reaction temperature of 0 to 25°C. to obtain a mixed nitrite:sulfate ester of cellulose;
reacting said mixed ester with a protic solvent to remove re-sidual nitrite ester groups from said cellulose; and reacting said cellulose with a base to neutralize or slightly alkalize said cellulose and to obtain said cellulose sulfate in the form of its salt;

35. The process of claim 34 wherein said cellulose sulfate is water soluble and has a degree of substitution of 0.3 to 1.1.

36. The process of claim 34 wherein said cellulose sulfate is water insoluble but is highly swellable in the presence of water and has a degree of substitution of up to 0.3.

37. A process for preparing a sulfate ester of cellulose as claimed in claim 1, including the steps of:
reacting a nitrite ester of cellulose with sulfur trioxide or a complex thereof at a reaction temperature of 0 to 25°C. to obtain a mixed nitrite:sulfate ester of cellulose;
reacting said mixed ester with an alcohol containing up to 10 carbon atoms; and said alcohol reacting with the nitrite groups in said mixed ester and also with any free dinitrogen tetroxide to produce an alkyl nitrite and to free the mixed ester of nitrite groups.

38. A process for preparing a sulfate ester of cellulose as claimed in claim 1, said process including:
reacting a nitrite ester of cellulose with sulfur trioxide or a complex thereof at a reaction temper-ature of 0 to 25°C. to obtain a mixed nitrite:
sulfate ester of cellulose- adding water to the said reaction mixture with said water reacting with the nitrite ester groups in said mixed ester and also with any free dinitrogen tetroxide; and neutralizing the sulfuric acid ester of cellulose through addition of an inorganic base to produce a mixture of an in-organic nitrate in addition to producing said sul-fate ester of cellulose.
39. A cellulose sulfate ester having a degree of substitution of up to 0.3, said ester being water-insolu-ble but highly swellable in the presence of water, and the sulfate ester groups in said ester being substantially uniformly distributed among the polymer units of the cel-lulose.
40. A water-soluble colloidal cellulose sulfate ester having a degree of substitution of 1.3 to 2;
said sulfate ester groups being substantially uni-formly distributed among the polymer units of the cellu-lose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, Al, Zn, Ni++, Co++,Cu++,Cd, Fe++, Cr+++, Pb, Hg++, Ag and Sn++ ions.
41. The ester of claim 40 in the form of a thickened aqueous medium containing water and said sulfate ester of cellulose with said sulfate ester being present in an effective amount to thicken said aqueous medium.

42. A water-soluble colloidal cellulose sulfate ester;
said sulfate ester having a degree of substitution of 1.0 to 1.3;
said sulfate ester having a substantially uniform distribution of sulfate ester groups among the polymer units of the cellulose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, Al, Zn, Ni++, Co++, Cu++, Cd, Fe++, Cr+++, Pb, Hg++, Ag, Sn++, Ba, Fe+++ and Ce+++ ions.
43. The ester of claim 42 comprising a thickened aqueous medium containing water and said sulfate ester of cellulose, with said sulfate ester being present in an effective amount to thicken said aqueous medium.

18. The ester of claim 12 comprising a polymeric nitrate ester formed from said ester (a) by the complete elimination therefrom of nitrite ester groups, whereby all said ester groups and nitrate groups, wherein ni-trate ester groups are substantially uniformly distributed among the polymer units of said polyhydroxy polymer.
19. The ester of claim 12 wherein said polyhydroxy polymer is a polysaccharide or a polyvinyl alcohol.
20. The ester of claim 18 wherein said polyhydroxy polymer is a polysaccharide of polyvinyl alcohol.
21. The ester of claim 10 or 20 wherein said polysaccharide is cellulose.
22. The ester of claim 18 comprising a thickened aqueous medium containing water and said water-soluble nitrate ester, with said water-soluble nitrate ester being present in an effective amount to thicken said aqueous medium.
23. The ester of claim 22, wherein said polyhydroxy polymer is cellulose.
24. A water-soluble colloidal sulfate ester of cellulose having a degree of substitution of 0.3 to 1.0;
said sulfate ester having a substantially uniform distribution of sulfate ester groups among the polymer units of the cellulose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, Al, Zn, Ni++, Co++, Cu++, Cd, Fe++, Cr+++, Pb, Hg++, Ag, Sn++, Ba, Fe+++ and Ce+++ ions.
25. The esters as claimed in claim 24 in the form of their metal salts.
26. The esters of claim 24 in the form of a thickened aqueous medium containing water and said water-soluble sulfate ester of cellulose, wherein said sulfate ester is present in an effective amount to thicken said aqueous medium.

38. A process for preparing a sulfate ester of cellulose as claimed in claim 1, said process including:
reacting a nitrite ester of cellulose with sulfur trioxide or a complex thereof at a reaction temperature of 0 to 25°C.
to obtain a mixed nitrite:sulfate ester of cellulose;
adding water to the said reaction mixture with said water reacting with the nitrite ester groups in said mixed ester ' and also with any free dinitrogen tetroxide; and neutralizing the sulfuric acid ester of cellulose through addition of an inorganic base to produce a mixture of an in-organic nitrite with an inorganic nitrate in addition to pro-ducing said sulfate ester of cellulose.

39. A cellulose sulfate ester having a degree of substitution of up to 0.3, said ester being water-insoluble but highly swellable in the presence of water, and the sulfate ester groups in said ester being sub-stantially uniformly distributed among the polymer units of the cellulose.

40. A water-soluble colloidal cellulose sulfate ester having a degree of substitution of 1.3 -to 2;
said sulfate ester groups being substantially uni-formly distributed among the polymer units of the cellu-lose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, Al, Zn, Ni++, Co++, Cu++, Cd, Fe++, Cr+++, Pb, Hg++, Ag and Sn++ ions.

41. The ester of claim 40 in the form of a thickened aqueous medium containing water and said sulfate ester of cellulose with said sul-fate ester being present in an effective amount to thicken said aqueous medium.

42. A water-soluble colloidal cellulose sulfate ester;
said sulfate ester having a degree of substitution of 1.0 to 1.3;
said sulfate ester having a substantially uniform distribution of sulfate ester groups among the polymer units of the cellulose, and said sulfate ester being compatible and non-gelable in an aqueous medium in the presence of NH4, Na, K, Mg, Ca, Sr, Al, Zn, Ni++, Co++, Cu++, Cd, Fe++, Cr+++, Pb, Hg++, Ag Sn++, Ba Fe+++ and Ce+++ ions.

43. The ester of claim 42 comprising a thickened aqueous medium containing water and said sulfate ester of cellulose, with said sulfate ester being present in an effective amount to thicken said aqueous medium.