CA1051880A - Esters of polyhydroxy polymers and processes for their preparation - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Processes are provided for preparing esters of polyhydroxy polymers.
Examples of suitable such esters include nitrate esters, sulfate esters, colloidal cellulose sulfate, substantially uniformly substituted cellulose sulfate, nitrate esters of cellulose, nitrate or sulfate esters of a poly-saccharide or polyvinyl alcohol in admixture with an alkyl nitrite, and a mixture of a nitrate or sulfate ester of a polysaccharide or polyvinylalcohol and an inorganic nitrite. The heart of the process involves first preparing a nitrite ester and then reacting the nitrite ester to provide another ester.
Also provided herein are polysaccharide or polyvinyl alcohol containing a mixture of nitrite ester groups with sulfate or nitrate ester groups, water soluble nitrate esters of a polysaccharide or a polyvinyl alcohol, a thickened aqueous medium containing water and a water soluble nitrate ester of a poly-saccharide or a polyvinyl alcohol, a water soluble sulfate ester of cellulose, a water insoluble but water swellable sulfate ester of cellulose, and a thick-ened aqueous medium containing water and a water soluble sulfate ester of cellulose.

Description

1051880 ~ ~, This invention relates to ester derivatives of polyhydroxy~
polymers, to process for their production, and to the uses thereof. ~ ~ o Ester derivatives 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 (herein-after 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 relatively uniform. This has produced ester derivatives whose properties, e.g., water solubility and compatability with various metallic ions, have not been generally satisfactory and has restricted the use areas for the ester derivatives.
Esterified polyhydroxy polymers may be prepared from nitrite esters of the polyhydroxy polymers. The nitrite esters are employed as reaction 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 interme-diates, polymeric products, such as, for example, nitrate esters ~r lOS188~
or sulfate esters of polyhydroxy polymers~ are obtained which have novel properties and a generally uniform substitution of nitrate or sulfate ester groups among the polymer unit~.
Due to the relative instability of the nitrite ester groups, polyhydroxy polymer nitrites may be used also for making films, fibers and other shaped articles consisting of homogeneous mixtures of various polyhydroxy polymers or of one or more polyhydroxy poly~ers and one or more other polymers.
In the formation of an ester derivative of a polyhydroxy polymer, the amount of depolymerization resulting from the reaction is negligible. Thus, products are obtained which have very high solution viscosities. In the case of sulfate esters of polyhydroxy polymers, products have been obtained whosè solution viscosities are many times greater than the solution viscosities of superficially similar æulfate esters produced by prior art methods.
In addltion, it is possible 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 prepared having a low D.S., e.g., less than 0.3 in which the ester groups are substantially uniformly distributed among the cellulose polymer units.
Also, sulfuric acid esters of locust bean gum and guar gum have been obtained whieh have a D.S. of above 1. Still further, water soluble nitrate esters of polyhydroxy polymers have been prepared having a D.S, of less than 1. The properties of these nitrate ~ 2~ ~
i, ,, .. . . . .

esters are especlally surprising since prevouS nitrate esters of polyhydroxy polymers have, in general, been highly substituted and insoluble in water, The relatively uniform distribution of the ester substituent groups over the macromolecule obtainable herein results, in part, from the fact that the polymeric nitrite intermediate used in the reaction is solvated or even dissolved in the reaction medium. In contrast, in prior art methods, the polymeric starting material was generally suspended in the reaction medium in the form of insoluble particles. The homogeneity of the products prepared herein is of particular importance when the D.S. of the esterified products is considerably below the maximum D.S. for the particular polyhydroxy polymer, such as, for example, in the sulfate esters of an aspect of this invention and particularly in the case of the cellulose sulfate esters.
~or example~, in previous sulfation procedures, e.g., in preparation of cellulose sulfate esters, insoluble cellulose fiber was used as the starting material. In sulfating the fiber, the reaction mechanism involYed the so-called "Peeling Process", in which the fiber surface was first partially substituted, then solvated and removed by the reaction medium, and then highly substituted by reaction with excess sulfation reagent in the reaction medium. During the "Peeling Process", the next inner layer of the cellulose fiber was then exposed and sulfated in a similar fashion with the process proceeding until most of the fi~er or the sulfation reagent was consumed.

.~ ~

As a ~esult o~ the ~Peeling P~ocess~ the poly-meric sulfates which were previously ohtained were highly substituted and had a D,S, relatively close to the maximum for the polymer irrespective of the amount of sulfat~on reagent employed. Even when the average D.S, of the polymer was less than the maximum D.S. of the polymer, the distribu-tion of ester su~stituent groups was not uniform and a considerable nu~ber of the polymer units were fully substituted while other polymer units had a very low D.S.
or were not substituted at all. In the process of one aspect of the present invention the nitrite ester used as an intermediate is solvated or solubilized and the ester substituent groups in the final product are, thus, distributed substantially uniformly among the polymer units of the product. Thus, in cellulose sulfate products of one aspect of this invention having a D.S. of 2 or 1, substantialIy all of the polymer units in the cellulose will contain only two sulfate ester groups or one sulfate ester group.
Due to the substantially uniform distribution of ester groups among the plolymer units in the products of aspects of the present invention, the products have, in general, unusual solubility characteristics. Also, solutions of the products have unusual compatibilities with metallic ions. For example, cellulose sulfate products provided according to an aspect of this invention which have a D.S.
of 0.3 to 1 are soluble in water. This is quite surprising since the prior literature reports that colloidal cellulose sulfate must have a D,S. in excess of 1 in order to be water soluble, ~ S~~
~..- . .

In addition, sulfate esters of polyhydroxy polymers of an aspect of the present invention 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 compati6ilities with relatively high concentrations ~, of metallic ions. Still further differences are observed between the products of aspects of the present invention and superficially similar materials of the prior art, e.g., r sulfates of polyhydroxy po]ymers, in terms of reactivity 10with water soluble proteins.
As disclosed in my prior copending application Serial No. 230,049, filed ~June 24, 1975 one aspect of that invention was directed to a process for the preparation of nitrate esters or sulfate esters of a polyhydroxy polymer which was a polysaccharide or a polyvinyl alcohol that was partially substituted with ether or ester groups. ~therified and esterified polysaccharides or polyvinyl alcohol are known materials which may include, for example, substituent groups p such as formate, acetate, carboxymethyl, methyl ether, ethyl ether, and propionate groups. Typical of the known etheri-fied and esterified materials which may be employed as starting materials are carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, alginic acid acetate, alginic acid propionate, starch phosphate, hydroxypropyl guar, pectic acid butyrate, carboxymethyl starch, partially Y`
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 nltrate or sulfate esters of etherified or esterified polysaccharides or poly~inyl alcohol, according to aspects of the present invention, 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 accord with aspects of this 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, nitra-tion, and sulfation of the unsubstituted polyhydroxy polymers to provide the corresponding ester derivatives of the partially ethèrified or esterified polyhydroxy poly~ers.
The nitrite esters of polyhydroxy polymers, employed as reaction intermediates in the process of aspects of the present invention, are prepared by nitrosating a suspen-slon 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 sulfate esters of polysaccharides and polyvinyl alcohol can be readily synthesized in accord with aspects of the present invention. The resulting nitrate and sulfate ester products show a negligible degree of depolymerization and a selective degree of esteri-fication. Also, the nitrate and sulfate ester products are distinguished by their homogeneity of ~_ , ... .

105~880 substitution, i,e,? the ester groups, such as7 fo~ examp]e, sulfate ester groups, are relati~ely homogeneously distributed over the macromolecule. 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 lons.
Water soluble nitrate esters may be easily prepared from the corresponding nitrite esters in accord with other aspects of this invention 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 nitrate 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 accord with-other aspects of the present invention by sulfating the nitrite ester of a polysaccharide or polyvinyl alcohol with sulfur trioxide or a complex thereof at a relatively low reaction temperature. 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 ester.
The undegraded alkali ester salts are highly soluble and their aqueous solutions possess a high viscosity. Thus, the sulfate ester salts are useful as thicke~ers in aqueous media.

10518~0 Typical of known polyhydroxy polymers ~hich may be utilized as starting materials are the polysaccharlde~
such as, for example, cellulose, starch, hemicellulose, guar gum, locust bean gum, gum arabic and the mannans; the polyuronic acidæ
typified by alginic and pectic acids, and the synthetic polyhydroxy polymers such as, for example, polyvinyl alcohol. In accord with one aspect of the invention, the partially etherified or esterified polyhydroxy polymers, as described previously, are used as starting materials in the preparation of nitrate esters or sulfate esters of the partially substituted polyhydroxy polymers.
The starting polyhydroxy polymer is suspended in a suitable solvent which includes a swelling or solubilizing agent for the`polymeric reaction product and a proton acceptor. Solvents which have been found suitable in serving both as a proton acceptor and a swelling or solubilizing agent include weak tertiary amine base as typified by pyridine, quinoline and isoquinoline and also N,N-dialkyl acylamides such as N,N-dimethylformamide and N,N-dimethylacetamide (hereinafter referred to as DMF and DMAC respectively), and mixtures thereof. Suitable swell-ing or solubilizing agents are generally solvents which are capable of dissolving polymeric esters. Typical examples of such swelling or solubilizing agents are ethyl acetate, ethyl formate, benzene, acetone, methyl ethyl ketone, and the like and mixtures thereof. Compounds which are suitable as proton acceptors are those, as previously described, which are capable of providing 60th swelling or solubilizing of the polymeric nitrite ester and also acting as a proton acceptor.

10511~80 1 The amount of solvent which may be utilized to

2 suspend the polyhydroxy polymer is not critical and may be

3 varied over a relatively wide range, Howe~er, 3ufficient

4 solvent should ~e used to avoid difficulty in handling the resulting viscous mixture. In general, it has been found 6 that a minimum solvent to polymer weight ratio is 3:1, 7 i.e., three parts by weight of solvent for each part of 8 polymer.
In general, it is preferable that the solvent be 11 capable of both swelling or solubilizing the resulting poly-12 hydroxy polymer nitrite ester and also acting as a proton 13 acceptor. The use of a single solvent, as opposed to use 14 of a mixture of a proton acceptor with a swelling or solubilizing ayent, provides process economies since it 16 simplifies the recovery and the reuse of the ~olvent material.
17 However, should a mixture of a proton acceptor with a swelling 18 or a solubilizing agent be employed, it is necessary that the 19 mixture contain at least one mole of the proton acceptor for each mole of the nitrosating agent, e.g., dinitrogentetroxide.
21 -:
22 As stated, when a nitrite ester is nitrated or 23 sulfated in accord with the invention, the product which 24 is obtained is a novel polysaccharide or polyvinyl alcohol which contains a mixture of nitrite ester groups with 26 sulfate or nitrate ester groups with the mixture of groups 27 being substantially uniformly distributed among the polymer 28 units in the polysaccharide or polyvinyl alcohol, These 29 novel products are valuable intermediates in the preparation of a sulfate or nitrate ester of a polysaccharide or poly-_, .. . . .

1051~80 vinyl alcohol in which the sulfate or nitrate eater groups are substantially uniforQly distributed among the polymer units in the polysaccharide or polyvinyl alcohol, 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 substitu-tion of 2 to 3; the cellulose sulfate ester which is produced in accordance`with an aspect of this 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 2, the cellulose 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 substitution of the nitrite ester is equal to 3Ø
A further aspect of the invention 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 distributed 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 methods, are not water soluble unless the degree of substitution is in excess of 1Ø In the ~ ,.

usage of these water soluble sulfate este~s of cellulose, a further aspect of the invention concerns a thickened aqueou8 medium which contains water and a water soluble sulfate ester of cellulose having a degree of substitution of 0.3 to about 1.0 with the sulfate ester groups being substantially uniformly distrlbuted among the polymer units of the cellulose and the cellulose sulfate ester being present in an effective amount to thicken the aqueous medium.
A still further aspect of the invention concerns water insoluble esters of cellulose which are, however, highly swellable in the presence of water. These water insoluble cellulose sulfate esters have a degree of substitution of less than 0.3 with the sulfate ester groups being substantially uniformly dis`tributed among the polymer units of the cellulose.
The water swellability of 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.
A further aspect of the invention concerns nitrite esters of a polysaccharide or polyvinyl alcohol having a degree of substitution of less than 2Ø In particular, the nitrite esters of cellulose having a degree of substitution of less than 2.0 are of unique value since they may be employed in forming cellulose sulfate esters , as described, having a degree of substitution of 1.1 to 2.0 with the sum of the degree of substltution of the nitrite ester groups and the degree of substitution of the sulfate ester groups in the precursor mixed ester being equal to 3.0, J
. .

10~880 A still further aspect of the inYention concerns novel water soluble nltrate esters of a polysacchar~de or a polyvinyl alcohol having a degree of substitution of less than 1.0 in which the nitrate ester groups are substantially uniformly dis-trlbuted among the polymer units of the polysaccharide or poly-vinyl alcohol. The properties of these materials are unique in that nitrate eæters produced by prior art procedures are highly substituted and water insoluble.
As a corollary to the unique water soluble nitrate esters of a polysaccharide or a polyvinyl alcohol, a further aspect of the invention concerns a thickened aqueous medium containing water and a water soluble nitrate ester, as des-cribed, having a degree of substitution of less than 1Ø
The nitrate ester groups are substantially uniformly distri-buted among the polymer units of the polysaccharide or poly-vinyl alcohol and the water soluble nitrate ester is present in an effective amount to thicken the aqueous medium.
A still further aspect of the invention concerns an improved process for the preparation of nitrite esters of cellulose. As described, the usage of a nitrite ester inter-mediate of cellulose makes possible the preparation of novel cellulose esters, such as, for example, cellulose sulfate or cellulose nitrate, in which the properties of the final product may be attributed to the substantially uniform distribution of ester groups among the polymer units of the cellulose. It has been found that the nitrosation of cellulose with dinitrogentetroxide or nitrosyl chloride, and the subsequent sulfation as described previously, may be even further improved if the cellulose reactant is in an , acti~ated state o~ suit~bly actlyated, In acco~d with the impro~ed process, the cellulose reactant is in a hydrated form and contains from 4 to 12 per cent by weight of water with the water being ~ubstantlally uniformly distributed throughout the cellulose reactant.
In using the hydrated cellulose as a reactant, the nitrosation reaction can be carried out in a shorter time with the use of essentially stoichiometric amounts of the nitrosa-tion reactant. This produces a more homogeneous reactio~n mixture, a higher clarity product and, thus, permits easier separation of the product from the reaction mixture and reduces the need for filtration A still further aspect of the invention concerns a variation of the improved nitrosation process in which the cellulose reactant is substantially uniformly hydrated. In this variation, a hydrated cellulose which may contain in excess of 4 per cent by weight of water distributed substantially uniformly throughout the cellulose is washed with a highly polar aprotic solvent to reduce the water content of the cellulose to less than 4 per cent by weight. Surprisingly, it has been found that the cellulose remains in an activated state after washing with the aprotic solvent, even though the washed cellulose has a water content less than 4 per cent by weight. The washed cellulose can then be employed in the manner described previously for nitro-sation with dinitrogentetroxide or nitrosyl chloride.

_ ~_ ~ ~, , ~05~380 In a stlll ~urther aspect of the inyention? 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 ~ormation of cellulose nitrate or cellulose sulfate esters.
In forming an alkyl nitrite ester as a by-product in accord with another aspect of this invention, an alkyl alcohol is added to a~reaction mixture containin~ a mixed nitrite:nitrate or a mixed nitrite:sulfate ester of a polysaccharide or a poly-vinyl alcohol. Since the mixed ester is 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 nitrite groups on the polysaccharide or polyvinyl alcohol. The reaction of the dinitrogentetroxide with the 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 _ ~_ b nitrite substituent groups on the polysacch~ide o~ poly-vinyl alcohol with the alkyl alcohol occurs through a transesterification reaction rather than a direct nitrosa-tion. 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.
~atever the reaction mechanism ~ay be, it is most 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 ~he 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 contain-ing up to 10 carbon atoms. 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 reaction. In order to utilize the dinitrogentetroxide reagent quantitatively in the reaction, the alkyl alcohol reactant should be present in an amount of at least one mole of alkanol or one-half mole of alkanediol for each mole of dinitrogentetroxide which is initially added in forming the nitrite ester of the polysaccharide or polyvinyl alcohol lOS181~0 inte~mediate with the alcohol belng added afte~ for~ation of the mixed polysaccha~ide or polyvlnyl alcohol este~, Since alkyl nitrite esters are relatively stable in comparison to the nitrite es~ers of polysaccharides or polyvinyl alcohol, the further reaction steps in forming the primary nitrate or sulfate ester product, i.e,, neutra-lization, 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 nitrite:
sulfuric acid ester of cellulose with subsequent addition of the required amount of alcohol, the resulting sulfuric acid ester of cellulose may be precipitated by addition of acetone to th~ 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 maj 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 distil-20; lation to minimize decomposition of the various compounds.
As an additional way to minimize decomposition, 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 pre-ferred 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 '~C ~
~.., ;

~051880 decompogltion of the alkyl nit~ite by~p~oduct has been obseryed wh n t~e product recovery i8 carried out in this manner, Thu6, after addltion of the alkanol or alkanediol, a suitable base, such as, for example, the ammonlum and N-substituted ammonium, alkali, or alkaline earth hydroxides, carbonates, or bicarbonates is added as an aqueous solution or as a suspension of an excess quantity of base in itfi saturated solution with continuous mixing of the reaction mixture during addition of the base. The preferred bases are the alkali carbonates and alkali bicarbonates whlch may be added also in the form of dry powders. To prevent any degradation of the polysaccharide ester product or poly-vinyl alcohol ester product, e.g" the cellulose sulfate ester, the reaction mixture is preferably kept at a temper-ature of below 15-20C. until the neutralization is completed.
If the solids concentration of the reaction mix-ture is sufficiently high and the concentration of water in the mixture is relatively low, the cellulose sulfate ester may be present in a wet solid form and may be readily removed. If, however, the cellulose sulfate ester is in the form of a paste after neutralization, a sufficient quantity of a water miscible solvent, such as, for example, acetone,-methanol-,- ethanol, or isopropanol, is added to cause separ-tion so that the product can be removed, pressed out, and dried or purified further. If the product is dried directly, the resulting product is a technical, relatively crude grade product which contains salt as the principal impurity. A
purified product may be prepared by extracting the wet solids - ,2~ _ 105~880 one or more times wlth an aqueous alcohol, such aS? for example~
methanol, ethanol, or isopropanol containing 20_40 per cent by weight of water, ~ollowed by drying of the product at an elevated temperature, Of course, it is also possi61e to extract the dried technical grade product with aqueous alcohol to arrive at a refined grade.
The flltrate, 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 contain~
ing less than 20% of water. This will 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 absorbed solvents, including any retained alkyl nitrite, can be recovered.
A second by-product which may be formed in equi-valent a unts iR an inorganic nitrate, for example, sodium nitrate, if sodium hydroxide or -sodium carbonate was used for neutralization. If it is not desired that an alkyl nitrite ester be produced simultaneously with production of the inorganic nitrate, an equivalent amount of water may be added to the reaction mixture instead of adding an alkyl /g _ ,~ _ - 105~380 alcohol, This ~i~ll then result in the for~at~on o~ equi~alent amounts of inorganic nitrate and nitrite, such ~s, for exa~ple, 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 ~ay be purified by crystallization or other known methods to provide salts of medium or hlgh purity. However, if the salts are to be used as fertilizers, additional purifica-tion may not be necessary.
The first step of a process in accordance with one embodiment of this invention comprises nitrosating a poly-hydroxy polymer suspended in a suitable solvent with dinitro-gentetroxide, nitrosyl chloride or mixtures thereof to obtain the corresponding polyhydroxy polymer nitrite ester.
The`nitrosating compound is used in the reaction mixture at a molar ratio of anhydroglucose or generally polymer unit to dinitrogentetroxide or nitrosyl chloride of 1:0.1 to 1.3, resulting in a D.S. of 0.1 to 3. Since the reaction is quantitative, the D.S. approximately coin-cides with the molar amount of nitrosatlng agent used. If nitrosyl chloride is used in combination with DMF or D~AC, a 2.5 to 3.0-fold excess of the nitrosating reagent is required to attain these D.S.'s. Stated another way, one mole of dinitrogentetroxide or nitrosyl chloride is neces-sary to replace one mole of hydroxyl radical of the polyhydroxy polymer, and if nitrosyl chloride is used with an N,N-dialkyl acidamide as the proton acceptor, 2.5-3.0 les of nitrosyl chloride are required~

. . , ~CJ ~

lOS~880 The maximum D.S. for hexo$ans? such as? fox example~ cellulose, starch, guar and locust bean gums, mannans, and the like is about three; for pentosans, such as, for example, hemicellulose, and polyuronic acids, such as, for example, alginlc and pectic acids, it i8 two; and for polyvinyl alcohols the maximum D.S. is one or less. Thus, the molar amount of dinitrogentetroxide necessary to obtain complete esterification for hexosans is three moles per mole of anhydrohexose unit, for pentosans and polyuronic acids two moles per mole of anhydropentose or uronic acid units, and for polyvinyl alcohols one mole or less depending upon the degree of saponification of the starting compound. The same mole ratio amount of nitrosyl chloride is necessary for complete esterification of each of the hereinbefore described classes of polyhydroxy polymer unless DM~
or DMAC is us`ed 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 nitrosation reaction is preferably carried out with constant 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 like since the reaction is moderately exothermic, , 2 l(~S1880 and it ls desixable to maintain the te~pe~atu~e of the reaction mixture below 50CC, If maximum esterification is desired, completeness of the reaction is indicated by the for~ation 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 polymeric nitrite esters are relatively sensi-tive 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.
This results in the regeneration of the undegraded polyhydroxy polymer starting material.
Since the polymeric nitrite esters find their primary utility as intermediates in the production of other ester deri-vatives, such as, for example, polymeric nitrate and sulfate esters and the like, there is no need to isolate the nitrite esters as the reaction mixture may be used for those processes, as hereinafter described. However, the polymeric nitrite esters may be isolated by neutrali~ing the reaction mixture by the addition of a base, such as, for example, mono-, di-, and tri-alkylamines, pyridine, alkali or alkali earth metal hydroxides, carbonates, bicarbonates, or the like. The addition of such a base-is-necessary only if an N,N-dialkyl acylamide had been used as the proton acceptor since, during nitrosation with dinitrogentetroxide or nitrosyl chloride, an equimolar _ ~ _ ~.~

105~880 amount of nitric acid or hydrochloric acid is formed, If a weak tertiary amine base, such as, for exa~ple, pyridine or quinoline, had been used as the proton acceptor, the addition of a base is unnecessary since, then, the acid formed is neutra-lized by the tertiary amine base and cannot serve as a catalyst for the decomposition of the polymer nitrite.
The neutralized, or preferably slightly alkaline solution is then added to ice cold water with stirring to separate the polymeric nitrite ester as a fibrous material, which may be easily removed. Those products with a D.S.
considerably below the 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 it is preferred that it be solvated in a suitable solvent such as, for example, benzene, ethylacetate, ethylene d~chloride, DMF, DMAC, or the like and stored at a low temperature, preferably below 10C.
In forming a nitrate ester product, the second step of the process of an aspect of this inYention comprises heating the polymer nitrite ester so]ution in the presence of nitric acid 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 polymeric nitrite ester solution used in step 2 is generally the reaction mixture formed ~,i _ ~ _ - .

in step 1~ in which DMF or DNAC has been used as the proton acceptor and dlnitrogentetroxide as the reagent in an amount sufficient for nitrosation to about the maximum D,S.~ the polymeric nitrite ester may be isolated after step 1 and then redissolved in one of the solvents, as stated above, and the corresponding amount of anhydrous nitric acid added, The use of the reaction ~ixture of step 1 for step 2 obviates the need for isolation of the polymeric nitrite ester as herein-before described. Also, the addition of nitric acid during step 2 is not necessary in this case since, during nitrosa-tion with dinitrogentetroxide in DMF or DMAC, enough nitric acid is formed for the subsequent nitration.
Subsequent to heating, the polymeric nitrate ester is isolated by pouring the reaction mixture slowly and with agitation into two to five volumes of a water miscible protic solvent, such as, for example, methanol, ethanol, isopropanol, and the like, which splits off residual nitrite groups and separates the resulting product. The product is then filtered off, washed with fresh solvent and dried.
; The resulting nitrate ester product is water soluble, and aqueous solutions of the ester tolerate rela-tively high concentrations of water miscible organic solYents such as 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. Purther, the solutions of the polymeric nitrate esters have a relatiYely high viscosity and owing to .
"

- ~051880 their golubillty X i~proyed hydration in wateX and aqueous organic solvents, their usefulness is enhanced, To for~ the polymeric sulfate ester, step 2 as previously defined is omitted and alternatively, the next process step comprises sulfating the polymeric nitrite ester solution, preferably with a sulfur trioxide solvent complex, at a low temperature to obtain a polymeric mixed nitrite:sulfuric acid ester.
The polymeric nitrite ester solution preferably comprises the reaction mixture of step 1, in which a N,N-dialkyl acylamide has been used as the proton acceptor.
The temperature of the reaction mixture should be maintained in the range from 0C.-25C., and preferably 5-15DC. to prevent depolymerization of the molecule during sulfation.
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 carbontetrachloride. However, since the addition of sulfur trioxide is very exothermic and a low reaction temperature is critical to obtaining the desired viscosity in the product, the sulfur trioxide must be added slowly with stirring, while maintaining the reaction mixture in a cooling medium such as 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 reaction mixture to facilitate , ~ .., i(~Sl~80 solyent recoye~y? to fo~ a complex which upon addition to the re~ction mixture produces a less exothermic seaction, Examples of solvents capable of formlng a complex with sulfur trioxide are DMF, DMAC, dlo~ane and pyridine. Gen-erally, the mole ratio of the sulfur trioxide to the solvent in the complex is 1:1. However, it is preferable to use an excess of the solvent to obtain a suspension or solution of the complex in the excess.
The complex is slowly added to the reaction mix-ture with agitation and exclusion of moisture. The amount of sulfating agent to be added to the mixture is dependent upon the D.S. desired in the resulting product. A low D.S.
value ranging between 0.1 to 1.0 requires 0.1 to 1.0 mole of sulfu~ trioxide per mole of anhydroglucose unit.
A D.S. value ranging from 1.0 to 2.0 requires 1.0 to 4.0 mole of sulfur trioxide per anhydroglucose unit. A D.S.
exceeding 2.0 i8 difficult under the reaction conditions, and a large excess of sulfur trioxide is required.
The addition of the sulfating agent to the polymer nitrite ester mixture forms a mixed polymeric nitrite:sulfuric acid ester. Although the polymeric nitrite ester with a maxi-mum D.S. may be used for the sulfation to obtain products with a degree of sulfation of up to 1.1, it is preferred to ~ ~ ~ 0 use the lower D.S. polymer nitrites for economic reasons and ~ ~ ~
b~b ~ S
particularly where a D.S. of about 1.1 is desired. k 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 1, Howeyer, if the degree of nitrosation S~
's:, ., _ ~ _ 105~880 drops considerably below l? sulfation beco~es inc~easingly more difficult and incomplete and the dlstribution of the sul-fate groups non-uniform. Generally, the higher the degree of sulfation desired, the lower may be the degree of nitrosation such that the mixed polymer nitrite sulfuric acid ester has a maximum D.S. I~ other words, the sum of the degree of nitrosa-tion and the degree of sulfation should be 3 for the hexosans, 2 for pentosans and polyuronic acids, and 1 or less for the polyYinyl alcohols.
The next step of the process of an aspect of this invention comprises reacting the mixed polymeric nitrite:sulfuric acid ester with a protic solvent to obtain the corresponding polymeric sulfuric acid ester.
The~addition of a protic solvent such as, for example, water, methanol and ethanol results in the production of the pure polymeric sulfuric 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 polymeric sulfate ester product, two to four volumes of a water miscible solvent, i.e., acetone, is added to the mixture to separate the sulfated polymer therefrom. The ester is removed and washed with fresh solvent, and redissolved in ice water.
The next step of the process of an aspect of this invention comprises neutralizing the polymeric sulfuric acid ester with a base to form a salt thereof.

,~

,~, -- ~ _ ~05~880 The lsolated polymeric suluric ~cid ester will degrade upon storage and therefore it is preferable to conyert it to a neutral salt, The preferred bases for neutralizing the sulfate ester are the hydroxides, carbon~
ates and bicarbonates of the alkali and alkaline earth metals, while ammonium hydroxide and the amines are like-wise useable for this purpose. 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 isolated product may be washed with an aqueous solvent and dehydrated by washing with anhydrous solvent. The separated polymeric sulfate ester salt may then be removed and dried for storage.
Ins~tead of neutralizing an aqueous solution of the isolated polymeric sulfuric acid ester, the polymeric sulfuric acid ester-protic solvent reaction mixture of the previous step may be neutralized directly to obtain the polymeric sulfate ester salt. In this case, the base may be added as an aqueous solution or in its dry form. In the neutralized mixture, the product may be present in wet, but solid, form and may be removed directly by centrifuga-tion or filtration, 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 product one or more times with aqueous alcohol prior to drying. If there is a relatively large amount of water in the neutra-lized mixture, the product may be too soft to be removed or it even may be partially dissolved. In this case, enough alcohol is added to harden the product somewhat or to pre-cipitate it, so it can then be filtered off or centrifuged.

~051881~

1 The product ~s water soluble and since it does 2 not undergo depolymerization, a 1% a~ueous solution produces 3 a very viscous and stable solution. The sodium sellulose 4 sulfate esters become water soluble if the D.S. excee~s 0.3 and have viscosity measurement of as high as 8000-6 9000 cps.
8 As a result of this unique physical property, the 9 products exhibit utility as thickening, suspending and emulsifying agents. Generally, the viscosity decreases 11 somew~at as the D.S. increases simply because of the addi-12 tional weight to the polymer. However, in the application 13 in bone glue~it is preferred to use a product havin~ a D.S, 14 of above 1.0 since in this particular use, best results are obtained with the higher D.S. products.
16 ~
17 The following examples illustrate specific pre-18 ferred embodiments of this invention and are not intended 19 to be limiting. All ratios in the following examples as well as in the specification and in the appended claims 21 are by weight unless otherwise indicated, and temperatures 22 are expressed in degrees centigrade.

A. Preparation of Cellulosé Nitrite Ester from Cellulose 27 20 g. of ~hatman cellulose powder, CF.II, was 28 dried overnight at 110C. and placed in a three necX, round 29 bottom flask equipped with a mechanical stirrer and calcium chloride tu~e. 200 ml of N,N-dimethylformamide (DMF) was ~ ,~ ., I 33 10518~0 .. ...

1 added to the cellulose powder and the mixture was stirred 2 at room temperature. With exclusion of moisture, 3 dinitrogentetroxide (N204) gas was slowly introduced to 4 the mixture over a period of two hours. It was observed that the mixture thickened with about 7-8g. of N204 and 6 that a transparent viscous mixture without any essential 7 development of color was obtained upon introducing approxi-~ mately 15 g. of N204. After introduction of approximately 9 30 g. of N204, the mixture formed a bluish green viscous solution, and on further addition of N204, the color became 11 a deep green while the viscosity appeared to remain constant.

13 To~a sample of the three solutions, an excess of 14 pyridine was added and the slightly alkaline mixture was poured with stirring into ice water. A fibrous precipitate 16 was formed, removed, washed with ice water and pressed out, 17 and the temperature was maintained at 0-5C. The fi~rous 18 precipitate of the first two samples was found to be swell-19 able and that of the third sample was found to be soluble in common solvents for polymer esters including dimethyl-21 formamide, dimethylacetamide, benzene, acetone and ethyl 22 acetate. Upon attempting to dry the fibrous precipitate, 23 the product decomposed as indicated by the reiease of brown 24 fumes. The resulting dried product was found insoluble in the above descri~ed common polymer ester solvents.

27 To identify the resultant products as cellulose 28 nitrite esters and the degree of substitution or esterifi-29 cation (D.S.) thereof, the products were decomposed and cellulose and nitrous acid determinations were made.

~/ ~q 1 Products isolatea from the above three solutions were washed 2 with ice water and suspended in distilled water in a closed 3 ~rlenmeyer flask, acidified with sulfuric acid, and magneti-4 cally stirred at room temperature for 1 hr. The mixture was then neutralized with sodium hydroxide and the insoluble 6 cellulose was regenerated, filtered off, washed with distilled 7 water and dried in vacuo at 100C. The filtrate was collected 8 for testi~g, as hereinafter described.

The identity of the regenerated cellulose was 11 determined by comparison of the regenerated cellulose with 12 the starting material by IR spectrophotometry, negative 13 nitrogen analysis and found identical by the Kjeldahl method, 14 and the absence of carboxyl groups as determined by the method of Samuelson and Wennerblom described in "Methods in 16 Carbohydra~e Chemistry", Yol. III Cellulose, 1963, p. 34.

18 To determine the lacX of depolymerization of the 19 molecule during the reaction and during storage of the reaction medium, th~ viscosity of the regenerated cellulose 21 from reaction mixtures kept over various periods of time, in 22 cuprammonium hydroxide solution was compared with the visco-23 sity of the starting material in the same solution at an 24 identical 0.5% concentration. The viscosities were measured with a Cannon Fenske Viscometer at 25C, The results of the 26 tests are tabulated in the table on the followin~ page.

32 ~!

lOS1880 1 Material Time and Temp. Viscosity~_ ec.
of Storaqe 2 Starting Cellulose Control 28.8 3 Regenerated Cellulose 6 hr. 5C 27.0 4 Regenerated Cellulose30 hr. 5~C 28.8 Regenerated Cellulose120 hr. 5C 28.3 6 Regenerated Cellulose288 hr. 5C 27.8 q 8 The nitrite in the filtrate, as hereinbefore 9 described, was determined by oxidation with permanganate solution to nitric acid. The presence of nitric acid sub-11 sequent to oxidation was established by its determination as 12 nitron nitrate according to the method of Hick described 13 in Analyst, Vol. 59, pp. 18-25 (1934).

The degrees of substitution were calculated from 16 the weight of the cellulose and the amount of nitrous acid, 17 The degree of substitution calculated for the first solution 18 containing about 7-8 g. of N204 was 0.7; the second solution 19 containing about 15 g. of N204 was 1.5 and for the third solution containing about 30 g. of N2O4 was 2.8.

22 Results substantially similar to those obtained 23 above are obtained when the following starting cellulose 24 materials are substituted for Whatman cellulose powder:
cotton linter pulp, celluloses derived from wood or isolated 26 from rice, corn, barley and oat hulls or from bagasse. However, 27 if the foregoing starting materials are used, the amount of 28 DMF used must be increased owing to the higher viscosities 29 of the resulting product~ Partially substituted celluloses, such as methyl or carboxymethyl cellulose can be used also ,.. .

. 10518~0 1 with essentially similar results except that the amount of 2 reagent re~uired for full nitrosation is less because of 3 the smaller num~er of free hydroxyl groups present. Like-4 wise, results sLmilar to those obtained above are obtained when the following solvents are substituted for N,N-dimethyl-6 formamide: N,N-dimethyl acetamide, pyridine, quinoline, and 7 mixtures thereof, or mixtures of one or more of the foregoing 8 solvents and benzene, ethyl acetate, or acetone. It was also 9 found that the dinitrogentetroxide gas could be replaced by its liquid form or a solution thereof in one of the above 11 solvents and by nitrosyl chloride to produ~e substantially 12 similar results.
13 -~
14 Bo PreParation of Cellulose Nitrate Ester from Cellulose Nitrite Ester 17 A dry 500 ml. three-neck, round bottom flask was 18 charged with 9 g. of Whatman cellulose powder, CF II, sus-19 pended in 300 ml. of DMF and solubilized by adding approximately 15 g. of dinitrogentetroxide gas to form 21 cellulose nitrite ester. The cellulose nitrite ester 22 solution was mechanically stirred and heated at 90C. for 50 23 minutes, poured slowly and with agitation into about 6 volumes 24 of methanol to form a precipltate, which was filtered, washed with methanol, and dried.

27 Upon analysis the precipitate was found soluble 28 in water and upon IR analysis showed a strong absorption 29 peak at about 1680 cm~l, each test indicative of nitrate ester groups.

3 ~
_lff _ ~051880 1 ~itrogen determinations by the ~jeldahl method 2 indicated the presence of nitrogen from which a 0.5 degree 3 of substitution was calculated.

The addition of 15 q. of anhydrous nitric acid or 6 24 ml. of acetic anhydride to the cellulose nitrite ester 7 solution prior to heating xevealed that the degree of substi-tution for the resulting cellulose nitrate ester was elevated 9 to 0.8.

11 Results substantially similar to those obtained 12 above are obtained when DMF is substituted by DMAC or by a 13 mixture of DMF or DMAC and benzene or when methyl cellulose, 14 carboxymethyl cellulose or carboxyethyl cellulose is used in place of cellulose.

17 ~X~PLE II
18 A. Preparation of Hemicellulose Nitrlte ~ster from Hemicellulose A 500 ml. three-neck round bottom flask equipped 21 with a mechanical stirrer and calcium chloride tube was 22 charged with 40 g. of hemicellulose extracted from corn hulls 23 and suspended in 300 ml. of DMF. The suspension was mechani-24 cally stirred and under the exclusion of moisture, 58 g. of dinitrogentetroxide gas was slowly introduced to the mixture 26 at room temperature to form a clear viscous solution of ~7 hemicell~lose nitrite ester.

29 ~o a portion of the solution was added-an excess of pyridine and the slightly alkaline solution was slowly 32 ~;
~ 3 1 poured with stirring into ice water to separate a~fibrous 2 precipitate. The precipitate was removed, washed with ice 3 water and pressed out. The resulting precipitate was found 4 soluble in common polymer ester solvents described in Example lA. Upon drying, the precipitate decomposed releas-6 ing brown fumes.

8 Hemicellulose was regenerated for analysis by 9 slowly adding a portion of the remaining hemicellulose nitrite ester solution to four volumes of methanol with 11 agitation forming a precipitate which was filtered, washed 12 with methanol, and dried. The precipitate was identified 13 as hemicellulose ~y IR spectrophotometry and by negative 14 nitrogen analysis by the Kjeldahl method.

16 The lack of depolymerization of the regenerated 17 hemicellulose was determined by preparing ~0 aqueous solu-18 tions of the regenerated product and the starting material 19 and adjusting the pH of the solutions to 6.7 with a dilute sodium hydroxide solution. The viscosities of the two 21 solutions were measured with a Can~on Fenske Viscometer at 22 25C. The viscosity of the regenerated hemicellulose was 23 observed to be 138.5 sec. and the starting material 146.2 sec.
24 -~
To identify the product as the nitrite ester and 26 to determine the D.S., an excess of triethylamine was added 27 to the reaction mixture and the slightly alkaline solution 28 was poured slowly and with stirring into ice water which 29 resulted in the separation of hemicellulose nitrite ester.
The hemicellulose nitrite was removed, suspended in water, ' 3 ~05~880 1 and the mixture acidified with sulfuric acid and atirred 2 ~or about 1 hour. Then it was neutralized with sodium 3 hydroxide and the neutral solution was added to 4 volumes 4 of methanol, wherein hemicellulose separated, and was remo~ed, washed with methanol, dried and weighed.

7 The filtrate was collected, the methanol removed ~ by concentration in vacuo, and the resulting aqueous nitrite 9 solution was oxidized with a permanganate solution to form nitric acid, the presence of which was established by its 11 determination as nitron nitrate accordin~ to the method of 12 Hick described in Analyst, supra.

14 ~he degree of substitution was calculated by the weight of the hemicellulose and the amount of nitrous acid, 16 and was found to be about 2Ø With less N20i, the D S. w~s 17 correspondingly lower.

19 Results substantially similar to those obtained abo~e are obtained when the following re2gents are substi-21 tuted for N,N-dimethylformamide: N,N-dimethyl acetamide, 22 pyridine, ~uinoline and mixtures thereof, and mixtures of 23 one or more of the above sol~ents and benzene, ethyl acetate, 24 or acetone. Li~ewise, dinitrogentetroxide liquid or nitrosyl chloride can be substituted for the dinitrogentetroxide gas 26 to produce substantially similar results.

28 ~emicellulose nitrate ester is prepared from the 29 hemicellulose nitrite ester in the same manner as related in Section B of Example I.

32 ~ -~ 3~

:

1 Ex~MPLE III
2 A~ Preparation of Starch Nitrite Ester from Preqelatinized ~ Starch A 500 ml. ~hree-neck round bottom flask equipped 6 with a mechanical stirrer and calcium chloride tube was 7 charged with 40 g. of pregelatinized starch and suspended 8 in 300 ml. of DMF. Under exclusion of moisture, approxi-g mately 64 g. of dinitrogentetroxide gas was slowly introduced to the mixture at room temperature and the mixture was 11 mechanically stirred to form a clear viscous solution of 12 starch nitrite ester.

14 To test the resuLting solution, an excess of pyridine was added to a portion of the solution and the 16 slightly aiXaline mixture was slowly poured with stirring 17 into ice water to separate a fibrous precipitate. The 18 precipitate was removed, washed with ice water and pressed 19 out. The resulting precipitate was found soluble in the common polymer ester solvents described in Example IA. Upon 21 drying, the precipitate decomposed releasing brown fumes, 22 indicative of a nitrite. The dried precipitate was again 23 tested for its solubility, and found to be insoluble in the 24 common polymer ester solvents.

26 Another portion of the starch nitrite ester solu-27 tion was slowly added to four volumes of methanol with 28 agitation, and the precipitate was identified as starch by 29 IR spectrophotometry and by negative nitrogen analysis by the ~jeldahl method.

. 1051880 1 The lack of aepolymerization of the regenerated 2 starch was determined by preparing a 1% aqueous solution of 3 the regenerated product and comparing its viscosity against 4 the starting material. The solutions were adjusted to a p~
of 6.0 with a dilute sodium hydroxide solution and the vis-6 cosities of the two solutions were measured with a Cannon q Fenske Viscometer at 25 C. The viscosity of the regenerated 8 starch was observed to be 29.3 sec. as compared to 30.4 sec.
9 for the starting material.

11 ~he product was identified as starch nitrite ester 12 and its D,S, determined by the method described under Example 13 II for hemicèllulQse. The degree of substitution was calcu-14 lated by the weight of starch ~nd the amount of nitrous acid, and found to be about 2.8~ ~he D S, was lower if a lower 16 amount of dinitrogentetroxide was used for ni~rosation.

18 ~esults substantially similar to those o~tained 19 above are obtained when the following starting materials are substituted for the pregelatinized starch: alginic acid, 21 guar gum and locust bean gum or starch derivatives containing 22 free hydro~yl groups, such as hydroxyethyl starch. Likewise, 23 N,N-dimethyl acetamide, pyridine, quinoline and mixtures 24 thereof, and mixtures of one or more of the above solvents and benzene, ethyl acetate, or acetone may be substituted for 26 N,N-dimPthylformamide to obtain substantially the same results.
27 Further, nitrosyl chloride, liquid dinitrogentetroxide, or a 28 solution of dinitrogentetroxide in one of the above solvents 29 could be substituted for the dinitro~entetroxide gas and 3G produce substantially similar results.

_~ _ 1~51880 1 Tbe starch and other polysaccharide ester solution 2 was converted to the corxesponding nitrate ester solution in 3 a manner similar to Example IB.
, EXAMPL~ IV
~ ~. PreParation of PolYvinvl Nitrite_Ester from PolYvin 7 - Alcohol 9 To n dry 500 ml. three-neck round bottom flask, 10 g. of finely ground polyvinyl alcohol having a degree of 11 saponification greater than 9~/O was suspended in 100 ml. of 12 ~,N-dimethylformamideO The mixture was mechanically stirred 13 and under exclusi~n of moisture, d~nitrogentetroxide gas was 14 introduced. The vessel was cooled with cold water to keep the temperature at approximately 25~C. A clear viscous 16 solution was obtained upon the addition of approximately 20 g.
17 of dinitrogentetroxide gas.

19 Upon analysis, according to the methods described in Examples II and III, the resulting product was identified 21 as polyvinyl nitrite ester having a degree of substitution 22 of 0.8.

24 It was found that when the polyvinyl alcohol starting material had a degree of saponification less than 26 9~/O for example a product containing about 5~/O acetyl groups 27 and 5~/O free hydroxyl groups, substantially the same results 28 could be produced as obtained above, however the amount of 29 dinitrogentetroxide gas required to solubilize the starting material was less.

1 The nitrite ester wa~ converted to the nitrate 2 ester in a manner similar to Exampl~ IB.
4 BX~MPL~ V
~ Ao Preparation of Sodium Alqinic Acid Nitrate Ester 7 2 g. of alginic acid was suspended in 80 ml. of 8 ~F and solubilized by 4~5 g. of dinitrogentetroxide gas 9 according to the procedure of Example III, The solution was heated at 90 for 40 minutes and added slowly, with 11 agitation, to 3 volumes ethanol to precipitate alginic acid 12 nitrate ester. The isolated precipitate was resuspended in 13 water and ne~trali~ed with sodium hydroxide. The neutralized 14 solution was then added slowly to 3 volumes of ethanol to precipitate sodium alginate nitrate ester 16 ~
17 ~-e~ults substantially similar to those obtained 18 above are obtained when pectic acid is substituted for 19 algini acid. The substitution of potassium hydroxide, calcium hydroxide, magnesium hydroxide and a~monium hydrox-21 ide for the sodium hydroxide results in the corresponding 22 potassium, calcium, magnesium and ammonium salts of the 23 polyuronic nitrate esters.

EXAMPLE VI
26 A. Preparati~n of Cellulose Sulfuric Acid Ester 28 10 g. of cotton linter pulp having a high degree 29 of polymerization was suspended in 500 ml. of D~ and reacted with dinitrogentetroxide to form the nitrite ester thereof f~ 39 ~, `, ~_ 1{)518~0 with the maximum D.~. in accordance with Example IA. 40 ml.
2 of DMF containing 3.5 g. of sulfur trioxide was added to the 3 nitrite ester mixture dropwise over a period of about 40 4 mi~utes maintaining the temperature of the solution at 15C., ~ with vigorous agitation to form a viscous solution. 20 ml.
6 of water was added to the viscous solution and it was then 7 poured slowly and with vigorous agitation into 3 volumes of 8 acetone to precipitate cellulose sulfuric acid ester, which g precipitate was kneaded, washed and acetone, and redissolved in ice water, 12 B. Preparation of Sodium Cellulose Sulfate Ester 14 The solution prepared in accordance with Example VIA was neutralized by the addition of sodium hydroxide to 16 a p~ of about 8.0 to form a viscous solution of sodium 17 cellulose sulfa~e ester. The solution was added slowly and 18 with agitation to 3 volumes of acetone to precipitate and 19 isolate the product. The precipitated product was kneaded, collected, washed with fresh acetone and dried. Upon analysis, 21 the yield of sodium cellulose suLfate ester was 13.9 g. having 22 a degree of substitution of 0.65, and a viscosity of 6500 cps.
23 as a 1% aqueous solution.

26 The viscosity was measured with a Brookfield 26 Viscometer, Model LVT, at 12 RPM and 25C. To determine 27 the degree of substitution, a 0.4 g. aliquot of the product 28 was dissolved in 2~o aqueous hydrochloric acid and heated 29 for 15 hours at 100C. A dark brown solution was formed and filtered. To th~ filtrate, an excess of barium acetate .. , l~S188~

1 was added to precipitate sulfuric acid as barium sulfate.
2 The barium sulfate was dried and weighed and the degree of 3 ~ubstitution calculated therefrom.

~ Results substantially similar to those obtained 6 above are obtained when the cotton linter pulp starting 7 material is replaced by cellulose from other sources and/or 8 having a lower degree of polymerization, hemicellulose, gum 9 arabic, starch, alginic acid, guar gum, locust bean gum and polyvinyl alcohol. Other solvents capable of forming a 11 complex with sulfur trioxide and which may be substituted 12 for DMF in the DMF-sulfur trioxide complex are N,N-dimethyl 13 acetamide, pyridi~e, trialkylamine, dimethylsulfoxide and - 14 dioxane. Likewise, the sulfur trioxide may be added to the solution~in the form of a liquid or a gas, or diluted with 16 an inert solvent such as carbontetrachloride though the 17 reacti~n-is ~sghly exothermic and the use of an ice bath is 18 necessary.

I When the above procedure was repeated and the 21 amount of sulur trioxide was reduced to 2.5 g., the result-22 ing product had a degree of substitution of about 0.5 and a 23 viscosity of about 6000 cps. The yield ~as reduced only 24 slightly to 13.4 g.

26 An increase of the sulfur trioxide to about 4-5 g.
27 and about 6-7 g. resulted in D,S,'s of about 0.7-0.9 and 28 about 1.0-1.1 with viscosities of about 6000-8000 cps. and 29 about 3000-4000 cps., respectively. However, a further increase of the sulfur trioxide did not result in D S, values 31 of much above 1.0-1.1 under these conditions.

32 r C.,! ,L/
~ ~6 ~

lOS1880 1 Simi~ar results were obtained when cellulose 2 nitrite ester with a D.S. of 2~4-2 5 was used.

4 D,So ~Degree of sulfation) values of 1.2-1.3 and about 1.5-1~6 were obtained by using a cellulose nitrite 6 ester having a D.S. of about 1.7-2.0 and about 1.4-1.6 and 7 increasing the amount of sulfur trioxide to about 8-10 g.
8 and 12-14 g., respectively. The viscosities of 1% a~ueous 9 solutions of the products were about 1500-2000 cps. and about 800-1500 cps., respectively Similar results were 11 obtained with starch, guar and locust bean gums, and with 12 hemicellulose. Also, methyl cellulose with a D S. of about 13 1.0-1.5, carboxymethyl cellulose, hydroxy ethyl starch, 14 acetylated alginic and pectic acids (with a degree of acety-lation of below about 1.5) and hydroxypropyl guar were found 16 equally suitable for nitrosation and subsequent sulfation.
17 Rowever, the amount o~ re~gent necessary for full nitrosa-18 tion was based only on the number of free hydroxyl groups.

When cotton linter cellulose with a lower degree 21 of polymerization was used, the D.S.'s were similar but the 22 viscosities were correspondingly lower. Similarly, cellulose 23 from other sources generally produced products with lower 24 viscosities.

26 FX~MPL~ VII

28 Cellulose (25 g.) was suspended in 1000 ml. DMF
29 and about 38 g. N2O4 were introduced to obtain cellulose nitrite ester. A solution of a calculated amount of DMF-S03 32 f-~,~ , f;tc~

1 complex ~n DM~' was then slowly adcled with stirring and 2 cooling to result in a degree of ~ulfation of about 0.8.

4 At this stage, a small portion of the mixture was removed, and, after removal of the nitrite groups and neu-6 tralization, the product was dialyzed, isolated, and analyzed 7 The D.S. was found to be 0.8.

9 - The main portion was mixed with the stoichiometric amount of methanol req~ired for the quantitative removal of 11 the nitrite groups, and subse~uently another portion of DME-12 S03 complex, which theoretically was sufficient to increase 13 the D.S. to about 2.0, was added over a period of 2 hours.
14 After a total reaction period of about 3 hours, the mixture was neutralized and the product isolated as described above, 16 dialyzed, and its D.S. determined. The D.S calculated was 17 ~.8 indicating that no further substitution had occurred 18 after removal of the nitrite groups.

Similar results were obtained with guar and locust 21 bean gums. This illustrates that sulfation under these con-22 ditions does not occur without the prior nitrosation step of 23 this invention.

EXAMPLE VIII

27 To test the compatibility of the various sodium 28 cellulose sulfate esters of this invention with metal ions, 29 1% aqueous solutions of the esters were mixed with the same volume of a 2~/o salt solution. In cases ~here 2~/o was above 31 saturation, a saturated salt solution was used.

. .. -, -- ~_ 1 Products at all D.S levels were compatible, i.e., 2 no precipitation or gelling occurred, with ammonium sulfate, 3 sodium chloride, potassium chloride, magnesium chloride, 4 calcium chloride, calcium hydroxide, strontium chloride, strontium hydroxide, aluminum sulfate, sodium aluminate, 6 zinc sulfate, sodium zincate, nickelous sulfate, cobaltous 7 sulfate, cupric sulfate, cadmium chloride, ferrous sulfate, 8 chromic chloride, lead acetate, mercuric acetate, silver 9 nitrate, stannous chloride, and sodium stannite.
11 As a simple test for determining compatability with 12 metal ions, a ~/~ solution of the cellulose sulfate in an aqueous 13 medium may be~ admixed with a ~/O potassium chloride solution on 14 an equal volume basis after heating of both solutions to a temperature of about 80C. After mixing, the mixture may be 16 allowed to cool. The compatability of the cellulose sulfate 17 wi~h potassium i-ons i8 shown by the absence of a precipitate 18 and the absence of gelation.

Sodium cellulose sulfate esters with a D.S. of 21 about 1.3 and lower were compatible also with barium acetate, 22 barium hydroxide, cerous chloride, and ferric chloride.

24 In most cases, the solutions could be saturated with the salt without causing precipitation or gelation.

EX~MPLE IX
2 A. hickened Rubbinq Alcohol Composition 4 A thickened rubbing alcohol having the following

5 composition is prepared:

6 Component % by Weiqht

7 Cellulose Nitrate Ester ~,0

8 Water 25.0

9 ~thyl Alcohol 70;0 11 The thickened rubbing alcohol exhibits a desired 12 increased viscosity which tends to slow down evaporation of 13 the alcoholic solution, prolong skin contact and thereby aid 14 absorption, :
16 . EX~MPL~ X
1~ A. N~n-~unninq Glue 19 Component Amount by Weiqht 20 Bone Glue 150.0 g.
21 Sodium cellulose sulfate 5 g, 22 Water . 1000 g.

24 This improved glue exhibits a higher ~iscosity tenaing to retard running of the glue, particularly on 26 vertical surfaces. The particular composition exhibited 27 a viscosity of 1000 cps. at 25C. and about 300 cps. at 50C.
28 and did not interfere with or change the properties of the 29 bonding glue.

~,,, ~5 _ .~ _ 10518~30 1 Among the other utilities for my cellulose ~ulfate 2 products are their application in oil well drilling mud as a 3 suspending agent, in secondary oil recovery through water 4 flooding as a thickener of the water phase, in cosmetics as an emulsifier and emollient, in food products as a thickener and 6 stabilizer, in cleaning compositions as a stabilizer and 7 thickener, in wax emulsions, paints, and photographic emulsion 8 e.g., for protein reactivity, etc.

EXAMPLE XI

12 Utilizing the process of the invention as described 13 above, esters` of polyhydroxy polymers such as polysaccharides, 14 polyvinyl alcohols, and partially substituted etherified or esterified polysaccharides and polyvinyl alcohols which still 16 contain a substantial number of free hydroxyl groups are pre-17 pared and the following specific products are obtained thereby:
18 A. Nitrite esters of polysaccharides, polyvinyl 19 alcohols, polysaccharides partially substituted with stable radicals, and polyvinyl alcohols partially substituted with 21 stable radicals.
22 B. Nitrite esters of starch, guar gum, locust bean 23 gum, hemicellulose, gum arabic, mannan, alginic acid and pectic 24 acid having a D.S. between 0.1 and the maximum.
C. Nitrite ester of cellulose having a ~.S. between 26 about 0.1 and 2Ø
27 D. Nitrite ester of cellulose having a D.S. between 28 2.0 and 3Ø
29 E. Water soluble nitrate esters of polysaccharides and polyvinyl alcohols having a D.S. of less than 1Ø

~ ~ .

. ~OS188~
1 F. Sulfuric acid esters of polysacchariaes and 2 polyvinyl alcohols and salts the~eof with a D.S. of below 3 2.0 and with substantially uniform distri~ution of sulfate 4 groups over the macromolecule.
G. Sulfuric acid esters of guar gum and locust 6 bean gum having a D,S. of between 1.0 and 2Ø
7 H. Sulfuric acid esters of cellulose having a 8 D.S. of ~etween 1.0 and 2Ø
9 I. Water soluble sulfuric acid esters of cellulose having a D.S. between 0.3 and 1Ø
11 J. Sulfuric acid esters of cellulose having a 12 D.S. between 1.0 and 1.3 the aqueous solutions of which are 13 compatible and non,gellable in the presence of potassium, 14 barium, strontium, cerous, aluminum, and ferric ions.
~. Sulfuric acid esters of cellulose having a D.S.
16 of less than 2.0 and with su~stantially uniform distri~ution 17 of sulfate groups over the macromolecule, the,aqueous solutions 18 of which are compatible and non-gellable in the presence of 19 potassium, strontium and aluminum ions.
21 As stated previously, a further aspect of the 22 invention involves the use of an activated cellulose polymer 23 in the formation of a nitrite ester. This aspect of the 24 invention is illustrated in the follo~ling Examples in which all parts and percentages are by weight unless otherwise 26 indicated.

.~
, ... .

~05~80 1 EXAMPL~ XII

3 Cotton linter pulp was dried at 100 to 110C. in 4 vacuo over P205 for 5 hours; a dried 20 g. portion was placed in a three-neck round bottom flask provided with a 6 calcium chloride tube, a strong stirrer, and a dropping 7 funnel, and 1 liter of DMF was added. An amount of 30 g. of 8 N2O4 then was introduced with stirring over a period of 9 about 30 minutes while the temperature of the mixture was kept below about 30C. by cooling in a cold water bath. The 11 mixture thickened, but the reaction was incomplete even 12 after mixing for several hours indicated by the presence of 13 haze and apparentLy unreacted fibers. The addition of 14 another 3 g. of N204 did not result in a substantial improve-ment.

17 In isolatlng and analyzing the resulting cellulose 18 nitrite ester, to a small portion of the mixture was added an 19 excess of pyridine. The slightly alkaline mixture was added to ice water, ~he precipitate collected, wash~d with ice 21 water, and pressed out while the tçmperature was kept at 22 about 0C. The material was redispersed in distilled water 23 in a closed Erlenmeyer flask and acidified with sulfuric acid.
24 After stirring magnetically for about 1 hour, the mixture was neutralized and the regenerated cellulose removed, washed, 26 dried, and weighed. The filtrate was collected quantitatively 27 and the nitrite determined by oxidation with permanganate to 28 nitric acid. The presence of nitric acid su~sequent to 29 oxidation was established by its determination as nitron nitrate according to the method of Hick described in Analyst, ~:.

:
105~880 l Vol. 59, page 18 - 25 (1934). The degree of nitrosation 2 was found to be about 2.7-Z.8.

4 The cellulose nitrite reaction mLXture prepared from 20 g. of cellulose and 30 g. N204 was sulfated by the 6 slow addition (about 30 min.) of a solution of DMF-S03 7 complex (about 6 g. S03) in DMF. The reaction was carried 8 out with strong stirring and under exclusion of moisture, 9 and the temperature was kept below about 20C. The mixture remained hazy and still contained fibers even after mixing ll for about 1-2 hours. The reaction mixture was then trans-12 ferred to a mixer, diluted with about 500 ml. of water, and 13 adjusted to a pH of 7-8 by the slow addition of sodium 14 carbonate solution. During neutralization, the temperature of the mixture was kept below 20-25C by the addition of 16 ice. Enough isopropanol was then added to separate the 17 pIoduct, and the product was pressed out, washed twice with 18 aqueous isopropanol, pressed out again, dried in vacuo at l9 lOO~C, and milled. The product had a D,S, of about 0.6 and a 1% aqueous solution a viscosity of about 3000 cps. (Brook-21 field Viscometer, LVT Model, 60 RPM) but was somewhat hazy 22 and contained fibers.

24 In another experiment, 20 g. of anhydrous cotton linter pulp was treated as described above, but only about 26 15 g. of N204 was used for the nitrosation to result in a 27 D,S. of about 1.5 and an amount of Dr~F-so3 complex contain-28 ing about 12 g. of S03 for the subsequent sulfation. The 29 results were similar to those above. The cellulose sulfate had a D S, of about 1.5, and a 1% aqueous solution had a 31 viscosity of about 500 cps. but was hazy and contained fibers.

~q - . . _~ _ lOS~880 1 Esser~tially similar results were obtained when 2 wood cellulose, cellulose from vegetable hulls or bagasse, S and chemically treated and degraded cellulose, such as 4 Whatman Cellulose Powder were substituted for the cotton linter pulp. However, it appeared that the reaction with 6 Whatman Cellulose Powder proceeded more smoothly and that a 7 solution of its final sulfated product was the least hazy and contained a lesser amount of fibers than those produced 9 from other cellulose types.

11 Substitution of the DMF in the reaction medium by 12 DMAC or pyridine or mixtures of these compounds did not 13 essentially chang~ these results. Also, no essential dif-14 ferences were noticed when the S03 was used as a complex wit~ other solvents, such as DMAC, dioxane, DMSO, and the 16 like, or when NOCl was used instead of N204 provided, how-17 ever, t~at the molar amount of NOCl was increased 2.5 to 3 18 fold.

2Q EX~MPLE XIII

22 Cotton linter pulp as described in Example XII
23 was suspended in water and mixed in a Waring Blender for 24 2 min., pressed out, washed with DMF, and pressed out again.
The cellulose then had a water content of about 8-1~/o~ A
26 portion of 20 g. of this cellulose then was nitrosated with 27 30 g. of N204 as described above. The resulting solution 28 was clear and did not contain fibers after a reaction time 29 of 20-30 min., and no excess of N204 was required to obtain a quantitative reaction. The sulfation was carried out as o ~, I _,~_ . 1051~3~0 1 des~ribed above and resulted in products forming perfectly 2 clear solutions that did not contain fibers.

4 Similar results were obtained when the residual water content was 5% and ~h or when cotton cellulose was 6 replaced by wood cellulose or celluiose from bagasse or 7 chemically treated cellulose.

9 When the amount of DMF-SO3 complex added was that calculated to produce a D S. of below about 0.3-0.4, the 11 resulting product was insoluble but highly swellable in water.

13 ` . ~XAMPLE XIV

Cotton linter pulp was hydrated by treatment with 16 - water in a Waring Blender as described above. The cellulose 17 then was pressed out and divided into 4 portions. One portion 18 was dried in vacuo at 30-40C with continuous mixing down to 19 a water content of about 2~/o The other three parts were dried under the same conditions to 8-l~o~ 4~5%~ and l-~/o water, 21 respectively. For the last sample the temperature was somewhat 22 increased. Amounts of 20 g. of each of the parts were nitro-23 sated as described above with 30 g. of N2O4. The reactions 24 with samples containing 8-l~o and 4~5% moisture proceeded smoothly and were complete after about 20-30 minutes forming 26 clear, viscous solutions. The cellulose containing 2~o mois-27 ture required about 35 g. N2O4 and formed a clear solution 28 soon after the 5 g. excess had been added. The cellulose 29 portion containing l-~o moisture required a long time of mixing and, even after the addition of a modexate excess, 31 remained somewhat hazy and contained fibers.

- ~0518~0 ~ Subsequent sulfations using DMF-S03 complex con-2 taining about 6 g. of S03 in each case resulted in cellulose 3 sulfates with a D.S. of about 0.6 producing sparkling clear 4 solutions in water when celluloses with moisture contents of 5 2~/o~ 8~ o~ and 4-5% were used initially Solutions of the 6 reaction product from cellulose with the lowest mo;sture 7 content, however, were somewhat hazy and appeared to contain fibers.

Similar results were obtained when cotton linter 11 pulp was replaced by wood cellulose or cellulose from 12 vegetable hulls or bagasse, or when the DMF was substituted 13 by DL~C, or when instead of the DÇ~F-S03 complex, a complex 14 with dioxane, DMAC, D~O, or the like was used.

16 In another identical experimental series, where 17 20 g. portions of cellulose were nitrosated with about 20 g.
18 of N204 (about 25 g. of N2O4 required for the cellulose con-19 taining about 2~/o moisture) and sulfated with DMF-S03 complex containing about 10-12 g. of SO3, products with D.S. values 21 of 1.1-1.2 were obtained, but otherwise results were similar.

23 ~he nitrosation and subsequent sulfation proceeded 24 similarly smooth and resulted in sulfated products forming clear aqueous solutions when a commercial cotton linter pulp 26 or wood cellulose with moisture contents of between about 27 4-12% was used directly. If 5%, l~/o~ or 2G% water was added 28 to anhydrous cellulose at once just before the reaction, 29 results were similar to those obtained under Example XII
with anhydrous cellulose.

i _ ~ _ lOS18~BO
1 BX~MpL~ XV

3 Five samples of cotton linter pulp (20 g. each) 4 were nitrosated as described above with about 30 g. of N204 each and then sulfated with DMF-S03 complex contain-6 ing the theoretical amounts of S03 calculated for ~.S.
q values of about 0.4, 0.6, 0.8, l.lo and 1.6. After 8 neutralization and isolation, the D.S. values o~ the g products were found to be about 0.4, 0.6, 0.8, 1.1, and 1.1, respectively. The same D,S, values of about 1.0-1.1 11 were obtained also when the amount of N204 was reduced to 12 25 g. or about 20 g. and the S03 was calculated for a D.S.
13 of about l.l~and 1.6.

Cotton linter pulp (20 g.) which wa~ nitrosated 16 with 14 to l5 ~. of N204 produced, after sulfation with a 17 -t~ecr~ti~al-amount-or a moderate excess of S03, a product 18 with a D.S. of about 1.5 to 1.6. If the N204 was increased 19 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 nitro-21 sation about 25 g. of N204 was used, theoretical amounts of 22 S03 were sufficient to produce D,S values of between about 23 0.5 and 1.1. ~f less than about 10 g. of N204 was used for 24 nitrosation, no complete sulfation was attained with D~lF-S03 complex even when used in moaerate excess. Substantially 26 similar results were obtained when, instead of cotton linter 27 pulp, wood cellulose or bagasse was used.

2g S~

`

10~880 I.
I
1 EX~MPLE XVa 3 Carboxymethyl cellulose (10 g.) with a D.S. of about 4 1.O was suspended in about 500 ml. DMF, and 7.5 ~o 8.0 g. N204 was introduced under exclusion of moisture and with strong 6 agitation. The mixture formed a light green, viscous solution 7 of carboxymethyl cellulose dinitrite ester.
& -.
9 For the isolation and identification of the ester, the same procedure was used as described under Example 1 for cellulose

11 nitrite ester. If less N204 was used for the nitrosation, the

12 degree of nitrosation was correspondingly lower.

13

14 Similar results were obtained when methyl cellulose with a D.S. of 1.O and 1.5, hydroxypropyl cellulose with a D.S.
16 of 0.8, a-cetyl alginic acid esters with a D.S: of 0.5 and 0.8, 17 hydroxyethyl starch with a D.S. of about 0.2, partially hydrolysed 18 polyvinyl acetate with a D.S. of 0.4, acetyl pectic acid ester 19 with a D.S. of 1.2, hydroxyethyl guar and locust bean gums with a D.S, of about 0.4 and 0.7, hemicellulose nitrate ester with a 21 D.S. of about 0.3 (as described in the German Offenlegungsschrift 22 No. 2,120,964), polyvinyl alcohol sulfuric acid ester with a D S.
23 of 0.3, starch phosphate~ carrageenan (free acid3, xanthan gum 24 (free acid), or gum karaya were nitrosated under similar condi-tions with stoichiometric amounts of N204 to result in complete 26 or partial esterification of the free hydroxyl groups.

28 Similar results were obtained when the D~ was replaced 29 by DMAC, pyridine, isoquinoline, quinoline, and the like, or when NOCl instead of N204 was used provided that its molar amount was 32 ~r~ 5 ~ -~ J
~, , 10518~30 1 essentially tripled. Also, the reaction medium could contain 2 substantial quantities of an inert ~olvent, such as ethyl 3 acetate, ethyl formate, benzene, toluene, ethylene dichloride, 4 acetone, methylethyl ketone, and the like, without substantially ~ changing the reaction~

9 DMF (100 ml) was poured into a 250 ml two-neck round bottom flasX equipped with calcium chloride tube and 11 magnetic stirrer. Then, 23 g. of N2O4 (1/4 mole) was added 12 with stirring and cooling which resulted in the formation 13 of a deep green solution. To this solution, 12 g. absolute 14 ethyl alcohol (about 1/4 mole) was added solwly with stir-ring. During addition of the last ml, the solution became 16 light yellow indicating com~lete consumption of the N204.
17 Then, the solution was neutralized by the addition of 18 pyridine and subjected to fractionated distillation. The 19 first fraction was collected in a flask cooled with acetone -dry ice and consisted of about 18 g. of a yellowish liquid 21 having a boiling point of 17-18C: No ethyl alcohol was 22 recovered during distillation.

24 Using the same conditions as in Example XVI, the ethyl alcohol was replaced by propanol, isopropanol, butanol, 26 isobutanol, tertiary butyl alcohol, amyl alcohol, isoamyl 27 alcohol, and hexyl alcohol and 1/8 mole ethylene glycol. On 28 fractionated distillation, the corresponding nitrite esters 29 were recovered in 80-9~/o yields with boiling points of about 3C 57C., 45C., 77C., 68C., 63C., 104C., 99C., 130C., and 31 98C., respcctively. In no case was any alcohol recovered.

~, -- ~r _ , _ 1 In another scries of experiments, 15 g. of a low 2 D.P. cellulose was suspended in the 100 ml of DMF before 3 the N204 was added. Addition of 23 g. of N204 with strong 4 stirring resulted in a cellulose trinitrite ester solution.
To this solution, alcohol under conditions and in amounts 6 as described above (1 mole alcohol or 0.5 mole diol per 7 mole N204) was added. Free cellulose separated and was 8 removed. The filtrate was neutralized and distilled as 9 described above and the corresponding alkyl nitrites were obtained in yields of 80-85% of the theory. Similar 11 results were obtained when, instead of cellulose, stoichio-12 metric amounts of methyl cellulose, starch, alginic acid, 13 or polyvinyl alcohol were used.

In a third experimental series, to cellulose 16 trinitrite ester solutions obtained under conditions and 17 i~ amounts as described above were added slowly and with 18 continuous stirring amounts of D,~F-S03 complex to result lg in mixed cellulose nitrite sulfuric acid esters having degrees of sulfation of about 0.4, 0.8, and 1.1. To these 21 ester soiutions~ alcohol was added under conditions and in 22 amounts as described above, the cellulose sulfuric acid 23 ester precipitated by the addition of a sufficient amount 24 of acetone and removed, and the filtrate neutralized with pyridine and subjected to fractionated distillation. The 26 corresponding alkyl nitrites were recovered in a purity and 27 in yields similar to those obtained from cellulose trinitrite 28 ester solutions above.

10518~0 3 Cotton lint~r pulp (400 g.) having a moisture 4 content of about 5-6% was mixed with 2 1. of DMF in a double ~ planetary mixer with cooling and under exclusion of moisture, 6 and 600 g. of N2O4 was added over a period of about 30 minuteS
7 to result in a cellulose trinitrite ester. Then, a DMF-S03 8 slurry in DMF containing about 200 g. of S03 was added 9 slowly over a period of about 30 minutes and mixing continued for another 10-15 minutes. An amount of 485 g. of isobutyl 11 alcohol was added slowly, and the mixture was neutralized 12 (pH 7-8) by the addition of an aqueous solution of sodium 13 carbonate or ~a slurry of sodium carbonate in a saturated 14 solution or by the addition of dry sodium carbonate. Good and thorough mixing was required for this neutralization -16 step, and generally the presence of water produced better 17 results. The temperature of the reaction mixture was main-18 tained below about 20C. throughout the reaction until 19 neutralization was complete, and up to the neutralization step, the reaction was carried out under exclusion of 21 moisture. The neutral mixture was then pressed out or 22 centrifuged, and if the solids were too soft to be pressed 23 out, some isopropanol was added to harden them sufficiently.
24 The solids were suspended in about 60-7~o aqueous isopropanol, pressed out again, dried, ana milled. For higher purity, 26 the solids were suspended in aqueous isopropanol a second 27 and, if necessary,- a third time before final drying and milling.

29 The filtrates were combined and subjected to fractionated distillation for solvent recovery. One of the .
~ 5~
_,~ _ 105~380 I
1 fractions distilled at about 66-67~C. and was identified as 2 isobutyl nitrite, the yield being over 8~o~ ~he brown, 3 crystalline residue from distillation contained the theo-4 retical amount of sodium nitrite. An aliquot of it was purified by recrystallization.

7 In other identical experiments, the isobutyl 8 alcohol was replaced by n-propanol, amyl alcohol, and - 9 ethylene glycol. Instead of isobutyl nitrite, the corre-sponding nitrite esters of n-propanol, amyl alcohol, or 11 ethylene glycol were recovered, but otherwise results were 12 similar. In another similar experiment where the isobutanol 13 was replaced ~y an equivalent amount of water, similar 14 results were obtained, but the residue from the solvent recovery contained equivalent amounts of sodium nitrite and 16 sodium nitrate in theoretical yields. Part of the residue 17 was recrystallized to result in a purified salt mixture.

; 19 The sodium cellulose sulfate had a D.S, of 1.0-20 1.1, and a 1% aqueous solution had a viscosity of 1500-2000 cps.

22 In another experimental series, products were 23 obtained under similar conditions, but the amount of SO3 24 used for the sulfation was reduced to obtain products with D.S. values of about 0.4, 0.6, and 0.9. These D.S. values 26 were attained with the theoretically calculated amounts of 27 SO3, and 1% aqueous solutions of the products had viscosi--28 ties ranging between about 5000 and 2000 cps. In another 29 experiment, tbe amount of N2O4 was reduced to about 300 g.
and that of S03 increased to about 300 g. to result in 32 , ~05181~0 1 sodium cellulose sulfate esters with a D.S. of 1.5-1.6 2 having 1% aqueous viscosities of about 600-700 cps.

4 Other cellulose materials, such as wood cellulose or cellulose from vegetable hulls were used with equal 6 success, but the final products had a somewhat lower solution 7 viscosity than those from high D.P. cotton linter pulp.
8 Also, neutralization could be carried out equally well 9 with carbona.tes, bicarbonates, and hydroxides of the other alkali metals, such as lithium and potassium, of 11 alkali earth metals, such as magnesium and calcium, and of 12 manganese, cobalt, and nickel and with ammonium hydroxide 13 and amines. In the case of the alkali metals, carbonates 14 and bicarbonates are preferred to the hydroxides because of the high alkalinity of the hydroxides and the danger of 16 degradation 18 Also an integral part of my invention is the process 19 of making films, fibers, and other shaped articles by (1) preparing a solution or paste containing the labile.nitrite ester 21 of one or more polyhydroxypolymers or a solution or paste of 22 both one or more polyhydroxypolymer nitrite esters and one or 23 more polymers lacking hydroxyl groups and (2j contacting said 24 solution or paste with a protic solvent in the presence of an acidic catalyst to cause (a) regeneration of the polyhydroxy-26 polymer and, essentially simultaneously, (b~ separation of both 2~ the regenerated polyhydroxypolymers and the polymers lacking 28 hydroxyl groups in such a manner that films, fibers, or other 29 shaped articles are obtained.
..

31 5q 32 . -~r-105~880 1 The first step o the process consists of making the 2 nitrite ester of the polyhydroxypolymer or polyhydroxypolymer 3 mixtures as previously described. As the polyhydroxy compound, 4 any polymer containing a substantial number of hydroxyl groups is suitable. This includes polysaccharides typified by 6 cellulose irrespective of its source, alginic acid, pectic acid, 7 pectin, hemicellulose, gum arabic, guar gum, locust bean gum, 8 gum karaya, and the like, polysaccharide derivatives still con-9 taining a substantial number of hydroxyl groups as typified by carrageenan and other polysaccharide sulfates, methylcellulose, 11 carboxyalkylcellulose, hydroxyalkylcellulose, hydroxyalkylguar 12 and other polysaccharide ethers, partially acetylated or 13 generally esterified polysaccharides, partially nitrated or 14 sulfated polysaccharides such as described previously, and the like, and synthetic polyhydroxypolymers typified by polyvinyl-16 alcohols with various aegrees of saponification and copolymers 17 containing vinylalcohol.

19 To the suspension of the polyhydroxypolymer(s) in one of the specified solvents or solvent mixtures, enough dinitrogen-21 tetroxide and/or nitrosylchloride is added in gaseous or liquid 22 form or as a solution preferably in one of the previously men-23 tioned solvents to obtain a highly esterified nitrite ester of 24 the polyhydroxypolymer(s). The reaction temperature should be maintained below about 50C. and preferably below about 30C.
26 If the temperature increases to above about 60C. over an extended 27 period of time, some nitration of the polyhydroxypolymer may occur.
28 This, however, may not have any disadvantageous consequences in 29 the subse¢uent film or fiber formation, and, in some instances, it may be even desirable.

~.,...i ~ ~d 1 Films, fibers, and other shaped articles of the 2 unmodified polyhydroxypolymer(s) are obtained by bringing the 3 paste or solution of the nitrite ester(s) into the desired shape 4 and then contacting it in the presence of an acidic catalyst with a protic solvent in which the resulting polyhydroxypolymer(s) 6 is (are) insoluble. Films, for example, can be made by spreading 7 the solution on a glass plate and treating it with a protic 8 solvent while fibers are obtainable by extruding the solution 9 into the protic solvent. The shaped objects then may be immersed in and washed with more solvent and dried. To 11 neutralize residual catalyst, a small amount of a base, such 12 as alkali or ammonium hydroxides or an amine, may be added to 13 one of the washes if so desired.

Although it is possible to first isolate the polymeric 16 nitrite ester and then redissolve it for the purpose of film 17 and fiber formation, it is preferred to use the reaction solution 18 containing the nitrite ester directly. The preferred acidic 19 catalyst is a mineral acid, such as hydrochloric, sulfuric, nitric, phosphoric acids, and the like, however, relatively 21 strong organic acids are suitable also. If an N,N-dialkylacylamld~
22 had been used as the proton acceptor for nitrosation of the poly-23 hydroxypolymer, the nitric acid and/or hydrochloric acid formed 24 simultaneously as a by-product is sufficient to serve as a catalyst. However, if a wea~ tertiary amine had been used for 26 this purpose, enough catalyst should be added to make the mixture 27 acidic. The catalyst must be anhydrous to avoid removal of 2~ nitrite groups prior to the treatment with the protic solvent.
29 Of course, a sufficient amount of catalyst may be added to the protic solvent instead of to the nitrite ester solution, and 31 film or fiber formation is achieved with similar success. In ~05~80 1 the case of a nitrite ester solution where a N~N-dialkylacylamide 2 i8 used as the proton acceptor, it may ~e advantageous to 3 neutralize or slightly alkalize the solution to eliminate the 4 reactivity to moisture and add the catalyst to the protic solvent.
S The protic solvent to be used depends largely on the polyhydroxy-6 polymer to be regenerated. For most polysaccharides and synthetic 7 polyhydroxypolymers, anhydrous or aqueous alcohols, such as 8 methanol, ethanol, isopropanol, and the like, are reguired g because of the water solu~ility of these polymers. In the case of cellulose or a mixture of a substantial amount of cellulose 11 and another polyhydroxypolymer, water may be used as well. At 12 ~imes, it is advantageous, i.e., the polymer separation is 13 improved, ~f~the protic solvent is mixed with another type of 14 solvent provided that this second solvent does not inactivate the cat~lyst and that it is completely miscible with the protic 16 solvent as well as with the nitrite ester solvent.
lq 18 In addition to the polyhydroxypolymer mitrite esters, 19 other solu~le polymers may be added to the nitrite ester solution.
This may be done by dissolving the polymer directly in the 21 reaction mixture containing the nitrite ester or by pre-dissolving 22 the polymer in a suitable solvent and adding the resulting 23 solution to the nitrite ester solution or vice versa. Although, 24 because of simplified solvent recovery, it is preferred to use the same solvent as contained in the nitrite ester reaction 26 mixture, other aprotic solvents, such as chlorinated hydrocarbons, 27 hydrocarbons, alkylesters, aromatics, acetonitrile, dioxane, and 2~ the like, may ~e used for pre-dissolving the polymer provided 29 that such solvent is compatible, i.e., completely miscible, with the nitrite ester reaction solution and with the protic solvent 31 to be contacted with subsequently. Of course, if the nitrite ~05~8~0 1 ester solution is neutral or alkaline, i.e., does not contain 2 the acidic catalyst, such solvent may also be protic as typified 3 by alcohol and water. In this case, the acidic catalyst is 4 added to the protic solvent to be used subsequently for the regeneration of the polyhydroxypolymer and the separation of 6 the polymer mixture in the form of certain shaped articles.
7 The type of additional polymer which may be added to the nitrite 8 ester solution may be any polymeric compound which either does 9 not contain any hydroxyl groups or the hydroxyl groups of which are essentially completely substituted. Polymers of that type 11 are synthetic polymers typified by polyacrylic esters, methacrylic 12 esters, polyacrylonitrile, and other acrylics, polyvinylesters, 13 -ethers, and ~halides, vinyl and acrylic copolymers, polystyrene 14 and copolymers, ethylene copolymers, propylene copolymers, phenolics, polyamides such as nylon, polyethers, polyesters, 16 polyalkyleneglycols, and others and highly substituted poly-17 saccharides typified by their nitrate, acetate, propionate, and 18 other esters, their methyl, ethyl, and other ethers, and the 19 like. The only requirements are that such polymer is soluble in one or more of the above solvents, that it is compatible with 21 the polymeric nitrite ester solution, and that it can be 22 separated simultaneously with the polyhydro~ypolymer by the 23 proper choice of the protic solvent or the solvent mixture con-24 taining the protic solvent. A limited amount of an additive, such as a plasticiser, or of a liquid lower molecular weight 26 polymer may be added also provided, of course, that it is 27 retained in the film or fiber and not leached out during film 2~ or fiber formation. Films, fibers, and other shaped objects are 29 obtained by contact with a protic solvPnt in the presence of an acidic catalyst in the way described above. As already mentioned, 31 the choicc of the protic solvent depcnds on thc polymer mixt~lre, ,~ . .

10518~0 1 and it should be selected in such a way that, on conta~t, re-2 generation of the polyhydroxypolymer and separation of both the 3 polyhydroxypolymer and the polymer lacking hydroxyl groups occur 4 essentially simultaneously. Of course, prior to contact with a protic solvent, part or most of the polymer solvent, especially 6 in the case of a low boiling solvent, may be evaporated and, 7 thus, the polymer concentration increased. This often improves 8 fiber and film formation.

The shaped articles obtainable by my process consist 11 of homogeneous and intimate mixtures of the polymers oriqinally 12 present in the polymeric nitrite ester solution. Thus, they may 13 consist of on~y one polyhydroxypolymer, or they may consist of 14 a combination of several polyhydroxypolymers or of one or more polyhydroxypolymers and one or more polymers lacking hydroxyl 16 groups. Of:~course, if desired, unreacted cellulose fibers may 17 be included in such articles by suspending the desired amount of 18 cellulose fiber in the polymer solution prior to film or fiber 19 formation, In combination of several polymers, the polymer ratio can be chosen arbitrarily, and the weight percentage of any 21 polymer may vary between about 0.1 and 99.9.

23 Shaped articles containing acidic polymers, such as 24 polymeric sulfuric or phosphoric acid esters, polyuronic acids, polyacrylic acid, and the li~e, may be modified further by 26 neutralizing with various bases, such as alkali, ammonium, and 27 alkali earth hydroxides and the various primary, secondary, and 28 tertiary amines Also, the alkali salt of such acidic compound 29 may be treated with a quaternary ammonium halide resulting in an exchange of the alkali ion by the quaternary ammonium ion. This 31 will produce property changes of the shaped obj~ct, such as I Ll ' r~

.

~0518~0 1 increased or reduced water sensitivity or even water repulsion 2 d~pending on the ion selected.

4 The usefulness of the shaped articles, particularly films and fibers, is obvious and need not be demonstratcd.
6 ~ilms of cellulose, cellulose acetate, and cellulose nitrate, 7 for example, are used in packaging material, membranes, and the 8 like, films of other polysaccharides are used as food packaging 9 materials, and fibers of cellulose, polyesters, polyamides, and other polymers are used in the manufacture of, for example, 11 textiles. The novel combination of several polymers as described 12 in this invention, such as cellulose - polyester, cellulose -13 polyvinylalcohol, polyvinylalcohol - nylon, and the like, in the 14 same film or fiber will combine some of the advantages of the iJ inaividual polymers but also will add new properties, such as 16 possibly higher strength, increased fiexibili~y, improved 17 dyability, antistatic properties, and the like. The incGrpora-lô tion of a negatively charged polymer in, for example, cellulose lg or cellulose acetate films may be useful in their application as osmotic membranes or, because of the added protein reactivity, 21 in the meat industry as, for example, sausage casing and in 22 medical applications.

24 The following examples illustrate spe~ific preferred embodiments of this invention and are not ir.tended to be limiting.

27 EXA~LE XVIII
2~
29 High molecular weight cotton linter pulp (10 g.) was suspcndcd in 300 ml. D~ and, under exclusion of moisture, 16 g.

105~80 1 dinitrogentetroxide was introduced slowly and with mechanical 2 agitation. Strong agitation was continued until a clear highly 3 viscous solution was obtained. Part of the solution was spread 4 evenly on a glass plate in a low humidity chamber and then sprayed with anhydrous or aqueous methanol, the film removed, 6 ~lotted between filter paper, immersed in and washed with 7 methanol, and dried. The film was clear and strong. Fibers of 8 high clarity and strength were obtained by extruding the solution 9 through fine nozzles into methanol, washing the resulting fibers with fresh methanol, and drying. If droplets of the solution 11 were dropped into methanol, washed with methanol, and dried, the 12 product was obtained in the form of granules. The granular size 13 depended on the concentration of the cellulose in the solution 14 and on the size of the droplets.
16 Similar results were obtained when a lower molecular 17 weight -cellulose or cellulose from other sources was used or 18 when the cellulose was replaced by polyvinyl alcohol, starch, 19 hemicellulose, guar gum, locust bean gum, alginic acid, pectic acid, hydroxyethyl cellulosè, methyl cellulose with a D.S. of 21 about 1.5, or propylene glycol alginate.

23 EX~MPLE XIX

Cotton linter pulp (5 g.) and 5 g. polyvinyl alcohol 26 were suspended in 200 ml. DMF, and sufficient dinitrogentetroxide 27 was introduced to result in a clear viscous solution on prolonged 2~ mixing. Films, fibers, and granules were obtained from this 29 solution as described under ~xample XVIII. Substitution of nitrosyl chloride for dinitrogentetroxide or of a mixture of 31 DMF and benzene for D~ produccd similar results.

1051~380 1 The same results were obtained when the ratio of the 2 two polymers was changed to 8 : 2 or 2 : 8 and/or when other 3 polymer mixtures were used, such as cellulose - starch, cellulose -4 cellulose sulfuric acid ester, cellulose - carrageenan, cellulose -alginic acid, cellulose - pectic acid, cellulose - guar gum, 6 cellulose - ~um arabic, starch - alginic acid, starch - pectic 7 acid, and when mixtures of three or more of the above polymers 8 were used.

If the methanol used for separating films and fibers 11 was replaced by ethanol, isopropanol, aqueous acetone, and 12 methanol - acetone mixtures, films, fibers, and granules of the 13 polymers were obtained equally well.

Films, fibers, and granules containing an acidic 16 polyhydroxypolymer were neutralized by immers;ng in aqueous or 17 anhyarous methanol containing ammonium, sodium, or potassium 18 hydroxides, propylamine, dibutylamine, trilaurylamine, or tri-19 ethanolamine. Softness, flexibility, water sensitivity, and other characteristics of the products depended to some extent 21 on the base used for neutralization.

Cellulose (10 g,) was suspended in 200 ml. D~ and 26 about 15 g. dinitrogentetroxide introduced to obtain a clear 27 solution. A solution of 10 g. of polyvinyl acetate in 50 ml.
28 ethylacetate was added, and from this mixture, films and fibers 2g were prepared in a manner describcd under Example XVIII Films and fibers were obtainable equally well when starch, alginic acid, guar gum, or hydroxypropyl cellulose was substituted for 2 cellulose and/or cellulose nitrate, cellulose acetate, poly-3 acrylic ester, or polymethacryli~ ester substituted for poly-4 vinyl acetate, 6 In another experiment, the polyvinyl acetate solution - 7 was replaced by a solution of 10 g. of nylon in hot DMF and, in 8 a further experiment, by 10 g. polyethylene glycol in DMF, and 9 films and fibers were prepared with equal success.

~1 Changing the ratios of the polymers in the solutions 12 did not adversely affect film and fiber formation.

16 Polyvinyl alcohol (10 g.) was suspended in 80 ml.
17 D~C, about 10 g. dinitrogentetroxide introduced with mechanical 18 stirring and under exclusion of moisture, and stirring continued 19 until a clear solution was obtained. Then, a solution of 10 g.
polyacrylonitrile in 50 ml. DMAC was added and the resulting 21 clear solution of the polymer mixture used for film and fiber 22 formation. A mixture of benzene - isopropanol - water was used 23 for separation of the polymers, and isopropanol was used for 24 washing.
26 Essentially similar results were obtained when the 27 polyacrylonitrile solution was replaced by solutions of methyl 28 vinyl ether - maleic anhydride copolymer, polyester, polyvinyl 29 chloride, poly~ctone, phenolic resin, ethylene - acrylic acid copolymer, or polystyrene, or by a solution of two of such ,:. ..-, .. .

10518~30 1 polymers and/or polyvinyl alcohol was substituted by guar gum 2 or a mixture of cellulose and starch.

4 EX~MPL~ XXII

6 Hydroxyethyl cellulose (10 g.) was solubilized in a 7 mixture of 85 ml. DMF and 15 ml. pyridine by introducing a 8 sufficient amount of dinitrogentetroxide and the resulting 9 solution mixed with a solution of polyvinyl hydrogenphthalate (10 g.) in DMAC. The resulting solution of the two polymers 11 then was spread on glass plates and the plates immersed in aqueous ethanol containing hydrochloric a~id in excess to the 13 amount of pyridine on a molar basis. The films then were 14 removed, washed with ethanol, kept in ethanol containing a small amount of ammonia, and dried.

17 ~XAMPLE XXIII

19 Cellulose (10 g.) was solubilized in a mixture of 50 ml. DMF and 50 ml. ethyl acetate with a sufficient amount of 21 dinitrogentetroxide, and a solution of 12 g. cellulose acetate 22 in 100 ml. ethyl acetate was added. The resulting solution was 23 spread on glass plates in a low humidity chamber, most of the 24 solvent removed by evaporation under reduced pressure, and the plates immersed in methanol. The films were washed with methanol 26 and dried.

28 Similar results were obtained when polyvinyl acetate 29 was substituted for cellulose acetate and/or alginic acid for cellulose.

r~................. ~ 9 32 ~ ~
,

Claims (30)

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

1. A process for preparing a nitrite ester of cellulose, said process comprising:
reacting cellulose which contains an activating amount of water in an amount of 4 percent by weight or more with dinitrogentetroxide or nitrosyl chloride in the presence of a swelling or solubilizing solvent for the resulting cellulose nitrite and a proton acceptor;
said water being substantially uniformly distributed throughout the cellulose reactant;
said reaction being carried out with agitation at a reaction temperature below 50°C., and said solvent being present in an amount sufficient to provide at least 3 parts by weight of solvent for each part of cellulose.

2. The process of Claim 1 including: reacting said 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; said reaction being carried out in the presence of dinitrogen tetroxide; reacting said mixed ester with an alcohol containing up to 10 carbon atoms; said alcohol reacting with the nitrite groups in said mixed ester and also with dinitrogen tetroxide to simultaneously produce a sulfate ester of cellulose and an alkyl nitrite.

3. The process of Claim 1 including: reacting said 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; said reaction being carried out in the presence of dinitrogen tetroxide; adding water to said reaction mixture and neutralizing the sulfuric acid ester of cellulose through addition of an inorganic base to simultaneously prepare a sulfate ester of cellulose and a mixture of an inorganic nitrite with an inorganic nitrate.

4. The process of Claim 1 wherein the water content of the cellulose reactant ranges from 4 to 12 percent by weight of water.

5. The process of Claim 4 wherein said solvent is a proton acceptor that is a weak tertiary amine base, a N,N-dialkylacylamide, or mixtures thereof.

6. The process of Claim 4 wherein said solvent is also said proton acceptor and said solvent is N,N-dimethylformamide.

7. The process of Claim 4 wherein the reaction temperature is below 30°C.

8. The process of Claim 1 including the initial step of treating the cellulose which contains an activating quantity of water with a highly polar aprotic solvent to reduce the water content in said cellulose to as low as less than 4 percent by weight of the cellulose, and thereafter reacting the treated cellulose with dinitrogentetroxide or nitrosyl chloride in the presence of a swelling or solubilizing reaction solvent for the cellulose nitrite ester and a proton acceptor.

9. The process of Claim 8 wherein said reaction solvent is also said proton acceptor and is a weak tertiary amine base, or N,N-dialkylacylamide, or mixtures thereof.

10. The process of Claim 8 wherein said highly polar aprotic solvent is N,N-dimethylformamide, N,N-dimethylacetamide or pyridine.

11. The process of Claim 8 wherein said highly polar aprotic solvent is also said reaction solvent and said proton acceptor, and said aprotic solvent is N,N-dimethylformamide.

12. The process of Claim 8 wherein the reaction temperature is below 30°C.

13. The process of Claim 1 including the additional step of reacting of nitrite ester of cellulose with nitric acid at a temperature of 60 to 110°C to produce a cellulose nitrate ester.

14. The process of claim 1 including the additional step of reacting the nitrite ester 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 nitrite:sulfate ester with a protic solvent to remove residual 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.

15. The process of Claim 14 wherein the degree of nitrite substitution of the nitrite ester is 2 to below 3 and the degree of sulfate sub-stitution of the sulfate ester ranges up to 1.1.

16. The process of Claim 14 wherein the degree of nitrite substitution of the nitrite ester is less than 2 and the degree of sulfate sub-stitution of the sulfate ester is greater than 1.1.

17. The process of Claim 8 including the additional step of reacting the nitrite ester of cellulose with nitric acid at a temperature of 60 to 110°C. to produce a cellulose nitrate ester.

18. The process of Claim 8 including the additional step of reacting the nitrite ester 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 mixture nitrite:sulfate ester with a protic solvent to remove residual 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.

19. The process of Claim 18 wherein the degree of nitrite substitution of the nitrite ester is 2 to below 3 and the degree of sulfate sub-stitution of the sulfate ester ranges up to 1.1.

20. The process of Claim 19 wherein the degree of nitrite substitution of the nitrite ester is less than 2 and the degree of sulfate substitution of the sulfate ester is greater than 1.1.

21. The process of claim 1 including:
contacting the cellulose nitrite ester solution in the presence of an acidic catalyst with a suitable protic solvent in such a manner that films, fibers, or other shaped articles of essentially unmodified cellulose are formed.

22. The process of claim 21 wherein a mixture of a polyhydroxy polymer and said cellulose containing an activating amount of water are reacted with dinitrogen tetroxide or nitrosyl chloride to obtain a solution of the nitrite ester of said polyhydroxy polymer and said cellulose nitrite ester, and contacting said nitrite ester solution in the presence of an acidic catalyst with a suitable protic solvent in such a manner that films, fibers or other shaped articles are formed which are composed of an intimate mixture of the essentially unmodified polyhydroxy polymer and the essentially unmodified cellulose.

23. The process in accord with claim 22 in which the polyhydroxy polymer includes one or more polysac-charides.

24. The process of claim 22 in which the polyhydroxy polymer includes one or more synthetic polyhydroxy polymers.

25. The process of claim 24 in which the synthetic polyhydroxy polymer is a polyvinyl alcohol.

26. The process of claim 24 in which the polyhydroxy polymer includes partially substituted polysac-charides.

27. The process of claim 21 including:
forming a solution in a suitable medium which contains said cellulose nitrite ester and one or more polymers lacking hydroxyl groups and then contacting said solution in the presence of an acidic catalyst with a suitable protic solvent in such a manner that films, fibers and other shaped articles are formed which are composed of an intimate mixture of essentially unmodified cellulose and the polymer or polymers lacking hydroxyl groups.

28. The process of claim 22 including:
forming a solution in a suitable medium which contains a nitrite ester of said one or more polyhydroxy polymers, a cellulose nitrite ester, and one or more polymers lacking hydroxyl groups and then contacting said solution in the presence of an acidic catalyst with a suitable protic solvent in such a manner that films, fibers and other shaped articles are formed which are composed of the essentially unmodified one or more polyhydroxy polymers, the essentially unmodified cellulose and one or more polymers lacking hydroxyl groups.

29. Films, fibers and other shaped articles formed in accord with the process of claims 21 or 22.

30. Films, fibers and other shaped articles formed in accord with the process of claims 27 or 28.