DD152565B1 - PROCESS FOR PREPARING POLYHYDROXYPOLYMERSULFATESTERS, IN PARTICULAR CELLULSESULFATESTERS - Google Patents

Description

Field of application of the invention

Sulfuric acid half esters of cellulose, in particular high molecular weight esters, find use as an additive component to bone glue, which does not flow as a suspending agent for oil drilling mud, as a thickener of the water phase in the secondary oil extraction in the water rubbing process, as a softener and emulsifier in cosmetics, as a thickening and stabilizing agent in detergents, further in wax emulsions, paints and photographic emulsions, as a reaction component with proteins and not least as ion exchangers and water-soluble paper auxiliaries. For non-soluble, but highly water-swelling cellulose sulfates there are applications as absorbent pads in diapers or towels.

Characteristic of the known technical solutions

It is known that esters of polyhydric polymers with sulfuric acid half ester groups, in particular esters of cellulose, can be prepared by reacting the hydroxyl-containing polymer with mixtures of: sulfuric acid with lower aliphatic alcohols (US Pat. No. 2,539,451, Petropavlovskij, G .: Preparation and Properties of Some Ionic Cellulose Ethers and -ester, fiber research and textile technology 24 [1973] p44-57, US-PS 2612498, US-PS 2753337), sulfuric acid with diethyl ether (DD-PS 112456), sulfuric acid with acetic anhydride and / or aliphatic carboxylic acids (US-PS 2,683,143 , U.S. Patent No. 2969356, US Patent 3086007, US Patent 3075963, US Patent 4005251), sulfuric acid with SO ₃ and liquid SO ₂ (CA-P 535,342), chlorosulfonic acid with liquid SO ₂ (Asami, R., Tokura, N., J. Chem. Soc., Japan, Ind. Chem. Sect. 62 [1959] p. 1593), chlorosulfonic acid with pyridine (DE-AS 1173079, DE-OS 1 793136, FR-P 1 477401, DE-OS 1443903, DE-OS 1 518 850), sodium chlorosulfonate with acetic anhydride and acetic acid (US Pat. No. 2,969,355), of fluorosulfonic acid with benzene / ethanol (SU Pat. No. 2,06567), of sulfur trioxide with liquid SO ₂ (Asami, R. and Tokura, N .: J. Chem. Soc. Japan, Ind. Chem. Sect. 62 [1959] p. 1593), of sulfur trioxide with chlorinated hydrocarbons (Vasilera, OA, Sharkov, VI: Nauch, Tr., Leningrad Lesotekh.Akad. [1972] 162, pp. 66-68), of sulfur trioxide with a tertiary amine (JP-PS 7489786, JP-PS 7489787, JP-PS 7616392, JP-PS 7 6148782, JP-PS 76148783, DE-OS 1 643011, DE-OS 1 908353, DE-AS 1 468964), of sulfur trioxide with dimethyl sulfoxide (US Pat. No. 3507855, DE-OS No. 1 668542), sulfur trioxide with an N-dialkylamide (SW-AS 319606, DE-OS 1 902373, US Pat. No. 3,622,069, US Pat. No. 3,633,520, US Pat. No. 3,639,665, DE -OS 1 543120, US-P 3544555).

Disadvantages of these methods are that in some cases a strong chain length of the polyhydroxypolymers occurs, a considerable excess of sulfuric acid, sulfuric acid derivatives or sulfuric anhydride is required, the sulfating agents z.T. are very expensive and technically difficult to access, often to reduce the chain length degradation considerably below room temperature or to achieve a sufficiently rapid reaction rate at a greatly elevated temperature must be worked. Another disadvantage of these methods is that, due to the heterogeneous or quasi-homogeneous reaction, they lead to incomplete and, in particular, uneven esterification of the polyhydroxy polymers, resulting in e.g. Insufficient solubility in water and compatibility with various metal ions result in a significant limitation of the scope of such esters. Significant progress in the preparation of the sulfuric acid half-esters of polyhydroxy polymers of very low chain length has been made by the patents and publications of Schweiger (DE-OS 2120964, CA-PS 979 577, DE-OS 2 530 541, US-PS 4035569, Tappi 57 [1974] S. 86-90), after which the resulting in the release of the polyhydroxy in the dinitrogen tetraoxide / N-dialkylamide nitrite ester of the polymer in the homogeneous medium with sulfur trioxide or a complex of sulfur trioxide and N-dialkylamide, pyridine, dimethyl sulfoxide, inter alia, in particular N, N-dimethylformamide becomes. It is stated that ζ. B. cellulose sulfate esters with DS values> 0.3 are completely water-soluble and have very high solution viscosities.

Disadvantages of this method are that the very aggressive, extremely hygroscopic and therefore difficult to handle sulfur trioxide is used for sulfation, the polyhydroxypolymere to achieve completely water-soluble sulfate ester must first be dissolved in dinitrogen tetraoxide / DMF mixture and thus a relatively high N ₂ O ₄ excess is required. Another disadvantage is that in order to avoid a stronger chain length degradation, the sulfation below the room temperature at 5 to 15 ° C must be performed.

Object of the invention

The aim of the invention is, using industrially customary and easy to handle starting materials, when using low reagent concentrations PolyhydroxypolymersuIfatester, in particular cellulose sulfate ester to produce.

Explanation of the essence of the invention

The object of the invention is to achieve by homogeneous or quasi-homogeneous reaction to completely water-soluble sulfuric monoesters of polyhydroxy, in particular cellulose sulfate esters with DS values> 0.25, low chain length degradation and high solution viscosities.

According to the invention, this object is achieved in that for the production of Polyhydroxypolymersulfatestern, in particular cellulose sulfate, with adjustable average degree of substitution by reacting polyhydroxypolymers with sulfating in the dinitrogen tetraoxide containing organic aprotic liquids at reaction temperatures of 0 to 50 ° C, a liquor ratio of 1: 3 to 1 : 100, precipitation in the presence of protic liquids and isolation in a conventional manner using sulfating agent as the sulfating agent, the reaction being carried out at a molar ratio of sulfur dioxide to polyhydroxy monomer unit of 0.1 to 10 and a molar ratio of N ₂ O ₄ known per se To the polyhydroxy polymer monomer unit of 0.1 to 10 is performed.

A molar ratio of SC 1 to the monomer unit 0.5 to 4 and of N ₂ O _{4 to the} monomer unit 0.5 to 6 is preferably desired.

The Polyhydroxypolymersulfatester obtained is then isolated in the presence of protic liquids, preferably by precipitation.

In the process according to the invention, the partially or completely substituted very reactive polyhydroxypolymnitritester present in the system dinitrogen tetraoxide / organic aprotic liquid is converted to the polyhydroxypolymer sulfate ester by utilizing the redox reactions between sulfur dioxide and dinitrogen tetraoxide or the secondary products resulting from the nitrite ester formation, using the redox reactions taking place in an aprotic medium. A great advantage of the process according to the invention is that a uniform distribution of the sulfate ester groups via the macromolecule takes place both in the quasi-homogeneous reaction regime in the presence of low, non-solvent dinitrogen tetraoxide concentrations and in the case of homogeneous transesterification of the polyhydroxypolyester nitrite ester dissolved in the reaction medium with excess dinitrogen tetraoxide by the sulfation agent.

This makes it possible for the first time, even after an initially heterogeneous sulphation process, e.g. Cellulosesulfatester are produced, which have unexpected properties, as they are already completely soluble in water at substitution levels of sulfate ester groups> 0.25 and have high solution viscosities.

Other significant advantages of this method are that the sulfation agent compared to sulfur trioxide much less aggressive and hygroscopic and gaseous at room temperature, good manageable sulfur dioxide is used, which facilitates working under extensive exclusion of moisture through the simple drying and low hygroscopicity of sulfur dioxide, as well in the presence of small amounts of water, due to the very low aggressiveness of the sulfur dioxide or of the sulphurous acid which forms with water, gentle sulphation is possible. Furthermore, in contrast to the sulfation with sulfur trioxide in this method advantageously the reaction components dinitrogen tetraoxide, sulfur dioxide and the polyhydroxy in any order and in the intended for the sulfation reaction total amount to the presented aprotic reaction medium can be added quickly without external cooling of the reaction mixture is required. Also during the esterification process, no cooling is required under suitable concentration conditions, but can be advantageously used at room temperature or at temperatures up to about 40 ° C, without a noticeable degradation occurs.

From an economic point of view, it is particularly advantageous that substances which are used industrially as starting materials are used. As starting polymers of the process, it is possible to use all polymers which contain free hydroxyl groups:

e.g. Carbohydrates such as cellulose, starch, dextran, xylan, hemicellulose; Polyuronic acids such as alginic acid and pectinic acid; synthetic polyhydroxy polymers such as the polyvinyl alcohols; Polyhydroxypolymer already partially containing ether or ester groups such as e.g. Carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, partially saponified cellulose acetate, cellulose formate, carboxymethyl starch, alginic acid acetate or propionate and partially hydrolyzed polyvinyl acetate.

The process according to the invention comprises the following reaction steps: The starting hydroxypolymer is suspended in a suitable aprotic medium. Suitable liquids are e.g. Dimethylsulfoxide, N, N-dialkyl, such as Ν, Ν-dimethylacetamide and preferably Ν, Ν-dimethylformamide or mixtures thereof. Solvents can be added to these aprotic media which can dissolve polymer esters, such as e.g. For example, acetone, methyl ethyl ketone, ethyl acetate, ethyl formate

u. Ä. Or their mixtures. The weight ratio of aprotic medium to polymer can be varied within wide limits.

The addition of the reagents dinitrogen tetraoxide and sulfur dioxide can be done in any order and in different forms. So z. B. dinitrogen tetraoxide are first introduced with vigorous stirring in gaseous form in the polymer suspension or added as a solution in a suitable aprotic medium and then sulfur dioxide are added in gaseous form or in solution. On the other hand, first sulfur dioxide and then dinitrogen tetraoxide or both reagents can be dissolved simultaneously in gaseous form or in a suitable liquid or added as a mixed solution of both gases.

The addition of the reagents can be carried out very rapidly in the total amount provided. It is also possible to introduce the starting polymer directly into the reaction medium containing one or more reagents without swelling and suspending. The molar ratio of dinitrogen tetroxide to polyhydroxypolymer monomer unit is from 0.1 to 10 preferably from 0.5 to 6 and from sulfur dioxide to the monomer unit from 0.1 to 10, preferably from 0.5 to 4, The reaction is preferably carried out while the reaction mixture is being stirred, the addition of the reagents having to be carried out to a large extent exclusion of moisture

The sulfation is carried out at ⁰ ° C to 5O ⁰ C, preferably at 20 ° C to 40 ° C, carried out under suitable concentration ratios, the reaction proceeds at room temperature, without any external temperature control is required

For certain other reagent concentrations, a temperature of the reaction mixture to 25 to 40 ⁰ C is required or especially at high sulfur dioxide levels with progressive reaction external cooling is necessary, the reaction temperature below 5O ⁰ C halt The required reaction times are 10 minutes to 10 hours, preferably 30 minutes to 5 hours, and are dependent on the swelling stage of the polyhydroxy polymer, on the N ₂ O ₄ and SO ₂ concentrations and on the reaction temperature

After completion of the reaction, excess nitrous gases and sulfur dioxide are optionally removed by suction from the reaction mixture in vacuo

The undissolved or partly or completely dissolved in Reakionsmedium Polymernitntschwefelsurester is now reacted with a protic medium such as water, methanol or ethanol, with elimination of the nitrite ester groups of the pure polymeric sulfuric acid ester formed The protic liquids can be added in stoichiometric amounts or in excess

To separate the polymer sulfate ester, a liquid not releasing the polymer ester, such as acetone or methanol, is added in one to four times the amount of the reaction mixture. However, it is also possible to use a mixture of protic liquid, such as water or alcohol, which simultaneously splits off the nitrate ester groups The ester is separated and washed with fresh precipitant. The next step of the process involves neutralization of the polymer sulfuric acid ester with a base to form a salt. Since the acidic form of the polymer sulfate ester degrades upon storage, it is preferably converted to a neutral salt Hydroxides, carbonates and bicarbonates of the alkali and alkaline earth metals but also ammonia, ammonium and quaternary ammonium compounds are preferably suitable for the neutralization. The neutralization agent can be used directly or as a solution or suspension in one Neutralization can be carried out in aqueous solution of the separated polymer sulfate ester or as a heterogeneous reaction of the isolated ester, preferably with methanolic sodium hydroxide solution. However, it can also be carried out directly in the reaction medium without changing the solution state of the polymer ester ζ Β It is also possible to carry out the cleavage of the nitrate ester groups, neutralization and precipitation of the polymer sulfate ester salt in one step, by adding directly to the reaction mixture by addition of aqueous sodium hydroxide solution and subsequently isolating the salt of the polymer sulfate ester by adding a dropping agent such as methanol, ethanol and / or acetone Reaction mixture, a solution or suspension of the neutralizing agent, for example in methanol and / or acetone, is stirred or vice versa For separating the optionally dissolved in the neutralized mixture Polymerulfatestersalze w A precipitating agent such as acetone or an ahphatic alcohol is added with stirring or the mixture is poured into the precipitating agent in a thin stream. The precipitated sulfate ester salts of the hydroxyl-containing polymers can be washed with hydrous precipitants and dewatered in suitable anhydrous liquids. Finally, the polymer ester salt is isolated and dried

embodiments

Example 1 Homogeneous sulfation of the cellulose

30g of bleached cotton and give lamp (Cuoxam DP = 1950) were dried at 105 ⁰ C and pre-swollen for 12 hours in 1 200ml dimethylformamide at room temperature

To the suspension 45.5 g N ₂ O ₄ are dissolved in DMF, with stirring inflicted After dissolution of cellulose to become a highly viscous clear solution at 30 "C 8g sulfur dioxide dissolved in DMF was added, stirred for 2 hours, further added 8 g of sulfur dioxide and a further 2 hours The liquor ratio of cellulose to the reaction mixture is 1: 1 methanol is added to the highly viscous solution and precipitated by addition of 21% acetone of the sulfuric acid half ester of cellulose. After washing twice with acetone, the product is suspended in a mixture of 11 acetone and 500 ml of methanol, in a heterogeneous phase methanolic sodium hydroxide solution, washed twice with 80% aqueous methanol, separated and dried The completely water-soluble product contains 4.34% sulfur, corresponding to a DS of sulfate ester groups of 0.26 and 4.26% sodium, resulting in a degree of substitution of additional acidic groups of 0 09 results A 1% aqueous solution has at 20 ⁰ C has a relative viscosity of 2800

Example 2

Quasihomogene sulfation of cellulose

30 g dried at 150 ⁰ C cotton sinters (Cuoxam DP = 1 500) are pre-swollen for 1 hour at room temperature in 800 ml of DMF and 30g dinitrogen tetroxide dissolved in DMF, added with stirring at 30 ° C 24g sulfur dioxide dissolved in DMF with intensive mixing added The liquor ratio amounts to 1 40 the stirring of the mixture is interrupted and 2 ml Schwefelsau Reder density ~ 1.92 g / cm ³ at 20 ⁰ C was added after about 1 hour is stirred periodically until a clear high viscous solution is produced, the solution is in the thin beam in a Fallungsgemisch , consisting of acetone and methanol in a ratio of 2 1, poured in with vigorous stirring, the cellulose semi-ester separated and washed repeatedly with fresh precipitant The precipitate is dissolved in ice water, neutralized with aqueous sodium hydroxide solution, precipitated with acetone, washed with methanol and dried

The completely water-soluble sodium cellulose sulfate containing 4.5% sulfur, corresponding to a DS = 0.30 and 7.7% sodium, corresponding to a content of additional acidic groups of DS 0.40 The relative viscosity of a 1% aqueous solution is 20 ⁰ C 2000

Example 3

Quasihomogeneous sulfation of starch

Pregelatinized 2g and at 60 ⁰ C in vacuum dried Starke 24 hours at room temperature, 2.3 g of pre-swollen dinitrogen tetroxide, dissolved in DMF in 50 ml of DMF, and then 1.6 g of sulfur dioxide, dissolved in DMF, are added with stirring to 30 ⁰ C. After addition of 0.2 ml of sulfuric acid of density 1.92 g / cm ³ at 20 ⁰ C, the mixture

⁰ C allowed to stand with occasional stirring for 12 hours at room temperature at 3O 4 hours Then, the Starkesulfatester is precipitated with an acetone / diethyl ether mixture of 3 1 parts by volume and washed, neutralized the separated product in ice-cold methanol with aqueous sodium hydroxide solution, after the addition of acetone and Diethyl ether separated, washed with acetone and dried. The water-soluble product contains 4.5% sulfur corresponding to a DS of sulfate ester groups of 0.28 and 5.2% sodium, corresponding to a DS of additional acidic groups of 0.17

Example 4

Sulfation of dextran

5 g of dextran are preswollen in 300 ml of DMF for 1 hour at room temperature, then 6g N ₂ O ₄ and then 4g SO ₂ gaseous under stirring initiated with occasional stirring, the mixture is allowed to stand for 15 hours at room temperature and then precipitated by acetone addition dextran sulfate from the clear solution , separated and washed with an acetone / methanol mixture of 3 1 parts by volume 3 times In ice-cold methanol, the product is neutralized with aqueous sodium hydroxide solution, after acetone addition separated, washed with methanol and dried The product contains 1.9% sulfur, corresponding to a DS = 0 , 10 and 2.1% sodium, corresponding to a DS of additional acidic groups of 0.06.

Example 5

Sulfation of xylan

5 g of xylan are preswollen in 300 ml for 24 hours at room temperature and then 22.5 g of N ₂ O ₄ , dissolved in DMF, added with stirring After dissolving the xylan 6g sulfur dioxide, dissolved in DMF, at 3O ⁰ C is added, after 5 Hours reaction time, the formed xylan ester is precipitated with ester and washed, separated and neutralized in ice-cold methanol with aqueous sodium hydroxide solution After acetone addition, the product is separated, washed with methanol / acetone = 1 3 parts by volume and dried The sodium xylan sulfate containing 3.44% sulfur and 3, 86% sodium

Example 6

Sulfation of polyvinyl alcohol

2g of polyvinyl alcohol are dried at 105 ⁰ C and pre-swollen in a vessel with 50 ml of DMF for 1 hour at room temperature, Then, 3.6 g of N ₂ O _4, and 2.4 g SO _2, dissolved in DMF, added with stirring After 5 hours reaction time at 30 ⁰ C is the polymer sulfate ester formed with an acetone / Diathylather mixture of 3 1 parts by volume of the solution and washed, neutralized in ice-cold methanol with aqueous sodium hydroxide solution, separated after addition of acetone and Diathylather, washed with diethyl ether and dried

The product contains 5.5% sulfur, corresponding to a DS = 0.1 and 8.7% sodium, corresponding to a content of additional acidic groups of -0.06

Claims (2)

1. A process for the preparation of Polyhydroxypolymersulfatestern, in particular of Cellulosesulfatestem with adjustable average degree of substitution by reacting polyhydroxypolymers with sulfating in dinitrogen tetraoxide containing organic aprotic liquids at reaction temperatures of 0 to 50 ° C, a liquor ratio of 1: 3 to 1: 100, precipitation in the presence protic liquids and isolation in customary, characterized in that as sulfating agent sulfur dioxide is used, wherein the reaction at a molar ratio of 0.1 to 10 and a known molar ratio of N ₂ O ₄ ZUr polyhydroxypolymer monomer unit from 0.1 to 10 is performed. 2. The method according to claim 1, characterized in that the molar ratio of SO ₂ to the monomer unit 0.5 to 4 and of N ₂ O ₄ to the monomer unit is 0.5 to 6.