KR970005475B1 - PROCESS FOR THE PRODUCTION OF POLYLACTONES OF POLY£Ñß-HYDROXY-(ACRYLIC,CROTONIC OR ACRYLIC + CROTONIC) ACID | - Google Patents

Abstract

None.

Description

Method for preparing polylactones and corresponding salts of poly- [α-hydroxy- (acrylic, croton, or acryl + croton) acid]

The present invention relates to polylactones of poly- [α-hydroxy- (acrylic, croton or acryl + croton) acid] and corresponding poly- (α-hydroxy-acrylate, crotonate, or acrylate + croto Nate).

According to the invention, alkyl acrylates or alkyl crotonates or mixtures thereof are chlorinated with the corresponding 2,3-dichloropropionic acid alkylesters or 2,3-dichlorobutanoic acid alkylesters or mixtures thereof; The resulting 2,3-dichloropropionic acid alkylester, or 2,3-dichlorobutanoic acid alkylester or mixture thereof is treated with an aqueous base to convert to a dehydrochlorination reaction and the corresponding salt; Then acidified; Polymerize; Under acidic conditions, poly-[[alpha] -hydroxy- is carried out without conversion of the intermediate product, consisting of the steps of converting to polylactone of poly-[[alpha] -hydroxy- (acrylic, croton or acrylic + croton) acid]. A method for producing a polylactone of (acrylic, croton, acrylic + crotonic acid) is provided.

Alkyl ester residue as the C _1-4 - alkyl is, in particular, n- butyl, n- propyl, ethyl or methyl is more preferred, and most preferred are ethyl and methyl-alkyl are preferred, and straight-chain C _1-4.

Chlorination of the starting acrylic ester, crotonic ester, or mixtures thereof is conveniently carried out in the absence of a solvent (also water). The addition of chlorine is carried out by the direct addition of gaseous chlorine, which is advantageously carried out in the presence of a chlorination catalyst. Preferred catalysts are N-substituted amides of carboxylic acids, advantageously C _1-9 -aliphatic carboxylic acids, preferably C _1-4 -aliphatic carboxylic acids, in particular acetic acid or formic acid. The amide moiety may have one or two C _1-12 -hydrocarbon residues, preferably one or two C _1-4 -hydrocarbon residues, in particular methyl or ethyl. Particularly preferred as a catalyst is dimethylformamide. The chlorination catalyst is conveniently used at a concentration of 0.01-5% by weight, preferably 0.05-% by weight, based on the weight of the ester. The chlorination treatment is conveniently carried out at a temperature of 0-70 ° C., preferably 15-50 ° C. under light blockage. Excess chlorine, for example up to 10 mole percent, may be used, but a stoichiometric theoretical amount of chlorine is sufficient to meet the optimum degree of chlorination in a closed container.

Immediately thereafter, without separation, the resulting 2,3-dichloropropionic acid, or -butanoic acid alkylester, or mixtures thereof is subjected to dehydrochlorination and saponification in the presence of an aqueous base. Suitable bases include alkali metal hydroxides such as NaOH, KOH or LiOH or ammonium hydroxide, with ammonium hydroxide and especially sodium hydroxide being preferred. The dehydrochlorination reaction and saponification are carried out at about the same time, advantageously at -10- + 60 ° C, preferably 0-60 ° C, in particular 20-40 ° C. The base is convenient to participate in a quantitative ratio such that alkaline conditions are maintained during the overall dehydrochlorination and saponification process. It may also be added in portions, or continuously, in an amount or excess of stoichiometric theory, such as up to 70 mol% per mole of ester. Dehydrochlorination and saponification can also be carried out in an aqueous medium containing an inert salt. In the case of using ammonium hydroxide as the base, it is advantageous to add alkali metal halides, preferably sodium chloride, to the reaction mixture; It is preferred to add concentrated brine, such as 20-30% sodium chloride solution, to the reaction mixture. The concentration of 2,3-dichloro-ester in the aqueous reaction mixture is advantageously 5-70% by weight, preferably 5-20% by weight, particularly preferably 7-15% by weight.

After completion of the dehydrochlorination and saponification treatment, the reaction mixture is added with an organic strong or inorganic strong acid, such as sulfuric acid, hydrochloric acid, phosphoric acid or aromatic sulfonic acid such as p-toluene-sulfonic acid, to pH7, preferably pH 1-5. Acidified with hydrochloric acid being preferred. The temperature is within the range -10- + 60 ° C., preferably 0-40 ° C. It is advantageous to acidify only to the extent that a mixture of the free acid and the corresponding alkali metal or ammonium salt is obtained, taking into account the subsequent synthesis step. The acid should then be added in an amount sufficient to neutralize the excess base and convert only a portion of the α-chloroacrylate or αchlorocrotonate, or mixtures thereof to the corresponding free acid form. In general, it is preferred to add 0.4-2 mol, preferably 0.4-1 mol of acid (preferably hydrochloric acid) per mole of alkyl ester.

α-chloroacrylic acid, or α-chlorocrotonic acid, or mixtures thereof are obtained in free acid form or mixed with salt form depending on pH conditions.

In the case where the monomeric acid or acid salt is to be temporarily stored in the solution without polymerization, it is advantageous to add a polymerization inhibitor, conveniently hydroquinone or hydroquinone monomethyl ether. At this time, it is convenient to add the inhibitor in an amount of 30-100 ppm based on the weight of the monomer.

The polymerization residual of (alpha) -chloroacrylic acid or (alpha) -chlorocrotonic acid (copolymerization reaction in the case of a mixture of the two acids) is carried out under acidic conditions, preferably pH1-5, more preferably pH in the range of 1-3.5 It is convenient to carry out in the same aqueous medium in which the monomeric acid is obtained. Catalysts commonly used in polymerizations, for example azo compounds, in particular 4.4'-azo-bis (4-cyanopentanoic acid) or azo-bis-iso-butyronitrile, cumene hydroperoxide, sodium perborate, hydrogen peroxide Or a redox system containing, for example, sodium dithionite or sodium bisulfite, as a peroxy compound such as potassium peroxydiruvate, or the aforementioned peroxy compound and reducing agent as oxidant. Among the catalysts mentioned above, peroxy compounds, especially hydrogen peroxide, are preferred; At this time, hydrogen peroxide may be used as it is or H ₂ O ₂ -producing compound, for example in the form of potassium peroxide, it is preferable to use hydrogen peroxide directly. The catalyst is used in conventional amounts, for example at least 0.0001 moles per mole of monomer. In the case where the catalyst is an azo compound, it is preferable to use it in an amount of 0.0001-0.005 mol, more preferably 0.0002-0.003 mol per unit mole of monomer. When the catalyst is a peroxy compound (particularly H ₂ O ₂ ), it is preferable to use it in an amount of 0.005-3.25 moles per mole monomer unit. To prepare a polymer having an average molecular weight (Mw) of sodium salt 2000-10,000 (preferably 3000-10000, more preferably 4000-8000), preferably 0.1-3.25, more preferably 0.2-3 per mole of monomer. Use in molar amounts. The polymerization reaction (or copolymerization reaction) is conveniently carried out at room temperature or higher and 150 ° C or lower, depending on the catalyst used. In the case where a redox system is to be used as a catalyst, the polymerization is carried out at a temperature of at least 20 ° C; The polymerization in the presence of a peroxy compound is carried out at a temperature of at least 40 ° C., preferably at 50 ° C .; When using an azo compound as a catalyst, it is convenient to carry out the polymerization reaction at a temperature of at least 60 ° C, preferably at least 70 ° C. If necessary, the polymerization reaction may be carried out in an autoclave. When using an azo compound as a polymerization catalyst, a preferable temperature range is 80-105 degreeC, and when using a peroxy compound as a polymerization catalyst, it is 70-90 degreeC, especially 80 degreeC.

Depending on the desired molecular weight, chain transfer agents, such as thioglycolic acid, methylthioglycolate, prior to the polymerization reaction. It is advantageous to add SH ₂ , nC _{2_4} mercaptan or water soluble alcohol in catalytic amounts.

The exchange of α-chlorine atoms with hydroxy radicals in the polymer is conveniently carried out within the same temperature range and under similar pH conditions as in the polymerization reaction described above. It is preferable to carry out the dehydrochlorination reaction almost simultaneously with the polymerization reaction. Substitution of the α-chlorine atom with hydroxy immediately proceeds to lactonation to produce polylactone almost simultaneously. The lactonation may be partial or complete lactonation.

The resulting polylactone is insoluble in water and is present in the solid state in the aqueous reaction medium. Separation and purification by any known method such as filtration or centrifugation and washing with water. If desired, an aqueous base such as an alkali metal hydroxide such as LiOH, NaOH or KOH, ammonium hydroxide or an amine such as tri- (β-hydroxy-C _2-3 -alkyl) amine, preferably May also convert polylactone to the corresponding poly- (α-hydroxy-carboxylic acid) salt by reacting with sodium hydroxide. The poly- (α-hydroxy-carboxylic acid) salt may also be obtained directly by adding an aqueous base to the polylactone-containing reaction mixture without intermediate separation of the polylactone.

The molecular weight of the resulting polymer depends on whether it is in lactone or salt form, and it is advantageous to have an average molecular weight (in the form of sodium salt) of 1,000-1,000,000, preferably 1,000-500,000, in particular 2,000-140,000.

Polylactones and the corresponding poly- (α-hydroxy-carboxylic acid) salts, in particular poly- (α-hydroxy-acrylic acid) salts, are known compounds. These are used, for example, as a promoter or dispersant which is an auxiliary agent of alkaline peroxy bleach solution.

The process of the invention is particularly advantageous for the production of polylactones from alkyl acrylates, or alkyl crotonates, or mixtures thereof in high yield without any intermediate separation step, and may be carried out in one vessel (1-pot). fair)

According to a preferred embodiment of the invention, polylactone of poly- (α-hydroxy-acrylic acid) or alkali metal poly- (α-hydroxy-acrylate) is preferred.

Hereinafter, the present invention will be described with reference to examples, and unless stated otherwise, all parts are based on weight, and all temperatures are based on degrees Celsius.

Example 1

86 g (1 mole) of methyl acrylate and 2.58 g of dimethylform amide are introduced into a three-neck flask at room temperature. The flask was rinsed with nitrogen and then 71 g of chlorine was passed through the mixture at a rate such that the temperature did not exceed 30 ° C. under light blocking at room temperature. As a result, methyl 2,3-diclopropionate with a purity> 94% is obtained.

A solution of sodium hydroxide (50 g) in 285 mL water was added dropwise to the resulting methyl 2,3-dichloropropionate over a period of 2 hours and 30 minutes at a rate such that the temperature was maintained at -5-0 ° C. After 2.5 hours, a solution of sodium hydroxide (50 g) in 70 ml water is added dropwise to the reaction mixture at a rate such that the temperature does not exceed 0 ° C. The resulting mixture is then stirred at 0 ° C. for 5 hours and then left at 0-15 ° C. overnight. The resulting sodium α-chloro-acrylate is converted to α-chloro acrylic acid by addition of 100 g of 36% HCl at 0 ° C., where the reaction mixture has a pH of 2.5.

Without separating α-chloroacrylic acid, the reaction mixture was heated to 95-98 ° C., and then a solution of 4,4′-azo-bis- (4-cyanopentanoic acid) (0.34 g) in 60 mL water was added with 2, The solid is precipitated by dropwise addition with stirring 3 drops of 2N sodium hydroxide over 15 hours under stirring. The reaction mixture is heated to reflux for 3 hours at boiling point. After cooling, the reaction mixture is filtered and the filter cake is washed with water and then dried. Microanalysis showed 81.4 g of polylactone of poly- (α-hydroxy-acrylic acid) in 90% yield.

Example 2

The procedure of Example 1 is repeated but modified as follows;

440 g of 26% sodium chloride saline is added to the resulting methyl 2,3-dichloro-propionate. After cooling to 0 ° C., 163.2 g of 25% ammonium hydroxide solution (calculated as NH ₃ ) is added dropwise over 1 hour at a rate to keep the temperature below 0 ° C. The reaction mixture is then stirred at 0 ° C. for 5 hours and then left at 0-15 ° C. overnight. The mixture was then retreated as described in Example 1 to give polylactone.

Example 3

258 g of methyl acrylate are introduced into a 750 mL four-neck flask and reacted with 7.7 g of dimethylformamide. After the flask was rinsed with nitrogen, 213 g of chlorine was passed through the mixture under light blockage. Raise the temperature from 20 ° C to 40-45 ° C but not to exceed 45 ° C. Once the chlorine addition was complete, the mixture was stirred again at 45 ° C. for 30 minutes to proceed with the reaction; Heat to 50 ° C. and discharge until no more chlorine is released from the medium. 477 g of methyl 2,3-dichloropropionate were obtained with purity> 97% and theoretical yield 99.6%. 159 g of the resulting methyl 2,3-dichloro-propionate and 239 g of water are introduced into a four-neck flask. Under stirring, 266 g of 30% sodium hydroxide solution is added dropwise for 3 hours at a temperature not exceeding 40 ° C. Subsequently, 50 g of 38% HCl solution was added dropwise again to the obtained clear sodium α-chloroacrylate solution at a temperature not exceeding 40 ° C. for about 60 minutes. The resulting pH is 2.5. The reaction mixture is heated to 95 ° C. and then a solution of 4,4′-azo-bis- (4-cyanopentanoic acid) (0.113 g) in 20 ml water is added dropwise over 1 hour. Once the catalyst addition is complete, the reaction mixture is again heated to 95 ° C. for 1 hour, cooled to room temperature, the resulting additive is filtered off, washed to remove leach, and then dried at 50 ° C. in vacuo. During the addition of the catalyst, the ester is subjected to polymerization, dehydrochlorination and lactonation continuously. After the reaction is completed, precipitation of polylactone of poly (α-hydroxy-acrylic acid) is substantially completed.

Yield: 73.5% white powder with a carbon atom content of about 45%

Example 4

The procedure of Example 3 is repeated, replacing 0.113 g of 4,4'-azo-bis- (4-cyanopentanoic acid) with 1 g of 37% hydrogen peroxide as catalyst. The yield, C-analysis and appearance of the resulting polylactones corresponded to those of the polymer obtained in Example 3.

Example 5

The procedure of Example 4 was repeated but the polymerization was carried out in the presence of 5 g of 40 vol% hydrogen peroxide at 75 ° C. instead of 95 ° C. and the reaction mixture was again treated at 75 ° C. for 1 hour to complete the reaction. The yield, C-analysis and appearance of the resulting polylactones were similar to those of the polymer obtained in Example 4.

Example 6

Repeat the procedure of Example 5, but add 0.003 g thioglycolic acid to the reaction mixture before adding hydrogen peroxide. The yield, C-analysis and appearance of the resulting polylactones were similar to those of the polymer obtained in Example 5.

Example 7

258 g of methyl acrylate is introduced into a 2.5 L flask equipped with a stirrer and a thermometer, and 7.7 g of dimethylformamide is added. 213 g of chlorine is then passed through the mixture under a block of light at a rate such that the temperature of the mixture does not exceed 40 ° C. Once the chlorination reaction is complete, excess chlorine is removed in vacuo. The resulting product is stirred with 503 g of demineralized water until the organic phase is properly dispersed in water. Then 800 g of 30% sodium hydroxide solution are added dropwise. The temperature is raised from 20 ° C to 40 ° C, cooled and maintained at 40 ° C. After 2.5 hours, the drop is completed. After maintaining the mixture again at 40 ° C. for 30 minutes, 180 g of 30% hydrochloric acid solution was added dropwise to the sodium α-chloroacrylate solution obtained at this temperature in 30 minutes. When the acid addition is complete, the pH of the reaction solution is about 2.5. Then 75 g of 35% hydrogen peroxide is added within 5 minutes and the reaction mixture becomes cloudy. The reaction mixture is continuously heated from 40 ° C. to 75 ° C. in 1 hour, stirred at 75 ° C. again for 3 hours and then cooled to room temperature. The obtained plelactone suspension is suction-filtered and washed with 9000 g of demineralized water. As a result, anhydrous 27% beige filter cake is dried at 110 ° C.

Example 8

The procedure of Example 7 is repeated to prepare a polylactone suspension. The resulting polylactone suspension is not filtered and immediately reacted with 450 g of 30% sodium hydroxide solution at 50-60 ° C. To the resulting slightly turbid reddish brown solution is added 7 g of 35% hydrogen peroxide and the whole mixture is stirred at 60 ° C. for 30 minutes.

The resulting sodium poly (α-hydroxy-acrylate) has a molecular weight (Mw) 4865.

Claims (6)

In the process for producing polylactone of poly- [α-hydroxy (acrylic, croton or acryl + crotonic acid), alkyl acrylates or alkyl crotonates or mixtures thereof are prepared with the corresponding 2,3-dichloropropionic acid alkyl esters or Chlorination with 2,3-dichlorobutanoic acid alkyl esters or mixtures thereof; The resulting 2,3-dichloropropionic acid alkylester or 2,3-dichlorobutanoic acid alkylester or mixtures thereof is treated with an aqueous base to convert to dehydrochlorination and the corresponding salts; Then acidified; Polymerize; The process of the above, consisting of the steps of converting to polylactone of poly- [α-hydroxy (acrylic, croton or acryl + crotonic acid)] under acidic conditions, without separation of the intermediate product. 2. Process according to claim 1, characterized in that the acrylic acid alkyl esters or crotonic acid alkyl esters or mixtures thereof are subjected to chlorination in the presence of N-substituted carboxylic acid amides used as chlorination catalysts. The process according to claim 1, wherein the dehydrochlorination reaction and the conversion into salt form are carried out in the presence of an aqueous solution of alkali metal hydroxide or ammonium hydroxide. The process according to claim 1, wherein the acidification treatment is carried out by adding an organic strong acid or an inorganic strong acid which can be brought to pH 1-5. 5. The process according to claim 1, wherein the obtained polylactone is hydrolyzed to the corresponding poly- (α-hydroxy-carboxylate) using an aqueous base. 6. The method of claim 5 wherein the polylactone is hydrolyzed without separation from the mother liquor.