JPH0220517A - Production of polylactone of poly(alpha- hydroxyacrylic acid and/or crotonic acid) - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides poly-(α-hydroxyacrylic acid and/or
or to the production of polylactones of crotonic acid and the corresponding poly(α-hydroxyacrylates and/or crotonates).

According to the invention, alkyl acrylates or alkyl crotonates or mixtures thereof can be chlorinated to give the corresponding 2
, 3-dichloropropionic acid alkyl ester or 2
, 3-dichlorobutyric acid alkyl ester, or a mixture thereof, and the resulting 2,3-dichloropropionic acid alkyl ester or 2,3-dichlorobutyric acid alkyl ester, or a mixture thereof is treated with an aqueous base to dehydrochloride, and the corresponding of poly(α-hydroxyacrylic acid and/or crotonic acid) into polylactones under acidic conditions, without isolating the intermediate products. A method for producing poly-(α-hydroxyacrylic acid and/or crotonic acid) is provided, carrying out the process.

Any alkyl ester residue is preferably Cl-4
Alkinope more preferably straight chain C + -4 alkyl,
Particularly n-butinoben, n-propyl, ethyl or methyl, with ethyl and methyl being most preferred.

Chlorination of the starting acrylic acid and/or crotonic ester is easily carried out without solvent (and water) intervention. The chlorine addition reaction is preferably carried out in the presence of a chlorination catalyst,
This is done by adding gaseous chlorine directly. Preferably, the catalyst is an N-substituted amide of a carboxylic acid, advantageously a Cl-5 aliphatic carboxylic acid, preferably a C1-4 aliphatic carboxylic acid, especially acetic acid or formic acid. The amide residue may have 1 or 2 C+ to 12 hydrocarbon residues, preferably 1 or 2 C1-4 hydrocarbon residues, especially methyl or ethyl. Particularly preferred as catalyst is dimethylformamide. The chlorination catalyst is usually 0.01 to 5% by weight based on the weight of the ester,
It is preferably used at a concentration of 0.5 to 5% by weight. Chlorination is usually carried out without light intervention at temperatures of 0 to 70<0>C, preferably 15 to 50<0>C. Excess chlorine, e.g.
Although up to 10 mole % chlorine can be used,
A stoichiometric amount of chlorine will be sufficient to obtain the optimum degree of chlorination in a closed vessel.

Then directly, without isolation, the obtained 2,3-
Dichloropropionic acid and/or butyric acid alkyl esters are dehydrochlorinated and saponified in the presence of aqueous base.

A suitable base is NaOH.

Includes alkali metal hydroxides such as KOH or LiOH or ammonium hydroxide, with ammonium hydroxide and especially sodium hydroxide being preferred.

Dehydrochlorination and saponification are carried out at most the same time, preferably at least 10 minutes.
℃260℃, preferably 0-60℃, especially 20-40℃
It is carried out at a temperature of °C. The base is usually added in an amount and at a rate such that alkaline conditions are maintained throughout the period of dehydrochlorination and saponification. The base can be added in stoichiometric amounts or in excess, for example in amounts of up to 70 mol % per mole of ester, in portions or continuously. Dehydrochlorination and saponification can be carried out in an aqueous medium containing inert salts. When sodium monohydroxide is used as the base, it is advantageous to add an alkali metal halide, preferably sodium chloride, to the reaction mixture, and a concentrated brine such as a 20-30% sodium chloride solution is added to the reaction mixture. is preferable. The concentration of 2,3-dichloroester in the aqueous reaction mixture may advantageously be from 5 to 70% by weight, preferably from 5 to 20% by weight, especially from 7 to 15% by weight.

After dehydrochlorination and saponification have been completed, the reaction mixture is advantageously treated with a strong organic or inorganic acid, such as sulfuric acid, hydrochloric acid, phosphoric acid,
or acidified to a pH of less than 7, preferably from 1 to 5, by addition of an aromatic sulfonic acid such as p-toluenesulfonic acid, preferably hydrochloric acid. The temperature is -10~
It may be in the range +60°C, preferably 0-40°C. For the subsequent polymerization step, it will be advantageous to acidify to such an extent that a mixture of the free acid and the corresponding alkali metal salt or ammonium salt is obtained. The acid should be added in an amount sufficient to neutralize the excess base and convert only a portion of the α-lytetraacrylic acid and/or α-chlorocrotonate to the corresponding free acid form. . Generally, 0.4
Preferably 0.4 to 1 mole of acid (preferably hydrochloric acid) is added per mole of alkyl ester to ~2 mono.

Depending on the pH conditions, α-chloroacrylic acid and/or α-chlorocrotonic acid can be obtained in the free acid form or in the form of a mixture with the salt form.

When it is desired to temporarily store monomeric acids or acid salts in solution without polymerization, polymerization inhibitors,
It will usually be advantageous to add hydroquinone or hydroquinone monomethyl ether. Inhibitors are usually added in amounts of 30 to tooppm based on the weight of monomer.

Polymerization of α7-chloroacrylic acid or α-chlorocrotonic acid (or copolymerization in the case of a mixture of both acids) is usually carried out under acidic conditions, preferably in the range of 1 to 5, more preferably 1 to 3.5. is carried out in the same aqueous medium in which the monomeric acid was prepared at a pH of . Catalysts commonly used for polymerization reactions, such as azo compounds, especially 4.4'
-Azo-bis-(4-cyanopentanoic acid) or azo-
bis-1so-butyronitrile, peroxy compounds such as cumene hydroperoxide, sodium perborate, hydrogen peroxide or potassium peroxydisulfate, or peroxy compounds such as those mentioned above as oxidizing agents and as reducing agents such as dithionite. A redox system containing sodium or hydrogen sulfite is added to the reaction medium. Among the above catalysts, per-compounds, especially hydrogen peroxide, are preferred, hydrogen peroxide can be used as such or in the form of H2O2 generating compounds, such as potassium peroxide, and hydrogen peroxide can be directly preferred use. The catalyst is
In usual amounts, for example at least 0 per mole of monomer
．． 0001 mol can be used.

If the catalyst is an azo compound, it is 0.0001 to 0.005 mol per mol of monomer, more preferably
Preferably, it is used in an amount of 0.0002 to 0.003 mol. If the catalyst is a par compound (especially H2O2), it is preferably used in an amount of 0.005 to 3.25 mol per mole of monomer. Average molecular weight M of sodium salt
w is 2000 to 10000 (preferably 3000 to 1
For the production of polymers in the range 0.000 to 8000, more preferably from 4000 to 8000, the Parr catalyst preferably contains from 0.1 to 3.25 moles, more preferably from 0.2 to 3 moles, per mole of monomer. used in quantity.

Polymerization (or copolymerization) is usually carried out at a temperature of room temperature or higher and 150° C. or lower, depending on the catalyst used. If a redox system is used as a catalyst, the polymerization will be at least 2
It can be carried out at a temperature of 0 °C, in the presence of a peroxy compound the polymerization can be carried out at a temperature of at least 40 °C, preferably at least 50 °C, and if an azo compound is used as catalyst the polymerization can be carried out at a temperature of at least 60 °C. ,
Preferably it is carried out at a temperature of at least 70°C. If desired, polymerization can be carried out in an autoclave. The preferred temperature range is 80 to 105°C when an azo compound is used as a polymerization catalyst, and 7 to 105°C when a peroxy compound is used as a polymerization catalyst.
0 to 90°C, especially below 80°C.

Depending on the desired molecular weight, a chain transfer agent,
For example, it may be advantageous to add catalytic amounts of thioglycolic acid, thioglycolic acid metinope SH2, n-C2-4 mercaptans or water-soluble alcohols.

Replacement of alpha-chlorine atoms in the polymer by hydroxy groups can generally be carried out in the same temperature range and similar pH conditions as described above for polymerization. Preferably, the chlorohydrolysis is carried out almost simultaneously with the polymerization. α
- As soon as the chlorine atom is replaced by a hydroxyl, lactonization takes place and polylactones are formed almost simultaneously. Lactonization can be partial or total.

The resulting polylactone is insoluble in water and exists as a solid in the aqueous reaction medium. These can be isolated by known methods, for example by filtration or centrifugation and washing with water. If desired, the polylactone can be prepared with an aqueous base, such as an alkali metal hydroxide, such as Li0HXNaOH.
Or KOH.

Ammonium hydroxide or amines, such as tri(β
-hydroxy-02-3alkyl)amines, preferably the corresponding poly-(α-
(hydroxycarboxylic acid) salt. poly
The (alpha-hydroxycarboxylic acid) salts can also be obtained directly, without intermediate isolation of the polylactone, by adding an aqueous base to the polylactone-containing reaction medium.

The resulting polymers, whether in lactone or salt form, have a wide range of molecular weights.

Advantageously, they range from 1,000 to 1,000,000, preferably from 1,000 to 500,000, especially from 2,000 to 1,400
00 (relative to the sodium salt). Polylactones and the corresponding poly-(α-hydroxycarboxylic acid) salts, especially poly-(α-hydroxyacrylic acid) salts, are known compounds. These are used, for example, as sequestrants, auxiliaries in alkaline peroxy bleaches, or dispersants.

The process of the invention provides that polylactones are prepared directly from alkyl acrylates and/or alkyl protonates in high yields without intermediate isolation steps, and
It is particularly advantageous in that it can be carried out in one vessel (as a one-pot process).

According to a preferred embodiment of the invention, polylactones of poly-(α-hydroxyacrylic acid) or alkali metal poly-(α-hydroxyacrylates) are preferred.

The following examples serve to further illustrate the invention. Unless otherwise indicated, parts are by weight and temperatures are in degrees Celsius.

86 g (1 mole) of methyl acrylate and 2,58
g of dimethylformamide is placed in a three-turn flask at room temperature. After purging the flask with nitrogen, 71 g of chlorine are passed into the mixture without light intervention at room temperature and at such a rate that the temperature does not exceed 30°.

Methyl 2,3-dichloropropionate is obtained with a purity of more than 94%.

A solution of 50 g of sodium hydroxide in 285 ml of water,
Add dropwise to the obtained methyl 2,3-dichloropropionate over a period of 235 hours at such a rate that the temperature is maintained between 15 and 0°. After a further 2.5 hours, a solution of 50 g of sodium hydroxide in 70 ml of water is added dropwise to the reaction mixture at such a rate that the temperature does not exceed 0°. The resulting mixture is then stirred at 0° for 5 hours and left overnight at 0-15°. The obtained sodium α-tetraroacrylate is modified to α-chloroacrylic acid at 0° by adding 100 g of 36% hydrochloric acid. The reaction mixture is 2,5
It has a pH of

Without isolating the α-chloroacrylic acid, the reaction mixture was heated to 95-98° and 0.34 g in 5Qml water
Add a few drops of 2N hydroxide to the solution of 4.4'-azobis=(4-cyanopencunic acid) with stirring) IJ
Add dropwise over 15 hours. This causes the solid to precipitate. The reaction is then further heated to boiling and refluxed for 3 hours. After cooling, the reaction mixture is filtered and the filter cake is washed with water and then dried. In this way, poly-(α-
81.4 g of a polylactone (hydroxyacrylic acid) are obtained with a yield of 90% according to microanalysis.

Example 2 Example 1 was repeated with the following changes.

440 to the obtained methyl 2,3-dichloropropionate.
g of 26% sulfur chloride aqueous solution is added. 0°
After cooling to , 163.2 g of 25% ammonium hydroxide solution (calculated as NHs) are added dropwise in 1 hour at such a rate that the temperature is kept below 0°C. Then,
The reaction mixture is stirred at 0° for 5 hours and then left at 0-15° overnight.

The mixture was then further processed as described in Example 1,
Obtain polylactone.

Example 3 258 g of methyl acrylate are placed in a 750 ml four-way flask and reacted with 7.7 g of dimethylformamide. After purging the flask with nitrogen, 213 g of chlorine
Pass through the mixture without light intervention. Temperature from 20° to 4
Increase from 0 to 45°, but not above 45°. Once the chlorine addition is complete, stir the mixture to an additional 45°
The reaction is completed by stirring for 30 minutes at 50° C. and then heated to 50° and evacuated until no more chlorine is generated in the medium. 477 g of 2, corresponding to 99.6% of the theoretical yield
．． Methyl 3-dichloropropionate is obtained with a purity of more than 97%.

159 g of the obtained methyl 2,3-dichloropropionate and 239 g of water are placed in a four-piece flask. Under stirring, 266 g of 30% sodium hydroxide solution was added to 40
It is added dropwise over a period of 3 hours at a temperature not exceeding . next,
A clear solution of sodium α-chloroacrylate is obtained, to which a further 50 g of 38% HCI solution are added dropwise over a period of about 60 minutes at a temperature not exceeding 40°. The pH obtained is 2.5. heating the reaction mixture to 95°;
A solution of 0.113 g of 4,4'-azo-bis-(4-cyanopentanonic acid) in 20 ml of water is then added dropwise over the course of 1 hour. Once the catalyst addition was complete, the reaction mixture was heated to 95° for an additional hour, and after cooling to room temperature, the resulting precipitate was filtered, washed free of chlorine, and heated to 50°.
Dry in vacuum. During the addition of the catalyst, the ester is sequentially subjected to polymerization, chlorohytrolysis and lactonization. At the end of the reaction, the precipitation of the polylactone of poly-(alpha-hydroxyacrylic acid) is substantially complete.

White powder with a carbon content of approximately 45%. Yield 73.5
g0 Example 4 The operation of Example 3 was repeated, but now 0.1
13 g of 4,4'-azo-bis-(4-cyanopencunic acid) is replaced by 1 g of 37% hydrogen peroxide. The yield, C analysis and characteristics of the polylactone obtained correspond to that of the polymer of Example 3.

Example 5 The procedure of Example 4 is repeated, but now the polymerization is carried out at 75° instead of 95° in the presence of 5 g of 40% by volume hydrogen peroxide and the reaction mixture is further treated at 75° for 1 hour to react. complete. The yield, C analysis and characteristics of the polylactone obtained are similar to that of the polymer of Example 4.

Example 6 The procedure of Example 5 is repeated, but now 0.003 g of thioglycolic acid is added to the reaction mixture before the addition of hydrogen peroxide. The yield, C analysis and characteristics of the polylactone obtained are similar to that of the polymer of Example 5.

Example 7 In a 2,5β flask equipped with a stirrer and a thermometer, 25
Charge 8 g of methyl acrylate and add 7.7 g of dimethylformamide. 213 g of chlorine are then passed through the mixture without the presence of light at such a rate that the temperature of the reaction mixture does not exceed 40°. Once the chlorination reaction is complete,
Excess chlorine is removed in vacuo and the product obtained is stirred with 503 g of deionized water until a good distribution of the organic phase in the water is obtained. Then 800 g of 30% sodium hydroxide solution are added dropwise. The temperature is raised to 20-40° and then maintained at 40° by cooling.

The addition is complete after 2.5 hours. The temperature is kept at 40° for a further 30 minutes and then 180 g of 30% hydrochloric acid solution are added dropwise to the sodium α-chloroacrylate solution obtained within 30 minutes at this temperature.

After addition of acid, the pH of the reaction solution is approximately 2.5.

75 g of 35% hydrogen peroxide are then added within 5 minutes, which causes the reaction mixture to become cloudy. The reaction mixture was then heated continuously to raise the temperature from 40° to 75° within 1 hour and to 75°C.
Stir for a further 3 hours at °C and then cool to room temperature. The resulting polylactone suspension is filtered with suction and washed with 9000 g of deionized water. A beige bicolored filter cake with a solids content of 27% is obtained. Dry the filter cake at 110°.

Example 8 The procedure of Example 7 is repeated to prepare a polylactone suspension. The resulting polylactone suspension is not filtered and is reacted directly with 450 g of 30% hydroxide solution at 50-60°. To the resulting slightly cloudy brownish solution, 7 g of 35% hydrogen peroxide are added and the entire mixture is stirred at 60° for 30 minutes.

The resulting sodium poly-(α-hydroxyacrylate) has a molecular weight MW of 4865.

Claims (1)

[Claims] 1. An alkyl acrylate or an alkyl crotonate or a mixture thereof is chlorinated to produce the corresponding alkyl 2,3-dichloropropionic acid ester or alkyl 2,3-dichlorobutyric acid ester or a mixture thereof; 2,3-dichloropropionic acid alkyl ester or 2,3-dichlorobutyric acid alkyl ester or a mixture thereof is treated with an aqueous base to dehydrochloride and convert to the corresponding salt, followed by acidification and polymerization, poly(alpha-hydroxyacrylic acid and/or crotonic acid) to polylactones under acidic conditions, but carrying out the process without isolating the intermediate products. / or crotonic acid) production method. 2. The process according to claim 1, wherein the acrylic acid alkyl ester or crotonic acid alkyl ester or a mixture thereof is chlorinated in the presence of an N-substituted carboxylic acid amide used as a chlorination catalyst. 3. Dehydrochlorination and conversion to the salt form are carried out in the presence of an aqueous solution of alkali metal hydroxide or ammonium hydroxide;
The method according to claim 1. 4. The process according to claim 1, wherein the acidification is carried out by adding a strong organic or inorganic acid to obtain a pH of 1 to 5. 5. The process according to any one of claims 1 to 4, wherein the polylactone obtained is hydrolyzed to the corresponding poly-(α-hydroxycarboxylate) with an aqueous base. 6. The method of claim 5, wherein the polylactone is hydrolyzed without isolating it from the mother liquor.