JPH0571041B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing polylactone (hereinafter referred to as PLAC) corresponding to poly-α-hydroxyacrylic acid. PLAC is industrially important as a precursor of poly-alpha-hydroxy sodium acrylate (hereinafter referred to as PHAS), which is useful as a sequestering agent and a builder for detergents. (Prior Art) PLAC was first synthesized by CS Marvel et al. Marvel et al. irradiated α-chloroacrylic acid in an organic solvent with light from a mercury lamp to form a solid polyester.
by precipitating and isolating α-chloroacrylic acid, dissolving it in water, and boiling it.
It was shown that PLAC can be obtained. [J.Amer.Chem.
Soc., Vol. 62, pp. 3495-3498 (1940)]. In addition, Example 1 of Belgian Patent No. 796531 is a completed version of this method, in which α-chloroacrylic acid is polymerized by heating in benzene in the presence of benzoyl peroxide. -α-chloroacrylic acid is separated, dissolved in water and heated, and the precipitate is separated and dried to obtain PLAC. The method of polymerizing α-halogenoacrylic acid in these organic solvents and further heating the resulting poly-α-halogenoacrylic acid in water to obtain PLAC involves a large number of steps, uses organic solvents, and requires equipment. The drawback is that the cost is high and the resulting product is expensive. Therefore, in recent years, a method has been proposed in which PLAC is obtained by polymerizing α-halogenoacrylic acid in water and lactonizing it by heating, which has become the basic method for PLAC synthesis. For example, patent publication No. 57-39249 by Solvay
According to
Contacting chloroacrylic acid with a polymerization catalyst in water
A method to obtain PLAC has been proposed. Also, similarly
According to patent publication No. 54-5839 by Solvay,
An aqueous solution of α,β-dichloropropionic acid was heated to 100°C.
We have proposed a method in which α-chloroacrylic acid is obtained by heating to the above temperature, and a polymerization catalyst is applied to the aqueous solution to obtain PLAC. Also, patent publication No. 57-27882 by Hoechst
Then, by treating an aqueous solution of α-chloroacrylic acid with a polymerization catalyst that has a radical-forming action, and heating the resulting poly-α-chloroacrylic acid to a temperature of 80 to 100°C for more than 1 hour without isolating it. Tsute
A method to obtain PLAC is proposed. However, in these methods, α,
In order to cause the dehydrochlorination reaction of β-dichloropropionic acid, special equipment such as an autoclave or a special catalyst bed is required, and various instrumentation devices are required to control the reaction temperature etc. Therefore, when constructing a plant, a large amount of cost is required, resulting in a disadvantage that the product becomes expensive. Furthermore, the yield is only about 70% based on α,β-dichloropropionic acid, which is not satisfactory.Furthermore, the remaining 30% flows out into the waste liquid, which places a great burden on waste liquid treatment. It also has some drawbacks. Furthermore, in order to obtain the raw material α,β-dichloropropionic acid, chlorine is generally added to acrylic acid, and there are two methods for this: photochlorination and the use of a catalyst. When carrying out the photochlorination method industrially, special lamps and safety equipment are required, and it also has disadvantages such as trichlor compounds such as 2,3,3-trichloropropionic acid being produced as by-products. ing. In addition, chlorination methods using catalysts also
In the first place, acrylic acid is a substance that polymerizes extremely easily, so polymerization progresses during the reaction and efficiently converts α and β.
-Dichloropropionic acid is difficult to obtain. In this way, by the above-mentioned conventional technology,
When attempting to produce PLAC, various problems arise even in the step of obtaining α,β-dichloropropionic acid, which is the raw material. On the other hand, German Patent Publication No. 2061584 by Henkel describes a method for producing water-soluble salts of poly-α-oxyacrylic acid, in which α,β-dihalogenoacrylic acid or its ester is boiled for a long time together with a preparation with basic action, during which an intermediate product of unknown structure is precipitated, which is a lactone containing halogen residues, which is separated, washed, and subsequently Dissolve in hot caustic soda. Sodium poly-α-oxyacrylate is precipitated by pouring the cooled solution into methanol. However, Henkel's method has the disadvantage that a good yield can only be achieved when expensive α,β-dibromopropionic acid is used.
When cheap α,β-dichloropropionic acid is used, there is a major problem in that PLAC cannot be obtained in good yield. Also, Example 3 of Henkel's patent publication
So, methyl α,β-dibromopropionate 1.0
A water-insoluble intermediate was obtained by reacting 1.15 moles of sodium acetate with 1.15 moles of sodium acetate and boiling it in water. Under the conditions of action, the substance produced is mainly α-halogenoacrylic acid ester, and if no polymerization initiator is present, even if heated, α-halogenoacrylic acid ester will be dispersed in water as an oil. PLAC cannot be obtained. Furthermore, the polymer that is produced even when a polymerization initiator is applied is poly-α-halogenoacrylic acid ester, which is insoluble in cold NaOH water and has a completely different structure from PLAC. . Therefore, it is not possible to obtain PLAC with this method. Furthermore, for the same reason, it is impossible to produce PLAC even if methyl α,β-dichloropropionate and sodium acetate are allowed to interact with each other. As mentioned above, when attempting to produce PLAC using conventional techniques, there are problems such as requiring special equipment, problems with yield, or expensive raw materials. There are various problems. (Problems to be Solved by the Invention) The object of the present invention is to provide a method for obtaining PLAC in a high yield with a simple device that does not require any special equipment and is inexpensive and easy to obtain or produce raw materials. The goal is to provide the following. (Means for Solving the Problems) The present inventors have completed research on manufacturing PLAC for many years and have completed the present invention. That is, the present invention provides: (a) α,β-dichloropropionic acid ester 1.0
A basic substance (n indicates the valence of the basic substance) of 1.9/n to 3.0/n times the mole of the basic substance is reacted in water to obtain an aqueous solution of the corresponding α-chloroacrylate, and then, (b) The aqueous solution of α-chloroacrylate obtained in step (a) is treated with 0.02 to 3.0 equivalents of acid per 1.0 equivalent of the basic substance used in step (a), and the polymerization catalyst is Polylactone (PLAC) corresponding to poly-α-hydroxyacrylic acid, which is characterized by being heated to a temperature of 40 to 200°C in the presence of
This is a manufacturing method. The α,β-dichloropropionic acid ester that is the object of the present invention is an ester of α,β-dichloropropionic acid having a lower alcohol component having 1 to 3 carbon atoms. Methyl is a typical example. These α,β-dichloropropionate esters can be easily obtained by reacting the corresponding acrylic esters with chlorine. For example, by blowing chlorine into metal acrylate in methanol at a temperature below 40°C, methyl α,β-dichloropropionate can be obtained in a yield of 85% or more. (J.
Org.Chem. vol. 62, p. 3495, 1940) In addition, according to the method described in the patent specification pending by the present inventors, by reacting acrylic acid ester with chlorine in the presence of a specific nitrogen-containing compound, It is possible to obtain α,β-dichloropropionic acid ester in high yield. (Special application No. 61-280778
(Japanese Unexamined Patent Publication No. 134025/1983)) The basic substances used in the present invention include:
Sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide,
Although sodium acetate, ammonia, lower alkylamine, etc. can be used, it is common to use sodium hydroxide. The molar ratio of the basic substance to α,β-dichloropropionate is 1.9/n~
It can be used in a range of 3.0/n times, but preferably 2.0/n to 2.4/n times by mole. When using a monovalent base, the molar ratio is 1.9~
If you use 3.0 times the amount of base, or if you use a divalent base, you will use 0.95 to 1.5 times the amount of base.
In the following explanation, for convenience, a monovalent base (n
=1) will be explained as an example. If the mole is 1.9 times or less, the intermediate obtained in step (a) will mainly be α-chloroacrylic acid ester, and this will polymerize, so the obtained polymer will be
It is mainly composed of poly-α-chloroacrylic acid ester rather than PLAC, and this
Insoluble in NaOH. Conversely, using more than 3.0 times the amount of base also causes a decrease in yield. As described above, the molar ratio of the basic substance used in the present invention has an extremely important meaning. The concentration of the basic substance can be applied in a wide range, but it is best to use it in the range of 10 to 30%. The temperature at which the α,β-dichloropropionic acid ester and the aqueous base solution are allowed to react may be in the range of 0°C to 80°C, but preferably controlled within the range of 20 to 40°C. Regarding the treatment of the alcohol component produced as a by-product in step (a), (1) proceed directly to step (b) and remove it by washing the PLAC after polymerization. (2) Method of distilling off before polymerization. (3) There are three methods of distilling off the alcohol component at the same time as polymerization. Although any method can be used, it is better to distill off the alcohol component before or during polymerization to remove NaCl remaining as an impurity in the product PLAC. This is a desirable method because the content can be reduced. In addition, from the perspective of waste liquid treatment,
It is preferable to distill off the alcohol component before or during the polymerization. When carrying out method (2), the pH of the solution can be adjusted within a wide range, but α-chloroacrylate will decompose under strong alkalinity, so it is better to neutralize it if necessary. . The best pH range is 5.0 to 8.0. Although distillation can be carried out under normal pressure, it is more advantageous to carry out the distillation under reduced pressure. Method (3) is an industrially advantageous method that saves time and energy required for the entire reaction process because the alcohol content is distilled off at the same time as the polymerization. The acids used in step (b) include hydrochloric acid, sulfuric acid,
Inorganic acids such as perchloric acid and nitric acid, and organic acids such as acetic acid, propionic acid, and formic acid can be used, but from the viewpoint of wastewater problems, it is more advantageous to use inorganic acids, and it is especially preferable to use hydrochloric acid. Common. The acid used in step (b) may be used in its entirety before polymerization, or may be added dropwise one after another during polymerization. Furthermore, any combination of methods for distilling off alcohol components is possible. The acid used in step (b) is essential to carry out the present invention, and it is necessary to use 0.02 to 3.0 equivalents per 1.0 equivalent of the base used in step (a).
Preferably, it is 0.05 to 1.0 equivalent. If less than 0.02 equivalent of acid is used, or if no acid is used at all, the polymerization system becomes a jelly, and either no PLAC is obtained, or even if PLAC is obtained, the filterability is extremely poor. Catalysts used in the polymerization process include organic peroxides such as benzoyl peroxide and cumyl peroxide; inorganic peroxides such as hydrogen peroxide, sodium perborate, potassium persulfate, ammonium persulfate, and sodium persulfate; redox. Initiators and polymerization catalysts with radical action such as diazo compounds can be used. The polymerization temperature can range from 40 to 200°C, but preferably from 70 to 110°C. One method for polymerization is to add a predetermined amount of acid to the α-chloroacrylate aqueous solution obtained in step (a) as it is, and polymerize by heating in the presence of a polymerization catalyst. . In addition, α-
A method of heating while adding an aqueous solution of sodium chloroacrylate is also possible. The base used in step (a) is used in a molar ratio of 1.9 to 3.0 times the amount of α,β-dichloropropionic acid ester, although it is common to use the entire amount in one stage. It is also possible to use it.
In particular, in step 1, 0.8 to 1.2 times the mole of base is first applied to α,β-dichloropropionic acid ester to obtain α-chloroacrylic acid ester through dehydrochlorination reaction, After separating the acid ester layer and the aqueous layer, if a method is used in which the remaining 0.7 to 2.2 times the mole of base is applied to the α-chloroacrylic acid ester in the second step, by-products are removed in the first step. Since the NaCl content can be separated and disposed of in the aqueous layer, from the second stage onwards,
It has the great advantage of being able to reduce the NaCl content, thereby making it possible to obtain more concentrated α-chloroacrylate, and increasing the volumetric efficiency of the device. Also, in the product
It is also advantageous to reduce the NaCl content. (Function) In the reaction between α,β-dichloropropionate and a basic substance, when the molar ratio is around 1:1, only the dehydrochlorination reaction occurs preferentially, and α
- gives chloroacrylic acid ester. Therefore, when the molar ratio is around 1:1, it is difficult to cause hydrolysis of the ester, and it is essential to use a base with a molar ratio of 1.9 times or more. By using 1.9 times the mole or more of the base, α-chloroacrylate can be obtained in high yield. If we take advantage of the fact that the dehydrochlorination reaction occurs preferentially at a molar ratio of around 1:1, we can first obtain α-chloroacrylic acid ester in the first step, separate the oil and water layers, and remove NaCl from the system. It will be possible to release it to As a result, NaCl in α-chloroacrylate aqueous solution
The concentration of α-chloroacrylate can be lowered, and the concentration of α-chloroacrylate can be increased. On the other hand, when obtaining PLAC through polymerization, simply applying a polymerization catalyst to the aqueous solution of α-chloroacrylate obtained in step (a) and heating it will result in the polymerization solution becoming jelly-like. , in order to obtain solid PLAC, the final pH must be at least 2.5 or less, therefore, the base used in step (a)
It is essential to polymerize using at least 0.02 equivalents of acid per 1.0 equivalents. (Effects of the invention) According to the method of the present invention, it is possible to use α,β-dichloropropionic acid ester, which is available at low cost, as a raw material, and it is possible to perform a very general reaction without using special equipment. equipment and high yield.
It is possible to obtain PLAC. (Example) Examples of the present invention are shown below. Examples 1 to 13 and Comparative Examples 1 to 4 A predetermined amount of 10% aqueous base solution was placed in a 500 ml four-necked flask equipped with a stirrer and a thermometer, and α, β
- 0.5 mol of dichloropropionic acid ester is added dropwise at a reaction temperature of 30 to 40°C and stirred for 1 hour. This solution is treated by any one of the following methods A, B, and C to obtain an α-chloroacrylate aqueous solution. Method A: The alcohol component is distilled off at a temperature of 30 to 60°C under a reduced pressure of 20 mmHg. Method B: Distill at normal pressure. Method C: Proceed to the next step without distilling off the alcohol component. Next, polymerization is performed by one of methods D and E described below. For polymerization, in each case 5
% potassium persulfate aqueous solution. Method D: Add a predetermined amount of hydrochloric acid, temperature 90-95℃,
Polymerize under conditions of 4 hours. Method E: Add a predetermined amount of hydrochloric acid and polymerize for 4 hours at a temperature of 90-104°C while distilling. After the polymerization is completed, it is cooled, filtered under reduced pressure, and washed with 300 ml of pure water. The obtained water-containing cake was heated to 105℃.
It was dried for 4 hours to obtain PLAC. When the structure of PXAC obtained in the example was examined by infrared spectrum, it matched well with the spectrum of PLAC obtained by the method described in Solvay's patent application "Japanese Patent Publication No. 54-5839", indicating that the structure is confirmed. In addition, all of the PLACs obtained in the examples contain almost no Cl in their skeletons (0.5% or less) and quickly dissolve in cold NaOH water. Table 1 summarizes the results obtained. Note that residual alcohol was analyzed by gas chromatography. The yield of PLAC is calculated based on a molecular weight unit of 76, which is obtained by subtracting the NaCl content to obtain the pure PLAC content, and assuming that 2/3 is lactonized. Example 14 200 g of 10% NaOH (0.50 mol as NaOH) in a 300 ml four-necked flask equipped with a stirrer and a thermometer.
and methyl α,β-dichloropropionate.
78.5 g (0.5 mol) was added dropwise at 30°C. 30 minutes later,
Separate the oil layer and water layer, put the oil layer into a reactor, and heat for 20 minutes.
% NaOH aqueous solution 110g (0.55 mol as NaOH)
Add and dissolve at 30℃. The methanol content was distilled off under reduced pressure of 20 mmHg to obtain 120 g of sodium α-chloroacrylate solution. The remaining methanol concentration is 0.6%, and the methanol removal rate is 95.5
It was %. Add 100g of water to this solution, 35%
Add 10.0g of HCl and heat to 90-95℃ for 5 minutes.
% potassium persulfate aqueous solution was added dropwise. 4hr
After keeping the temperature at 90-95℃ for a while, the same procedure as in Example 1 was carried out.
Obtained PLAC37.9. NaCl content is 0.01%, pure
The yield of PLAC was 37.9 g, with a yield of 99.7%. Comparative Example 5 (Method in Henkel's patent specification) 82.0 g of sodium acetate (anhydrous) was placed in a 500 ml four-necked flask equipped with a stirrer, thermometer, and cooler.
(1.0 mol), add 250 g of water and dissolve.
α,β-Methyl dichloropropionate 137g
(0.87 mol) was added and heated to boiling with stirring. (The molar ratio was 1:1.15.) Although heating and stirring were continued for 3 hours, no solid matter appeared, and when stirring was stopped, the mixture was separated into an oil layer and an aqueous layer. When the two layers were analyzed by HPLC, the composition was as follows.

[Table] Comparative Example 6 (Henkel patent example method) In a 2-volume flask, 429 g of methyl α,β-dibromopropionate (1.74 mol) and 500 ml of water,
Add 272 g (2.0 mol) of sodium acetate trihydrate and bring to a boil. (The molar ratio is 1:1.15.) The boiling point of the reaction mixture was 102°C, and although it was boiled for 4 hours, no solid matter appeared, and when stirring was stopped, it separated into an oil layer and an aqueous layer. did. The composition of the two layers was as follows.

[Table] Comparative Example 7 (Method in Henkel's patent specification) A chemical was reacted with exactly the same preparation as in Comparative Example 5,
While applying 13.5g of 5% potassium persulfate aqueous solution,
Stir at boiling for 3 hours. Insoluble solid lumps appeared midway through the process and also adhered to the stirring blade and thermometer. After cooling, the lump material was taken out and dried at 105°C for 4 hours. The yield was 85.0g. The infrared spectrum of this substance was different from that of PLAC obtained by the method described in the literature (Japanese Patent Publication No. 54-5839), and the characteristic peak was ester around 1750 cm ^-1 . There is a peak that appears to be carbonyl. Furthermore, when we performed elemental analysis of this substance, we found that
It was found that it had 28.7% Cl. Furthermore, this material is different from PLAC in that it does not dissolve in cold NaOH aqueous solution. Considering the above, it is estimated that this lumpy material is mainly composed of poly-α-methyl chloroacrylate.

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Claims (1)

[Claims] 1 (a) α,β-dichloropropionate ester
1.0 mole to 1.9/n to 3.0/n times the mole of a basic substance (n indicates the valence of the basic substance) is reacted in water to obtain an aqueous solution of the corresponding α-chloroacrylate, (b) 0.02 to 3.0 equivalents of acid per 1.0 equivalent of the basic substance used in step (a) are allowed to act on the aqueous solution of α-chloroacrylate obtained in step (a), A method for producing a polylactone corresponding to poly-α-hydroxyacrylic acid, which is characterized by heating to a temperature of 40 to 200°C in the presence of a polymerization catalyst. 2. The method according to claim 1, wherein the process proceeds to step (b) after distilling off the alcohol component produced as a by-product in step (a). 3. The method according to claim 1, characterized in that the alcohol component produced as a by-product in step (a) is distilled off simultaneously with the polymerization in step (b). 4 In the step (a), 1.9/n used per 1.0 mol of α,β-dichloropropionic acid ester
~3.0/n times the mole of basic substances (n indicates the valence of the basic substance), in the first step,
0.8/n to 1.2/n times the molar basic substance to α, β
The remaining 0.7% of
2. The method according to claim 1, characterized in that n to 2.2/n times the molar amount of the basic substance is allowed to act on the α-chloroacrylic acid ester obtained in the first step.