JPS6241662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for industrially safe and advantageous production of high quality 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate in high yield. Specifically, the present invention involves an esterification reaction between acrylic acid or methacrylic acid and an alkylene oxide having 2 to 4 carbon atoms using an organic carboxylic acid iron salt as a catalyst, and then distilling the resulting reaction product liquid to obtain high-quality 2-hydroxy. The present invention relates to a method for obtaining alkyl acrylate or 2-hydroxyalkyl methacrylate in high yield. 2-hydroxyalkyl acrylate or 2
-Hydroxyalkyl methacrylate [hereinafter 2-
Hydroxyalkyl (meth)acrylate. ] has traditionally been acrylic acid or methacrylic acid [hereinafter referred to as (meth)acrylic acid. ] and alkylene oxide, and in this case, Lewis acid compounds such as ferric chloride, iron compounds such as ferric organic carboxylates, chromium compounds, titanium compounds, aluminum chloride, etc., or bases are used as catalysts. system compounds such as tertiary amines,
Quaternary aluminum salts, other phosphonium salts, organic sulfur compounds, iron hydroxides, etc. are used. Among the above-mentioned compounds, iron compounds have better activity and selectivity for the reaction than other catalysts. However, among these iron compounds, ferric chloride corrodes equipment, discolors products, and produces chloride by-products, and iron hydroxide causes scale in distillers due to the precipitation of iron compounds during distillation. It has disadvantages such as generation, and cannot be used industrially without inconvenience. On the other hand, when 2-hydroxyalkyl (meth)acrylate is produced using a ferric salt of an organic carboxylic acid such as acrylic acid, methacrylic acid, benzoic acid, phthalic acid, or salicylic acid as a catalyst, alkylene glycol di(meth)acrylate ( (hereinafter referred to as diester), there is no by-product, and the product is highly pure and high quality without coloring.Moreover, even if it is distilled as it is without separating the catalyst from the reaction solution, there is no precipitation of iron compounds and no scaling occurs in the distillation pot. No generation problems arise. However, during the distillation of this reaction solution, it has been found that as the high-boiling point components become concentrated, especially in the latter half of the distillation, the viscosity of the remaining liquid in the can increases rapidly, and gelation gradually occurs, making distillation impossible. is suppressed, and the overall yield is also suppressed to a considerably low level. Moreover, it is known that if this can residual liquid is taken out of the system and left to stand, popcorn polymerization will occur. The present inventors have solved the above-mentioned difficulties that arise when producing 2-hydroxyalkyl (meth)acrylate by reacting (meth)acrylic acid and alkylene oxide as a catalyst in the presence of a ferric salt of an organic carboxylic acid. This paper explores a method to overcome these problems and obtain high-yield, high-quality 2-hydroxyalkyl (meth)acrylate. The rapid increase in viscosity and gelation of the bottom liquor that occur during the purification distillation process are not caused by the polymerization of the bottom liquor, but rather due to the organic carboxylic acid iron and 2-hydroxyalkyl (meth)acrylate that are the catalysts for the esterification reaction. It has also been reported that this is due to the formation of a complex complex salt consisting of There is a risk that undesirable reactions may occur and cause impurities to be mixed into the product.On the other hand, if water is added and distilled as is, water will distill out as a light boiling point product in the normal purification distillation process under reduced pressure. During distillation, they cannot coexist in the bottom liquid, and no effect on the decomposition of complex salts can be expected. The present inventors investigated the above esterification reaction, and after adding water, the complex salt is immediately decomposed, and further heat treatment is performed under conditions where water can coexist, and then the water is combined with the remaining alkylene oxide in the initial distillation cut (usually They discovered a method for producing high-quality 2-hydroxyalkyl (meth)acrylate free from impurities as a main fraction by removing the 2-hydroxyalkyl (meth)acrylate by diffusion under reduced pressure, and completed the present invention. That is, the present invention is specified as follows. (1) Purification 2 by esterification reaction of acrylic acid or methacrylic acid and alkylene oxide in the presence of a ferric salt of an organic carboxylic acid and distillation.
-Hydroxyalkyl acrylate or 2-
When producing hydroxyalkyl methacrylate, after the esterification reaction is completed, water is added to the reaction solution in an amount ranging from 0.1 to 5% by weight based on the reaction solution, and further heat treatment is performed at a temperature range of 60 to 100°C for 0.5 to 5 hours. 2-Hydroxyalkyl acrylate or 2-hydroxyalkyl acrylate characterized by distillation after performing
- A method for producing hydroxyalkyl methacrylate. (2) The method according to (1) above, wherein the ferric salt of the organic carboxylic acid is ferric acrylate or ferric methacrylate. The method of the present invention does not cause the above-mentioned phenomenon of rapid increase in the viscosity of the can residual liquid, and the viscosity of the can residual liquid after distilling 2-hydroxyalkyl (meth)acrylate at a high yield is extremely easy to handle. It is surprising that the residual liquid does not lose its fluidity even if it is left at room temperature for a long period of time. The method of the present invention will be explained in detail below. Examples of the alkylene oxide used in the present invention include alkylene oxides having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, etc., and these are equal to or more mole relative to (meth)acrylic acid, preferably 1.05 The addition reaction can be carried out in a range of ~1.2 times the mole. In addition, the organic carboxylic acid iron salts used are:
Ferric salts of organic carboxylic acids such as acrylic acid, methacrylic acid, benzoic acid, phthalic acids, alicylic acid, etc., and ferric salts of acrylic acid and methacrylic acid are particularly preferred. These iron salts are used as raw materials as catalysts for esterification reactions (meth)
0.5-5.0% by weight based on acrylic acid, preferably 1.0
-3.0% by weight. If the esterification reaction is batch type (meta)
Acrylic acid is charged into a reactor, and alkylene oxide is added thereto under stirring. In the case of a continuous method, (meth)acrylic acid is supplied to a tube reactor or the like, and a certain amount of alkylene oxide is added thereto to complete the reaction. The reaction temperature is 40-120℃, preferably 50-100℃,
The reaction is not completed at the end of the addition of alkylene oxide, and the reaction temperature is maintained for a long time, requiring 0.5 to 5 hours for ripening. Water is then mixed into this esterification reaction mixture. Add 0.1 to 5% by weight, preferably 0.5 to 3% by weight, to the reaction mixture at 60 to 100°C, preferably at 60°C.
0.5-5 hours, preferably 1-2 at a temperature of ~90°C
Perform heat treatment for a period of time. The heat treatment is carried out under normal pressure so that the added water sufficiently decomposes the iron salt of the catalyst and stabilizes the decomposition products. The esterification reaction mixture thus heat-treated is rectified under conditions of 1 to 10 mmHg and a temperature of 50 to 100°C. In this rectification operation, it is preferable to perform an initial distillation cut operation (diffusion operation) in order to remove water added during the heat treatment, unreacted alkylene oxide, and the like.
It goes without saying that a stabilizer is added to prevent polymerization in the operations from the esterification reaction to the rectification. The present invention will be explained in more detail with reference to Examples below. Example 1 2-hydroxyethyl methacrylate was produced. Add 600g of methacrylic acid to the reactor,
As a catalyst, ferric methacrylate was added at 2.79% by weight based on methacrylic acid, and as a stabilizer, methquinone was added at 0.015% by weight based on methacrylic acid, and 338g of ethylene oxide was added to the gas at 60°C for 4 hours with stirring. The reaction was carried out by supplying the solution in the form of The ethylene oxide/methacrylic acid ratio was 1.1 (molar ratio). After aging at 60°C for 3 hours, the temperature was raised to 80°C, 1% by weight of water was added to the reaction mixture, and heat treatment was performed for 1 hour under normal pressure. The reaction rate of methacrylic acid was 99.2%. After that, 2.0 g of copper dibutyldithiocarbamate was added to the reaction solution, and
Purification distillation is carried out under reduced pressure of 5 mmHg (absolute pressure) at a bottom liquid temperature of 80 to 90°C, and unreacted ethylene oxide and water are dissipated as an initial distillation cut operation, and then the main fraction is distilled at a distillation rate of 90%. I got it. The viscosity of the residual liquid after distillation was 50 cps/70°C, and it remained fluid even after 30 days. Example 2 After reaction and ripening in the same manner as in Example 1,
Heat treatment was performed. The amount of water added was 0.5% by weight, and the temperature was 70°C and normal pressure for 0.5 hours. Thereafter, rectification was carried out in the same manner as in Example 1, and a main fraction was obtained with a distillation rate of 88%. The viscosity of the remaining liquid after distillation is 60cps/70℃.
It remained liquid even after 30 days. Comparative Examples 1 to 2 Reaction and ripening were carried out under the same conditions as in Example 1, and the heat treatment temperature, time, and amount of water added were shown in Table 1.
Purification distillation was carried out in the same manner as in Example 1, with the changes as shown in Table 1, and the results shown in Table 1 were obtained. Example 3 2-hydroxypropyl acrylate was produced. Put 600g of acrylic acid in a reactor, and add ferric acrylate as a catalyst to the acrylic acid.
2.41% by weight was added, and 0.015% by weight of methoquinone was added as a stabilizer based on acrylic acid, and the mixture was stirred for 70 minutes.
531 g of propylene oxide was supplied in gaseous form for 4 hours at °C to carry out a reaction. The propylene oxide/acrylic acid ratio was 1.1 (molar ratio). Then, after aging at 70℃ for 2 hours (acrylic acid reaction rate was 98.8
%), water was added to the reaction mixture in an amount of 1% by weight at 70°C, and heat treatment was performed under normal pressure for 1 hour. Then, add 1.5 g of copper dimethyldithiocarbamate to the reaction solution.
Purification distillation is carried out at a bottom liquid temperature of 70 to 80°C under reduced pressure of ~5 mmHg (absolute pressure), unreacted propylene oxide and water are dissipated as an initial distillation cut operation, and then the main fraction is reduced to a distillation rate of 90%. It came out. The viscosity of the still residue was 40 cps/70°C, and it remained fluid even after 30 days at room temperature. 【table】

Claims (1)

[Claims] 1. Purified 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate is produced by esterifying acrylic acid or methacrylic acid and alkylene oxide in the presence of a ferric salt of an organic carboxylic acid and distilling the reaction. When manufacturing,
After the esterification reaction is complete, add
adding water in an amount ranging from 0.1 to 5% by weight;
A method for producing 2-hydroxyalkyl acrylate or 2-hydroxyalkyl methacrylate, which comprises carrying out a heat treatment at a temperature range of 60 to 100°C for 0.5 to 5 hours, followed by distillation. 2. The method according to claim 1, wherein the ferric salt of an organic carboxylic acid is ferric acrylate or ferric methacrylate.