JPS6143351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing glycidyl methacrylate, and relates to a novel production method in which a catalyst is synthesized in advance in a reaction system and then a transesterification reaction is carried out.

The present inventors discovered that fatty acid salts such as potassium methacrylate are useful as catalysts in the transesterification reaction between methyl methacrylate and glycide.
No. 42073) was filed first.

However, in the previous application, no consideration was given to obtaining the above catalyst, but in actual industrial production,
In order to obtain the dry powder of the catalyst, complicated work steps such as catalyst synthesis, purification, and drying are required;
It had become a big problem.

The present inventors have studied ways to improve this problem and have arrived at the present invention. That is, in the present invention, a part of methyl methacrylate, which is a raw material for transesterification reaction, is reacted with an alkali metal hydroxide in advance,
This is a method for producing glycidyl methacrylate in which an alkali metal methacrylate salt, which is a transesterification reaction catalyst, is synthesized in a large amount of methyl methacrylate, and glycide is added to this to carry out a transesterification reaction without taking out the reaction product.

Here, potassium hydroxide or sodium hydroxide is used as the alkali metal hydroxide. These alkali metal hydroxides are preferably used in a low moisture state, that is, in a solid state such as flakes or powder.

In the present invention, methyl methacrylate used as a starting material is used in an amount of 2 to 15 times the mole of glycide, preferably 4 to 10 times the mole, and the alkali metal hydroxide is used in an amount of 0.01 to 0.1 mole, preferably 0.01 to 1 mole, per mole of glycide. Use in a range of 0.05 mol. The reaction is carried out in the presence of a known polymerization inhibitor, such as hydroquinone, hydroquinone monomethyl ether, phenothiazine, diphenylamine, etc., and the appropriate amount thereof is 50 to 1500 ppm based on the weight of the total raw materials. The reaction between methyl methacrylate and alkali metal hydroxide is carried out at a reaction temperature of 50°C while introducing a small amount of air into the reaction solution under reduced pressure.
It is preferable to carry out the reaction at ~80°C for about 30 minutes while removing by-product methanol from the reaction system by azeotropy with methyl methacrylate. After the completion of the above reaction, a predetermined amount of glycide is added and transesterification is carried out under the same reaction conditions as above, during which time the molar ratio of methyl methacrylate to glycide in the reaction system is always maintained at 4:1 or more. The reaction is complete in 1.5-4 hours. Next, the reaction mixture is cooled, the catalyst is removed and recovered by filtration, and the filtrate is continuously distilled to obtain glycidyl methacrylate. The glycidyl methacrylate thus obtained has high purity (98%) and high yield (89%).
%), which was as good as the first case using powdered alkali metal methacrylate.
Furthermore, the method of the present invention synthesizes the catalyst in the reaction system and immediately performs the transesterification reaction, which is industrially advantageous because the troublesome steps of synthesizing the catalyst and converting it into a dry powder can be omitted.

Next, the present invention will be explained with examples.

Example 1 A stirring rod, a dropping tank,
A thermometer and a rectification column were attached, and to this was added 600 g (mol) of methyl methacrylate, 0.2 g of hydroquinone monomethyl ether as a polymerization inhibitor, and 1.32 g of potassium hydroxide powdered to 20 to 30 ml (purity).
85%・0.02 mol), and after raising the temperature to 75-80℃,
The reaction system was kept under reduced pressure at 250 to 300 mmHg, and the reaction was allowed to proceed for 30 minutes while blowing a small amount of air into the reaction solution. Methanol produced as a by-product during the reaction was distilled out of the system by azeotropy with methyl methacrylate. Next, 74 g (1 mole) of glycide was added to the reaction system, and the transesterification reaction was carried out at 80° C. for 2 hours. Methanol produced as a by-product during this reaction was continuously distilled out of the reaction system by azeotropy with methyl methacrylate. As a result of gas chromatography of this reaction mixture,
It was confirmed that the conversion rate of glycide was 99.0% and the production rate of glycidyl methacrylate was 97.5%.
After cooling the resulting reaction mixture, it was filtered to recover the catalyst, the filtrate was passed through a continuous distillation machine to recover excess methyl methacrylate, and continuous distillation was carried out again.
127 g of glycidyl methacrylate was obtained. (purity
98.5%, yield 89.3%) Example 3 In the same manner as in Example 1, methyl methacrylate
600g (6 moles), hydroquinone as polymerization inhibitor
0.2 g, 50-60 mesh powdered sodium hydroxide
0.6 g (0.02 mol) was charged, the temperature was raised to 80°C, and the reaction was carried out for 40 minutes in the same manner as in Example 1. Next, glycide
74 g (1 mol) was added, and the reaction was carried out at 80° C. for 2 hours and 30 minutes in the same manner as in Example 1. The production rate of glycidyl methacrylate was 97%. 126.6g by distillation
of glycidyl methacrylate was obtained. (Purity 98.0
%, yield 89%).

Claims (1)

[Claims] 1. In the transesterification reaction between methyl methacrylate and glycide, an alkali metal hydroxide and methyl methacrylate are reacted in advance to synthesize an alkali metal methacrylate salt in the reaction system,
A method for producing glycidyl methacrylate, which comprises then adding glycide and carrying out a transesterification reaction. 2. The manufacturing method according to claim 1, wherein the alkali metal hydroxide is potassium hydroxide or sodium hydroxide. 3. The production method according to claim 1 or 2, wherein the amount of alkali metal hydroxide used is 0.01 to 0.05 mol% based on glycide.