JPS5938937B2 - Method for producing methacrylic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing methacrylic acid ester from methacrylamide and alcohol.

Methacrylic acid ester is an important compound as an industrial raw material, and currently, this methacrylic acid ester is produced from acetone cyanohydrin and alcohol in the presence of equivalent moles of sulfuric acid. However, the supply of acetone cyanohydrin as a raw material is becoming limited, and it is therefore desirable to switch to a cheap raw material that can be supplied in large quantities.In addition, the above structural method uses concentrated sulfuric acid, so the reaction equipment is The material is expensive, and a large amount of ammonium sulfate is produced as a by-product, making it difficult to dispose of it, which is a major problem.

Therefore, the present inventors discovered that methacrylamide is produced by the hydration reaction of methacrylonitrile obtained by ammoxidation of isobutylene, and can be supplied in large quantities at low cost. We have conducted extensive research on manufacturing methods that do not use concentrated sulfuric acid. Hitherto, methods for producing carboxylic acid esters from certain carboxylic acid amides and alcohols have been known.

However, the esterification catalysts described in these known documents have low activity and low yield in alcohol rinsing of methacrylamide, and when the conversion rate is increased, the selectivity decreases significantly. At present, this problem has not been fully resolved. The reason for this is thought to be that the starting material, methacrylamide, and the product, methacrylic ester, are easily polymerized, and addition of alcohol to unsaturated double bonds, addition of produced ammonia, and other side reactions occur. As a result, it was difficult to obtain methacrylic acid ester in high yield and high selectivity.

The present inventors investigated a catalyst that does not produce a polymer from methacrylamide and alcohol, and provides high yield and high selectivity, and found that by using the catalyst described below,
The present invention has been achieved by discovering that methacrylic acid esters can be produced extremely advantageously in high yield and high selectivity without inducing the above-mentioned polymerization reactions and side reactions.

That is, in the present invention, when producing methacrylic acid ester from methacrylamide and alcohol, the catalyst is selected from the group consisting of zinc bromide, iodide, nitrate, sulfate, borate, phosphate, and carboxylate. The present invention relates to a method for producing a methacrylic acid ester, characterized in that at least one type of methacrylic acid ester is used.

In the reaction of the present invention, methacrylamide and alcohol are
It is carried out in the presence of the abovementioned catalysts, with or without a reaction medium.

As the carboxylic acid salt, salts of formic acid, acetic acid, propionic acid, benzoic acid, etc. other than methacrylic acid are used. The alcohol used in this reaction is a primary alcohol such as methanol, ethanol, propanol, n-butanol, etc., and these alcohols are used in an amount of approximately 2 to 50 times the molar amount of methacrylamide.

The amount of catalyst used is 0.0 relative to methacrylamide.
1 mol% or more is preferably used, more preferably 0
．． It is 1 to 100 mol%.

The reaction temperature is often 500 to 300°C, more preferably 100 to 250°C.

Although it is preferable from the viewpoint of yield that no water be present in the reaction system of the present invention, the reaction will proceed even if a small amount of water is present, for example, in an amount of 10 times the mole % or less relative to methacrylamide. The reaction pressure depends on the type and amount of alcohol used,
It can be determined appropriately depending on the amount of water and the reaction temperature, but 5 to 10
0kg/Crli, more preferably 10-501<g
/Cd.

During the reaction, it is preferable to remove the generated ammonia from the reaction system intermittently or continuously from the viewpoint of coloration of the methacrylic ester, yield, and selectivity.

Removal methods include introducing a gas that does not participate in the reaction, such as nitrogen, air, argon, etc., into the reaction system as a carrier gas to effectively remove the generated ammonia;
Alternatively, a method of distilling it out of the reaction system together with the reaction medium is also possible. The details of the present invention will be explained below with reference to Examples. Example 1 Methacrylamide 857, methanol 3
007, 3y of zinc nitrate was charged into a 500CC autoclave, the pressure was maintained at 20kg/Cd, and the temperature was heated at 170℃ under stirring.
The reaction was carried out for 3 hours.

During this time, nitrogen gas was blown into the reactor at a rate of 21/min, and the ammonia produced was discharged from the pressure holding device together with the nitrogen gas. After the reaction, the reaction solution was cooled and the reaction product was analyzed by gas chromatography. The results were as follows. Example 2 Methacrylamide 857, ethanol 300V, and zinc iodide 57 were charged into a 500CC autoclave and the pressure was set to 2.
The reaction was carried out at 180° C. for 4 hours with stirring while maintaining the pressure at 5 kg/Cd.

During this time, nitrogen gas was introduced into the reactor at a rate of 21/min, and the ammonia produced was discharged from the pressure holder together with the nitrogen gas. The results were as follows. Example 3 Methacrylamide 857, methanol 3007, water 80
y, prepare 5y of zinc nitrate in a 500CC autoclave,
The reaction was carried out at 170° C. for 4 hours while maintaining the pressure at 20 kg/Cd.

During this time, nitrogen gas was introduced into the reactor at a rate of 31/min, and the ammonia produced was discharged from the pressure holder together with the nitrogen gas. The results were as follows. Example 4 Methacrylamide 85y, methanol 250y1, zinc sulfate 2y, and zinc acetate 27 were reacted under the same reaction conditions as in Example 1.

The results were as follows.

Example 5 A reaction was carried out using 85 y of methacrylamide and 300 y of methanol under the same reaction conditions as in Example 1 using various catalysts 57 shown in Table 1.

The results were as follows.

Comparative Example Methacrylamide 857 and methanol 3007 were reacted under the same reaction conditions as in Example 1 using various catalysts 5f shown in Table 1.

Claims (1)

[Claims] 1. In producing methacrylic acid ester from methacrylamide and alcohol, zinc bromide,
A method for producing a methacrylic ester, which comprises carrying out a reaction using at least one selected from the group consisting of iodides, nitrates, sulfates, borates, phosphates, and carboxylates. 2. The method according to claim 1 for producing methacrylic acid ester from methacrylamide, alcohol and water. 3. The method for producing a methacrylic ester according to claims 1 and 2, wherein the reaction is carried out while the ammonia produced by the reaction is removed from the reaction system intermittently or continuously.