JPS6022693B2 - Production method of methacrylic acid ester - Google Patents

Description

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

Methacrylic acid ester is an important compound as an industrial raw material.

Currently, this methacrylic acid ester is produced from acetone cyanohydrin, water and alcohol in the presence of an equimolar amount of sulfuric acid. In addition to the desire to switch to inexpensive raw materials that can be supplied in large amounts, the above production method has the major problem of producing a large amount of ammonium sulfate as a by-product, making it difficult to dispose of it. The present inventors have discovered that methacrylic acid amide is produced by a hydration reaction of methacrylonitrile bound by ammoxidation of isobutylene, that the production method has been technically established, and that it can be combined at low cost and in large quantities; Since ammonium sulfate is not produced when methacrylic acid ester is produced from methacrylic acid amide and alcohol, extensive research was conducted into this production method.

On the other hand, methods for producing carboxylic acid esters by reacting certain types of carboxamides with alcohols have been known, for example, a method for obtaining Q-hydroxyisobutyric acid esters by alcoholysis of Q-hydroxyisobutyramide has been approved by special authorities. It is disclosed in Publication No. 52-3015.

However, the alcoholysis catalysts described in these known documents have low activity and low yield in the alcoholysis of methacrylic acid amide, and when the conversion rate is increased, the selectivity decreases dramatically. At present, the problem has not been fully resolved. The reason for this is that the starting material, methacrylic acid amide, and the product, methacrylic acid ester, are easily polymerized, and addition of alcohol to unsaturated double bonds, addition of produced ammonia, and other side reactions occur. Therefore, it has been difficult to obtain methacrylic acid ester in high yield and high selectivity.
The present inventors have discovered that from methacrylic acid amide and alcohol,
As a result of studying a reaction method that does not produce polymers and exhibits high yield and high selectivity, we found that by using a special catalyst as described below, we could avoid the above polymerization reaction and side reactions, and increase the production of methacrylic acid ester. It has been discovered that it can be produced extremely advantageously with high yield and high selectivity, leading to the present invention. That is, in producing methacrylic acid ester from methacrylic acid amide and alcohol, the present invention uses lead, tin bromide, fluoride, chloride, nitrate, phosphate and borate; titanium bromide; The present invention relates to a method for producing methacrylic acid ester, characterized in that the reaction is carried out using at least one member selected from the group consisting of cadmium nitrate, fluoride, bromide, and cadmium chloride.

The reaction of the present invention is carried out between methacrylic acid amide and alcohol in the presence of the above catalyst, with or without a reaction medium.

Alcohols used in the present invention include methanol,
Primary alcohols such as ethanol, propanol, n-butanol, etc.

These alcohols are used in a molar amount approximately 2 to 50 times that of methacrylic acid amide. The catalyst used in the present invention is as described above, but it is used in an amount of 0.01 to 100 mol% based on the methacrylic acid amide, and when it is less than 0.01 mol%, the yield of methacrylic acid ester is decreases, which is not desirable.

The reaction temperature is preferably 50 pm to 300 qoC, and more preferably 100 pm to 250 qoC.

The reaction pressure is appropriately determined depending on the type and amount of alcohol used, the amount of water, and the reaction temperature, but is 5 to 1
00k9/ground, more preferably 10 to 50k9/ground.

It is preferable to carry out the reaction in the present invention while removing the generated ammonia from the reaction system intermittently or continuously from the viewpoint of coloration of the methacrylic acid 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, or removing it from the reaction system together with the reaction medium. A method such as removing the crab is also possible. Further, although it is preferable from the viewpoint of yield that water not be present in the reaction system of the present invention, the reaction can be carried out even if water is present in an amount of one sonic molar amount per methacrylic acid amide.

Examples are shown below.

Example 1 85 ml of methacrylamide, 200 ml of methanol, and 5 ml of lead nitrate were charged into a 500 cc autoclave, and the pressure was increased to 20 ml.
The mixture was kept at 9' and reacted for 5 hours at 170 qo under Takaazusa.

During this time, nitrogen gas was blown into the reactor at a rate of 1 per minute.
The ammonia produced was released from the manipulator along with nitrogen gas. After the reaction, the reaction solution was cooled and the reaction product was analyzed by gas chromatography.

The results are shown below. Example 2 85 tons of methacrylamide, 200 tons of ethanol, and 7 tons of cadmium bromide were charged into a 500 cc autoclave, and while maintaining the pressure at 30 k9/carp, the mixture was heated at Fumoto Azusa, 190°C, 4
Allowed time to react.

During this time, nitrogen gas was introduced into the reactor at a rate of 2 per minute, and the ammonia produced was released from the pressure holder together with the nitrogen gas. After the reaction, the reaction solution was cooled and analyzed by gas chromatography.

The results were as follows. Example 3 Methacrylamide 85 times, methanol 300 times, water 20 times
The mixture was reacted with 50% of lead nitrate under the same reaction conditions as in Example 1.

The results were as follows. Example 4 85 parts of methacrylamide, 200 parts of methanol, 2 parts of cadmium iodide, and 12 parts of Pb were reacted under the same reaction conditions as in Example 1.

The results were as follows. Example 5 85 parts of methacrylamide and 300 parts of methanol were reacted under the same reaction conditions as in Example 1 using various catalysts shown in Table 1. The results are shown in Table 1.

Table 1 Comparative Example A reaction was carried out under the same reaction conditions as in Example 1 using methacrylamide 859, methanol 200, and catalyst 5 shown in Table 2.

The results are shown in Table 2.

2

Claims (1)

[Claims] 1. In producing methacrylic acid ester from methacrylic acid amide and alcohol, lead, tin bromide, fluoride, iodide, nitrate, phosphate, and borate; titanium bromide; 1. A method for producing methacrylic acid ester, which comprises carrying out a reaction using at least one member selected from the group consisting of cadmium nitrate, fluoride, bromide, and iodide. 2. The method for producing a methacrylic acid ester according to claim 1, wherein the reaction is carried out while the ammonia produced by the reaction is removed from the reaction system intermittently or continuously. 3. The method for producing a methacrylic ester according to claim 1 or 2, wherein the reaction is carried out in the presence of water in an amount not more than 10 times the molar amount of methacrylic acid amide.