JP3617556B2 - Production of methyl cyanoisobutyrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing methyl cyanoisobutyrate synthesized by an addition reaction of hydrogen cyanide to methyl methacrylate. Methyl cyanoisobutyrate is rich in reactivity, is an industrially useful intermediate material for carboxylic acids, etc., and is also used in large quantities as a solvent for polymers, and is an industrially extremely important chemical product.
[0002]
[Prior art]
Addition of hydrogen cyanide to a carbon double bond can be carried out by using a substituted olefin compound having a cyano group, a keto group, a nitro group, a carbalkoxy group or other carboxyl derivative group conjugated to the double bond as an alkali metal, It is known to carry out at high temperature and high pressure using cyanides of earth metals, amines, etc. (German published application 1,068,688, G.P808,835, USP2,810,742) ). However, these require industrially expensive high pressure equipment.
Addition of hydrogen cyanide to a methyl methacrylate double bond at normal pressure is performed by using pyrrolidone-2 or alkyl-substituted pyrrolidones (USP 3,644,468) as a solvent in the presence of an alkali metal cyanide. However, when the weight ratio of the solvent to hydrogen cyanide is decreased, the yield decreases accordingly.
Furthermore, a method of using dimethyl sulfoxide (USP 3,644,467) as a solvent in the presence of an alkali metal cyanide is also known. However, in this case, since it is necessary to make excess hydrogen cyanide exist in the reaction system, a step for recovering unreacted hydrogen cyanide after the reaction is required, and the solvent itself is expensive.
As described above, the addition reaction of hydrogen cyanide to the carbon double bond of MMA is carried out at high temperature and high pressure, and when it is carried out at normal pressure, the yield decreases with the decrease in the amount of solvent used and the hydrogen cyanide after the reaction There are drawbacks such as requiring a recovery step.
[0003]
[Problems to be solved by the invention]
When adding hydrogen cyanide to methyl methacrylate at normal pressure, the recovery process of unreacted hydrogen cyanide is not required, an inexpensive solvent is used, and even if the amount of solvent used is reduced, the yield does not decrease. Another object of the present invention is to provide a method for producing methyl cyanoisobutyrate in a high yield.
[0004]
[Means for Solving the Problems]
The inventors have found that methyl cyanoisobutyrate can be obtained in high yield when hydrogen cyanide is added to methyl methacrylate in an amide solvent at normal pressure using an alkali metal salt of an organic acid as a catalyst.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In this invention, it is characterized by using the alkali metal salt of the organic acid which consists of sodium, potassium, lithium which is alkali metal, and a C1-C4 organic acid as a catalyst, and potassium acetate is especially preferable. The usage-amount of organic acid metal salt is 0.4-10 mol% with respect to hydrogen cyanide, Preferably, it is 1.4-8.4 mol%.
[0006]
As the reaction solvent of the present invention, an amide solvent, preferably an N, N-dialkyl aliphatic amide, more preferably dimethylacetamide, dimethylformamide or a mixture thereof is used. When dimethylacetamide or dimethylformamide is used as a reaction solvent and potassium hydroxide, potassium cyanide, triethylamine or the like is used as a catalyst, the yield of the adduct is reduced by reducing the weight ratio of dimethylacetamide or dimethylformamide as a solvent to hydrogen cyanide. Although it tends to decrease, when a potassium salt of an organic acid, particularly potassium acetate, is used as a catalyst, an adduct can be obtained in a high yield even if the weight ratio of the solvent to hydrogen cyanide is lowered. The weight ratio of the amide solvent to hydrogen cyanide is 1.5 or more, and preferably 2.0 or more.
[0007]
Examples of the reaction method for carrying out the present invention include a method in which hydrogen cyanide and methyl methacrylate are fed simultaneously in a solvent, a method in which hydrogen cyanide is fed into a solvent and methyl methacrylate, and the like. Is preferred. The reaction conditions are normal pressure, hydrogen cyanide feed time of 1 to 10 hours, preferably 2 to 5 hours, and aging time of 1 to 6 hours, preferably 0.5 to 3 hours. The reaction temperature is 40 ° C to 170 ° C, preferably 70 ° C to 140 ° C. At a temperature lower than this, the progress of the reaction is slow, and at temperatures higher than this, polymerization of the raw material hydrogen cyanide or methyl methacrylate tends to occur.
[0008]
【The invention's effect】
When hydrogen cyanide is added to methyl methacrylate in an amide solvent at normal pressure using an alkali metal salt of an organic acid as a catalyst, methyl cyanoisobutyrate is obtained in high yield and productivity is improved.
[0009]
【Example】
Example 1
A four-necked flask equipped with a stirrer, reflux condenser, internal thermometer, hydrogen cyanide and methyl methacrylate feed line was charged with 101.6 g of dimethylacetamide and 2.06 g of potassium acetate and heated to 120 ° C. did. 40.0 g (1.48 mol) of hydrogen cyanide and 163.3 g (1.63 mol) of methyl methacrylate were fed over 4 hours, and the solution was heated at 120 ° C. for an additional 2 hours. At 96.4% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 98.6% based on the reacted hydrogen cyanide.
[0010]
Example 2
In the same manner as in Example 1, 101.6 g of dimethylformamide and 2.04 g of potassium acetate were charged and heated to 120 ° C. 39.2 g (1.45 mol) of hydrogen cyanide and 165.9 g (1.66 mol) of methyl methacrylate were fed in about 4 hours, and the solution was heated at 120 ° C. for a further 2 hours. At 95.8% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 98.8% based on the reacted hydrogen cyanide.
[0011]
Example 3
As in Example 1, 101.6 g of dimethylacetamide and 1.93 g of sodium propionate were charged and heated to 120 ° C. 38.8 g (1.43 mol) of hydrogen cyanide and 159.4 g (1.59 mol) of methyl methacrylate were fed over 4 hours and the solution was heated at 120 ° C. for a further 2 hours. At 93.2% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 94.3% based on the reacted hydrogen cyanide.
[0012]
Example 4
In the same manner as in Example 1, 101.6 g of dimethylacetamide and 2.58 g of potassium methacrylate were charged and heated to 120 ° C. 38.2 g (1.41 mol) of hydrogen cyanide and 158.3 g (1.58 mol) of methyl methacrylate were fed in about 4 hours, and the solution was heated at 120 ° C. for another 2 hours. At 91.6% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, corresponding to a yield of 95.4% based on the reacted hydrogen cyanide.
[0013]
Comparative Example 1
Instead of potassium acetate in Example 1, 1.43 g of potassium hydroxide was charged, hydrogen cyanide was fed in 5 hours, and the reaction was carried out in the same manner. With 81.7% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 89.7% with respect to the reacted hydrogen cyanide.
[0014]
Comparative Example 2
Instead of the potassium acetate of Example 2, 1.42 g of potassium hydroxide and 123.5 g of dimethylformamide were charged and heated to 120 ° C. 43.0 g (1.59 mol) of hydrogen cyanide and 189.7 g (1.89 mol) of methyl methacrylate were fed over 4.5 hours, and the solution was heated at 120 ° C. for an additional 2 hours. With 86.5% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 88.0% based on the reacted hydrogen cyanide.
[0015]
Comparative Example 3
In Comparative Example 1, 203.3 g of dimethylacetamide was used, and the reaction was performed in the same manner. With 99.7% hydrogen cyanide conversion, methyl β-cyanoisobutyrate is obtained, which corresponds to a yield of 94.9% based on the reacted hydrogen cyanide.

Claims (1)

Use 0.4～10Mol% relative hydrogen cyanide and sodium are alkali metals, potassium, alkali metal salts of organic acids consisting of lithium and organic acids having 1 to 4 carbon atoms and a catalyst, N, N-dialkyl aliphatic dimethylacetamide amides, using dimethylformamide or mixtures thereof as a solvent, and wherein the Rukoto by adding hydrogen cyanide methyl methacrylate at atmospheric pressure, the production method of Shianoiso methyl butyrate.