JPS5938934B2 - Method for producing carboxylic acid alkenyl ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the method for producing carboxylic acid alkenyl esters by transesterification.

Conventionally, as a method for producing carboxylic acid alkenyl esters (especially carboxylic acid vinyl esters) by transesterification, an aliphatic or aromatic carboxylic acid and a vinyl ester are transesterified, and the raw material vinyl ester is Methods of producing different carboxylic acid vinyl esters are known, but in carrying out this reaction, mercury salts such as mercury sulfate and mercury acetate are used as catalysts, or palladium chloride and alkali metals are used as co-catalysts. A method of using a chloride such as sodium chloride in combination is known.

However, the former method requires the use of toxic mercury compounds, and the latter method decomposes the catalyst and produces hydrogen chloride, which not only causes side reactions but also corrodes the reactor. There is a problem with that.

Regarding this hydrogen chloride production, if a base is added to the reaction system for the purpose of neutralizing it, the reaction activity of the catalyst will be greatly reduced. On the other hand, a method is known in which a combination of palladium acetate and a chelate forming agent such as pipyridyl or 1,10-phenanthroline is used as a catalyst [Tetrahedron Vol. 28, p. 233 (1972)]; It is necessary to separately synthesize a chelate compound using the above-mentioned chelate-forming agent, and since such a chelate-forming agent is expensive, there is a disadvantage that the cost of the product is high.

The present inventors have conducted extensive research to solve the disadvantages of the conventional methods described above, and have arrived at the present invention, which is based on the general formula (where R1 is a hydrogen atom or an aliphatic or aromatic carboxylic acid represented by the general formula (in which R2 represents a hydrogen atom or a monovalent hydrocarbon group, R3 represents an alkenyl group, In the presence of palladium acetate and an alkali metal carboxylate, the general formula (R1 and R3 The present invention relates to a method for producing a carboxylic acid alkenyl ester represented by (same as above).

To explain this, the aliphatic or aromatic carboxylic acid used as one of the raw materials in the method of the present invention is
), and the aliphatic carboxylic acids include saturated carboxylic acids having 1 to 20 carbon atoms and derivatives thereof, such as formic acid, propionic acid, lactic acid, lauric acid, monochloroacetic acid, and unsaturated carboxylic acids. Carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, etc.
Examples of aromatic carboxylic acids include benzoic acid and cinnamic acid.

The ester used as the other raw material is represented by the above formula 51), and examples thereof include vinyl formate, vinyl acetate, vinyl lactate, vinyl cyclopropanecarboxylate, isopropenyl acetate, allyl acetate, etc. Ru.

Next, the catalyst used in the method of the present invention is a combination of palladium acetate and an alkali metal carboxylate as a co-catalyst. Examples include salts with carboxylic acids.

In carrying out the transesterification reaction, the mixing molar ratio of the carboxylic acid represented by formula (1) and the ester represented by formula (11) is 20: depending on the equilibrium relationship of the transesterification reaction.
The ratio is preferably 80 to 80:20, particularly 40:60 to 60:40, and the amount of catalyst used is 0.005 to 0.5 weight of palladium acetate per 100 parts by weight of the mixture of the carboxylic acid and ester. 1 to 15 parts by weight of the alkali metal carboxylate. Since the solubility of this alkali metal carboxylate salt in the reaction system is not so great, the amount of this salt used is generally up to about 15 parts by weight as described above. The transesterification reaction is carried out by charging the raw materials and catalyst in the above-mentioned ratios into a reactor and stirring. However, if the reaction temperature is too high, the catalyst will decompose, so it is generally set at 80°C. It is desirable not to exceed this limit. When reacted in this manner, the transesterification reaction proceeds according to the equilibrium composition of the reaction system, and carboxylic acid alkenyl esters corresponding to the formula (8) are produced depending on the type of raw material. In addition, in carrying out this reaction,
If necessary, a solvent may be used, and tetrahydrofuran, for example, is preferred as this solvent.

However, aromatic solvents may inhibit the progress of the reaction. After the reaction is completed, the catalyst palladium acetate can be almost completely recovered as reduced palladium, and the alkali metal carboxylate used as a cocatalyst and the carboxylic acid by-produced by transesterification can also be recovered using normal methods. It can be easily collected.

A remarkable feature of the process of the invention is that, by means of the combination of catalysts described above, the desired carboxylic acid alkenyl esters can be obtained in high yields without undesirable side reactions. The following will be described in detail with reference to Examples and Comparative Examples.

Example 1 7.2f7 of acrylic acid, 8.6f7 of vinyl acetate, 0.227g of palladium acetate, and 1.967g of potassium acetate were charged into a reactor equipped with a stirrer, a thermometer, and a cooling tube, and the internal temperature was adjusted while stirring. When the reaction was maintained at 65° C. for 2 hours, 4y of the target vinyl acrylate was produced, and 2.47 by-product acetic acid was recovered.

Comparative Example When the reaction was carried out in the same manner as in Example 1 except that no potassium acetate was used, only 0.97 of vinyl acrylate was produced.

Example 2 In a reactor similar to Example 1, acrylic acid 72
7. When 867% vinyl acetate, 0.117% palladium acetate, and 19.67% potassium acetate were charged and reacted at 25°C for 24 hours with stirring, 24.3y of vinyl acrylate was produced, and by-product acetic acid was produced. It was recovered in 14.9y.

Example 3 In a reactor similar to Example 1, 7.27 g of acrylic acid, 7.2 f of vinyl formate, 0.227 g of palladium acetate, and 0.987 g of potassium acetate were charged, and the internal temperature was maintained at 40°C while stirring. When the reaction was carried out for 3 hours, 1,97 units of vinyl acrylate were produced.

Example 4 In a reactor similar to Example 1, acrylic acid 7.
27. Prepare a predetermined amount of the raw material ester shown below, palladium acetate 0.227 and potassium acetate 0.987,
When the reaction was carried out for 2 hours while stirring while maintaining the internal temperature at 65° C., the amount of vinyl acrylate produced was as follows depending on the type of raw material ester.

Example 5 In Example 4, 1 of allyl acetate was used as the raw material ester.
When the transesterification reaction was carried out in the same manner for 5 hours except that 0y was used (however, the reaction temperature was 40°C), 1.0y of allyl acrylate was produced.

Example 6 A transesterification reaction was carried out in the same manner as in Example 4 except that 10 g of isopropenyl acetate was used as the raw material ester for 5 hours (reaction temperature: 40° C.), and 0.57 isopropenyl acrylate was produced.

Example 7 In a reactor similar to Example 1, predetermined amounts of each of the raw material carboxylic acid and ester shown below and 0.00% palladium acetate were added.
227 and 0.98 y of potassium acetate were charged, and in each case, the internal temperature was maintained at 65° C. and the transesterification reaction was carried out for 2 hours. The amounts of each carboxylic acid alkenyl ester produced were as follows.

' Example 8 Into the same reactor as in Example 1, 747 propionic acid, 867 vinyl acetate, 0.11f7 palladium acetate, and 9.8y potassium acetate were charged, and the internal temperature was brought down to 4 y while stirring.
When the mixture was kept at 0°C and transesterified for 5 hours, 49.57 units of vinyl propionate were produced.

Example 9 In a reactor similar to Example 1, 9.57% of monochloroacetic acid,
8.67% of vinyl acetate, 0.227% of palladium acetate, and 0.987% of potassium acetate were charged, and the internal temperature was maintained at 40° C. and transesterification was carried out for 17 hours, resulting in 5.57% of monochlorovinyl acetate.

Example 10 In a reactor similar to Example 1, 5.47 cinnamic acid, 1727 vinyl acetate, 0.447 ml of palladium acetate, 0.39 y1 of potassium acetate, and 2 ml of tetrahydrofuran as a solvent were added.
When 8.87 was added and reacted for 16 hours while stirring and keeping the internal temperature at 40°C, vinyl cinnamate was converted to 2.87.
07 was generated.

Claims (1)

[Claims] 1. An aliphatic or aromatic carboxylic acid represented by the general formula R^1COOH (R^1 in the formula represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group); General formula R^2COOR^3 (R^2 in the formula is a hydrogen atom or a monovalent hydrocarbon group, R^
3 represents an alkenyl group, except when R^2 is the same as R^1 above) is subjected to a transesterification reaction in the presence of palladium acetate and an alkali metal carboxylate. A method for producing a carboxylic acid alkenyl ester represented by the general formula R^1COOR^3 (R^1 and R^3 are the same as above), characterized by: