JPH0116822B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing phenyl acetic acid ester by reacting phenylacetic acid and ketene to produce phenyl acetic anhydride, and then reacting with alcohol. Phenyl acetate esters are useful as intermediate raw materials for various fine chemicals. As a conventional method, a method is known in which phenylacetic acid and alcohol are dehydrated by refluxing in the presence of an acid catalyst, azeotropic dehydration with benzene, or the like to obtain the corresponding phenylacetic acid ester. However, this method has a major drawback in that it requires a long time, and is not an industrially advantageous method. In addition, phenylacetic acid anhydride (Ar-
It is also known to react CH ₂ CO) ₂ O with an alcohol to obtain the corresponding phenyl acetate. (Ar−CH ₂ CO) ₂ O＋ROH
→Ar−CH ₂ COOR+Ar−CH ₂ COOH However, this method has the disadvantage that it is difficult to prepare the acid anhydride itself, and the reaction with alcohol produces equimolar amounts of the ester and the original phenylacetic acid. That is, the drawback was that the upper limit of the yield was 50% based on the number of moles of acid anhydride. According to the method of the present invention, the corresponding phenyl acetate can be almost quantitatively produced by a very simple procedure of reacting ketene with phenylacetic acid and then reacting the generated acid anhydride with alcohol at room temperature for a short period of time. Can be manufactured. That is, in the following reaction equation
The present invention was achieved by discovering that only route (A) progresses and route (B) does not progress at all. Ar represents a substituted or unsubstituted phenyl group. The present invention is based on the general formula () (X and Y in the formula represent a hydrogen atom, a lower alkyl group, a hydroxyl group, a lower alkoxy group, and a halogen atom, respectively) are reacted with ketene to form the general formula () (X and Y in the formula have the same meanings as above)
A general formula () characterized in that it produces phenyl acetic anhydride represented by and then reacts with alcohol. The present invention relates to a method for producing phenyl acetate represented by the formula (R in the formula represents an alkyl group having 1 to 10 carbon atoms). Specifically, the phenylacetic acid represented by the general formula () used in the method of the present invention includes unsubstituted phenylacetic acid, 4-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid,
-methoxyphenylacetic acid, 3-ethylphenylacetic acid, 3,4-dimethoxyphenylacetic acid, 3,5-
Diethoxyphenylacetic acid, 2-chlorophenylacetic acid, 3,4-dichlorophenylacetic acid, 4-hydroxy-3-methoxyphenylacetic acid, 2-hydroxy-5-chlorophenylacetic acid, 4-hydroxy-
Examples include 3-chlorophenylacetic acid. The reaction is carried out by introducing ketene into an organic solvent of phenylacetic acid. The amount of ketene used is 0.5 to 5 mol, especially 1 mol per 1 mol of phenylacetic acid.
~3 mol is preferred. The organic solvent used is not particularly limited as long as it is safe for ketene, such as dioxane, tetrahydrofuran, benzene, toluene,
Examples include xylene and 1,2-dimethoxyethane. The amount of organic solvent used is 1 phenyl acetic acid.
5 to 50 ml, particularly 10 to 30 ml per g. The reaction temperature is not particularly limited and is suitably 0 to 100°C. Phenyl acetic anhydride represented by the general formula () can be obtained by the above reaction. Then, the phenylacetic anhydride thus obtained is separated from the reaction system, or without being separated, an alcohol is added thereto and the reaction is carried out to produce a phenylacetic acid ester. The alcohol used in the method of this invention is suitably an aliphatic alcohol having 1 to 10 carbon atoms. The amount of alcohol used is preferably 1 to 100 mol, particularly 10 to 50 mol, per 1 mol of phenylacetic acid. The reaction temperature is 5 to 35°C, and the reaction proceeds sufficiently at a temperature around room temperature. The product produced by the method of the present invention is phenyl acetate represented by the general formula (), specifically methyl phenyl acetate, 4-
Ethyl hydroxyphenyl acetate, ethyl 4-methoxyphenyl acetate, propyl 3-ethyl phenylacetate, butyl 3,4-dimethoxyphenyl acetate,
3,5-diethoxyphenyl octyl acetate, 2-
Hexyl chlorophenyl acetate, ethyl 3,4-dichlorophenyl acetate, butyl 4-hydroxy-3-methoxyphenylacetate, 2-hydroxy-5-
Decyl chlorophenyl acetate, 4-hydroxy-3
-chlorophenylhexyl acetate and the like. By carrying out the method of the present invention, phenylacetic acid ester can be produced from phenylacetic acid in high yield. Examples 1 to 7 0.1 mol of various phenylacetic acids and 100 ml of dioxane
The mixture was charged into a 200 ml reactor equipped with a glass filter blowing tube, 0.3 mol of ketene was blown into the system, the atmosphere in the system was replaced with nitrogen, 50 ml of various alcohols were added, and the mixture was stirred at 20° C. for about 5 minutes. GLC the reaction solution
Analysis confirmed that no raw material phenylacetic acid remained in any case. In addition, the generated phenyl acetate was similarly quantified by GLC analysis, and the yield was calculated using the following formula. Yield of phenylacetic acid ester (%) = produced phenylacetic acid ester (mol)/charged phenylacetic acid (mol) x 100 The results are shown in Table 1.

【table】

[Table] Examples 8 to 11 Various phenyl acetic acids having a hydroxyl group on the benzene ring
The same procedure as in Example 1 was carried out except that 0.1 mol was used. The results are shown in Table 2.

【table】

[Table] In these cases, when 300 ml of 2N-H ₂ SO ₄ is added to the obtained phenyl acetate and hydrolyzed at approximately 100°C for 5 hours, the acetoxyl group is hydrolyzed to the phenolic hydroxyl group, resulting in the corresponding reaction. Hydroxyphenyl acetate was obtained in high yield (yield over 95% in all cases).

Claims (1)

[Claims] 1 General formula () (X and Y in the formula represent a hydrogen atom, a lower alkyl group, a hydroxyl group, a lower alkoxy group, and a halogen atom, respectively) are reacted with ketene to form the general formula () (X and Y in the formula have the same meanings as above)
A general formula () characterized in that it produces phenyl acetic anhydride represented by and then reacts with alcohol. (R in the formula represents an alkyl group having 1 to 10 carbon atoms) A method for producing phenyl acetate ester.