JPS647069B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides 4'-cyanophenyl 4-(4), which is expected to find useful use as a material in the electronics industry.
-Process for producing substituted benzyloxy)benzoates. There have been few reports regarding the method for producing the above compound, and the present inventor has developed a method for producing the compound using 4-cyanophenol, 4-hydroxybenzoic acid, and 4-alkyl (or alkoxy) benzoic acid as starting materials. As a result of research on the method, (1) 4-cyanophenol and 4-acetoxybenzoyl chloride were reacted to obtain 4'-cyanophenyl 4-acetoxybenzoate, (2) 4'-cyanophenyl 4-acetoxybenzoate was then reacted with Alcoholysis to obtain 4'-cyanophenyl 4-hydroxybenzoate, (3) further 4'-cyanophenyl 4-hydroxybenzoate and 4-alkyl (or aryl) benzoyl chloride or 4-alkoxy (or aryloxy) benzoyl chloride. General formula for reaction

[Formula] [Here, R is an alkyl group, alkoxy group, aryl group, or aryloxy group having 1 to 10 carbon atoms] 4'-cyanophenyl 4-(4-substituted benzyloxy)benzoate can be produced with good yield. This discovery led to the completion of the present invention. The present invention is characterized by specifying the starting materials as described above and by combining the reaction steps. That is, first, 4-alkyl (or alkoxy or aryl or aryloxy)benzoic acid and 4-
Although the desired product can be obtained by reacting hydroxybenzoic acid and then reacting with 4-cyanophenol, it is difficult to separate and purify the unreacted raw material and the product, making it difficult to obtain a practical yield. A combination of raw materials and processes is required. Each step will be specifically explained below. (1) 4-cyanophenol and 4-acetoxybenzoyl chloride are reacted to produce 4'-cyanophenyl 4-acetoxybenzoate. 4-acetoxybenzoyl chloride is 4-hydroxybenzoic acid

The hydroxyl group of [Formula] is acetylated and converted into a carboxylic acid chloride, and such treatment has an important meaning in this step. 4
If the hydroxyl group is not protected in advance by -acetoxy substitution, resin formation will occur during acid chloridation, resulting in a decrease in the yield of the target product. Moreover, in the case of 4-acetoxy substitution, 4'-cyanophenyl 4-acetoxybenzoate is It also exhibits a unique behavior in that it can selectively change only the acetoxy group to a hydroxyl group without decomposing the benzoate ester bond. Furthermore, it is necessary to react in the form of a carboxylic acid chloride, and in the case of a free acid, the reactivity is low. In the reaction of 4-cyanophenol and 4-acetoxybenzoyl chloride, pyridine, ether, benzene, toluene, etc. are used as a solvent. Room temperature is sufficient for the reaction temperature, and heating may, of course, be used if necessary. The reaction time is approximately several hours. The molar ratio of 4-cyanophenol/4-acetoxybenzoyl chloride is selected from the range of 0.7 to 1.3/1. After the reaction is completed, the resulting 4'-cyanophenyl 4
- Acetoxybenzoate is extracted with a suitable solvent such as ethyl acetate or ether, and this is further washed with an aqueous alkaline solution to extract and remove unreacted raw materials into the aqueous layer. The solvent is distilled off from the organic layer to obtain crystals of 4'-cyanophenyl 4-acetoxybenzoate. (2) Produce 4'-cyanophenyl 4-hydroxyacetoxybenzoate by alcoholyzing 4'-cyanophenyl 4-acetoxybenzoate. This step is an operation in which the acetoxy group at the 4-position is alcohololyzed to replace it with a hydroxyl group in order to carry out step (3). As described above, the hydroxyl group protected with an acetoxy group can be easily converted to a hydroxyl group without decomposing the ester bond of benzoate. Alcoholysis is carried out by dissolving the raw material in an alcohol such as methanol or ethanol and using an acid catalyst. Suitable acids include hydrochloric acid, sulfuric acid, P-toluenesulfonic acid, and strong acid type ion exchange resins such as naphion. The acid is preferably 0.01 to 0.5 mol based on the raw material.
It is used in a proportion of 0.05 to 0.1 mole. The decomposition temperature is advantageously reflux. After completion of the alcoholysis, the alcohol is distilled off to obtain crystals of 4'-cyanophenyl 4-hydroxybenzoate. If necessary, in order to remove the acid, it is dissolved in a suitable solvent, washed with water, and further purified by recrystallization. (3) 4'-cyanophenyl 4-hydroxybenzoate is reacted with 4-alkyl (or alkoxy or aryl or aryloxy) benzoyl chloride to produce 4'-cyanophenyl 4-(4-substituted benzoyloxy) benzoate. 4-Alkyl (or alkoxy or aryl or aryloxy)benzoyl chloride is 4
-alkyl (or alkoxy or aryl or aryloxy)benzoic acid

[Formula] is converted into the acid chloride form, and by this operation, 4′-
The reaction with cyanophenyl 4-hydroxybenzoate proceeds easily. The alkyl group, alkoxy group, aryl group, or aryloxy group preferably has 1 to 10 carbon atoms, and n-butyl, n-hexyloxy, phenyl, and phenyloxy groups are particularly useful. In the reaction of 4'-cyanophenyl 4-hydroxybenzoate and 4-alkyl (or alkoxy or aryl or aryloxy) benzoyl chloride, pyridine, ether, benzene, toluene, etc. are used as a solvent. Room temperature is sufficient for the reaction temperature, but heating may be applied if necessary. The reaction time is approximately several hours. The molar ratio of 4'-cyanophenyl 4-hydroxybenzoate/4-alkyl (or alkoxy or aryl or aryloxy) benzol chloride is selected from the range of 0.7 to 1.3/1. After the reaction is completed, the resulting 4'-cyanophenyl 4
-(4-Substituted benzyloxy)benzoate is extracted with a suitable solvent such as ethyl acetate or ether, and this is further washed with an aqueous alkaline solution to extract and remove unreacted raw materials into the aqueous layer. The solvent is distilled off from the organic layer to obtain crystals of 4'-cyanophenyl 4-(4-substituted benzyloxy)benzoate. Next, the method of the present invention will be explained in more detail by giving examples. Example 1 10 g of 4-cyanophenol was dissolved in 15 mg of pyridine, and 50 ml of ether was added thereto. Add to this 20g of 4-acetoxybenzoyl chloride and 50ml of ether.
The mixture was added dropwise at room temperature, and the reaction was carried out for 2.5 hours. After the reaction was completed, the solvent was distilled off, and the residue was dissolved in 1000 ml of ethyl acetate. After washing the ethyl acetate layer three times with 250 ml of 6% aqueous hydrochloric acid and 250 ml of 5% aqueous sodium hydroxide solution and then with water, ethyl acetate was distilled off to obtain 21.6 g of crystals of 4'-cyanophenyl 4-acetoxybenzoate. It was done. Next, 20 g of the 4'-cyanophenyl 4-acetoxybenzoate, 300 ml of methanol, and 0.5 ml of concentrated hydrochloric acid.
were mixed and subjected to alcoholysis under reflux for 4.5 hours. After the reaction is complete, methanol is distilled off.
Crystals of 4'-cyanophenyl 4-hydroxybenzoate were obtained. The crystals were dissolved in ethyl acetate, washed with water, and the ethyl acetate was distilled off to obtain 16.4 g of purified 4'-cyanophenyl 4-hydroxybenzoate crystals. Dissolve 10.8 g of 4'-cyanophenyl 4-hydroxybenzoate in 75 ml of pyridine, and add 4-n
A mixture of 13.0 g of -hexyloxybenzoyl chloride and 70 ml of ether was added dropwise at room temperature, and the reaction was carried out for 5 hours. After the reaction was completed, the solvent was distilled off, the residue was dissolved in 1300 ml of ethyl acetate, and this was dissolved in 6% aqueous hydrochloric acid solution.
After washing three times with 500 ml and 300 ml of 5% aqueous sodium hydroxide solution, and then with water, ethyl acetate was distilled off to obtain 19.0 g of 4'-cyanophenyl 4-(4-n-hexyloxybenzoyloxy)benzoate. Ta. The melting point of the crystals was 133°C. Example 2 An experiment similar to Example 1 was conducted using 10 g of 4-n-butylbenzoyl chloride instead of 4-n-hexyloxybenzoyl chloride. 17.0 g of 4'-cyanophenyl 4-(4-n-butylbenzoyloxy)benzoate was obtained. The melting point of the crystals was 126°C.

Claims (1)

[Claims] 1 (1) A step of reacting 4-cyanophenol and 4-acetoxybenzoyl chloride to obtain 4'-cyanophenyl 4-acetoxybenzoate, (2) Alcoholizing 4'-cyanophenyl 4-acetoxybenzoate. (3) Reacting 4'-cyanophenyl 4-hydroxybenzoate with 4-alkyl (or aryl) benzoyl chloride or 4-alkoxy (or aryloxy) benzoyl chloride; [Formula] [Here, R is an alkyl group or alkoxy group having 1 to 10 carbon atoms, an aryl group, or an aryloxy group]
A process for producing a benzoate, which comprises sequentially combining the following steps to obtain 4'-cyanophenyl 4-(4-substituted benzyloxy)benzoate.