Process of preparing 3-trifluoromethyl benzoic acid

Abstract

The process of preparing 3-trifluoromethyl benzoic acid includes the following steps: preparing meta-bis(trichloro methylbenzene) through the reaction of metaxylene and chlorine in meta-bis(trichloro methylbenzene) solvent under the action of initiator or photoinitiator; preparing meta-trichloromethyl trifloromethyl benzene through the fluoridation of meta-bis(trichloro methylbenzene) and hydrogen fluoride in the presence of catalyst, and preparing 3-trifluoromethyl benzoic acid through the hydrolysis reaction of meta-trichloromethyl trifloromethyl benzene in the presence of zinc-containing catalyst and water.

Description

technical field [0001] The present invention relates to the preparation method of 3-trifluoromethylbenzoic acid. Background technique [0002] 3-Trifluoromethylbenzoic acid is a very valuable intermediate, which has been widely used in the fields of pesticides, medicine and fine chemicals. [0003] U.S. Patent (US305203,1962) discloses to be raw material with m-halogenated trifluorotoluene, carries out Grignard reaction, then reacts with carbon dioxide, prepares 3-trifluoromethylbenzoic acid; But, owing to adopted Grignard reaction, thus As a result, the production cost of this route is relatively high, and it is not conducive to mass production. [0004] The Chinese patent (CN1356306) discloses that using m-trifluoromethyl benzyl chloride as a raw material, a chlorination reaction occurs under the catalysis of an initiator, followed by a hydrolysis reaction in a dilute sodium hydroxide solution, and acidification with dilute hydrochloric acid to obtain 3-trifluoromethyl be...

AI Technical Summary

Problems solved by technology

The main shortcoming of above-mentioned method is: (1) raw material is difficult to obtain, and price is expensive, (2) hydrolysis reaction uses the sodium hydroxide solution (2.5 -10%); then use the very dilute hydrochloric acid (10%) of concentration to acidify and separate out 3-trifluoromethylbenzoic acid, thus causing a large amount of alkali, acid, water, and producing a large amount of waste water, thus It leads to high cost of industrialization, and at the same time creates a large burden on the process and wastewater treatment

[0005] The method reported by German patent (DE3813452, 1988) is to use m-ditrifluoromethylbenzene as a raw material, and reflux hydrolysis with 30% oleum of 1.3 moles to obtain 3-trifluoromethylbenzene with a yield of 66%. Formic acid; the shortcoming of this method is to produce a large amount of waste acid, and contain a large amount of hydrofluoric acid in the waste water liquid, strict to equipment material requirement, in addition the by-product m-dibenzoic acid that generates also influences product purity (product purity is 97.5%)

[0006] The cost of preparing 3-trifluoromethylbenzoic acid in the prior art is high, and a large amount of waste water and waste liquid are produced, which is not conducive to large-scale industrial production

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