Synthesis process of 2,4,6-trimethyl benzoic acid

Abstract

The present invention belongs to the field of refined chemical preparation, and is especially process of synthesizing 2, 4, 6-trimethyl benzoic acid. Compound 2, 4, 6-trimethyl benzoic acid may be used as intermediate for dye, pesticide, medicine and photoinitiator, and to synthesize trimethyl benzoyl chloride, hardening agent for polyepoxide and photoinitiator for polymer. The synthesizing process includes the following steps: 1. acylation reaction of sym-trimethyl benzene and chloroacethyl chloride via heating in the presence of acylating catalyst and subsequent filtering and acidifying the filtrate to prepare 2, 4, 6-trimethyl chloro acetophenone; 2. chloroform reaction of the product of the step 1 and sodium hypochlorite via heating in the presence of quaternary ammonium salt as phase transfer catalyst to prepare 2, 4, 6-trimethyl benzoic acid; and 3. hydrolysis reaction of the product of step 2 and subsequent extraction, acid neutralization and re-crystallization.

Description

technical field [0001] The invention belongs to the field of preparation technology of fine chemicals, in particular to a synthesis technology of 2,4,6-trimethylbenzoic acid. 2,4,6-Trimethylbenzoic acid can be used as an intermediate of dyes, insecticides, medicines and photoinitiators; it can be used to synthesize trimethylbenzoyl chloride, hardener of polyepoxide and photoinitiator of polymers agent etc. Background technique [0002] The methods for the production of 2,4,6-trimethylbenzoic acid in early reports mainly include nitric acid oxidation of tetramethylene as raw material, dry distillation of 2,4,6-trimethylmandelic acid, mesitylene and carbamoyl chloride as The acylation method of raw materials, sulfuric acid treatment 2,4,6-trimethylphenylglyoxal acidification method, etc. all have not been practically applied due to the use of special raw materials, some technical difficulties, and low product yields. [0003] In recent years, researchers have tried to produc...

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Problems solved by technology

[0002] The methods for the production of 2,4,6-trimethylbenzoic acid in early reports mainly include nitric acid oxidation of tetramethylene as raw material, dry distillation of 2,4,6-trimethylmandelic acid, mesitylene and carbamoyl chloride as The acylation method of raw materials, sulfuric acid treatment of 2,4,6-trimethylphenylglyoxal acidification method, etc., but because of the use of special raw materials, some technical difficulties are large, and the product yield is low, so they have not been practically applied

[0003] In recent years, researchers have tried to produce 2,4,6-trimethylbenzoic acid with mesitylene as raw material, mainly mesitylene and chloroacetyl chloride as reaction raw materials, and the Friedrich reaction catalyst used is usually aluminum trichloride. A large amount of sour gas is produced in the reaction and aftertreatment process, and the equipment is severely corroded. There are also acylation reactions using iron oxide as a catalyst, and the chloroform reaction that is carried out by using it. The content in this respect is mainly described in (US5,296,636 and Lv Jiuzhuo, 2,4,6,-Synthesis of trimethylbenzoic acid, fine petrochemical industry, 2001.3 journal), but the usual iron oxide is in powder form, it is difficult to separate from the product in the organic synthesis reaction process, and makes the product Contains a large amount of iron, it is difficult to guarantee the quality of the product

And powdery iron oxide is difficult to realize the continuous organic synthesis operation, makes production efficiency low

On the other hand, adopt high pollutant Cl 2 As a raw material for chloroform reaction, it makes the operation difficult and increases the degree of harm