Preparation method of 4-methyl-2-amino benzothiazole

Abstract

The invention discloses a preparation method of 4-methyl-2-amino benzothiazole. O-tolylthiourea as a raw material is dissolved in an organic solvent, and Cl2 is used as a cyclization reagent for reaction. The method is characterized by comprising the following steps: reacting at 0-50 DEG C, introducing chlorine at a speed 0.05-1.0 time / h of the mole number of the raw material in the reaction process; when 1-10% of the unreacted material is left, stopping chlorine introduction to terminate the reaction; and conducting post-treatment and separation on the reaction solution to obtain the product, and recycling and reusing the solvent and unreacted material. The preparation method provided by the invention has good reaction selectivity and simple operation process, and is suitable for industrialized production; the product has high yield and good quality, fully meets the requirements for production of high-quality agricultural fungicide tricyclazole; and the unreacted material is effectively recycled and utilized to reduce raw material consumption and reduce three waste emissions.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a method for preparing 4-methyl-2-aminobenzothiazole. Background technique [0002] 4-Methyl-2-aminobenzothiazole is an important intermediate of the agricultural fungicide tricyclazole, which has been widely used in countries all over the world. In recent years, customers at home and abroad have continuously increased the quality requirements for the technical tricyclazole fungicide (the content is not less than 95% or even 98%), and the quality of its intermediates directly affects the quality of the final product, so high quality must be obtained in industrial production. Quality 4-methyl-2-aminobenzothiazole. [0003] There have been many reports on the synthesis of 4-methyl-2-aminobenzothiazole by ring-closing reaction using o-methylphenylthiourea as the main raw material. The main difference lies in the different ring-forming reagents used. Gupta et al. (Journ...

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Problems solved by technology

[0004] In the above-mentioned o-toluenethiourea ring-closure reaction, when the ring-forming reagent used is SOCl 2 , concentrated H 2 SO 4 or bromine, the three wastes produced in industrial production are more, which cannot meet the requirements of green and clean production

In the presence of catalytic amount of bromine, cheap Cl 2 When used as a ring forming agent, the resulting product still does not meet the requirements for preparing high-quality tricyclazole; use Cl alone 2 As a ring forming agent, when no catalyst is used, the product yield is less than 90%

Thereby prior art is difficult to obtain the 4-methyl-2-aminobenzothiazole of high quality, high yield

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