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Preparation method of 2-amino-4-methylbenzothiazole

A technology of methylbenzothiazole and o-methylphenylthiourea, which is applied in the field of preparation of agricultural compounds, can solve the problems of narrow reaction temperature range, difficult treatment, and large alkali consumption, so as to reduce the difficulty and risk of operation and the amount of waste liquid The effect of reducing and reducing the amount of waste liquid

Active Publication Date: 2018-09-21
浙江禾本科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, its main synthesis method is to use the method of chlorine gas cyclization. Although the yield of this method reaches about 90%, it needs to add excessive chlorine gas, and chlorine gas is more toxic and difficult to handle.
It has recently been reported that the use of concentrated sulfuric acid as a solvent and sodium bromide as a catalyst to realize the one-pot synthesis of 2-amino-4-methylbenzothiazole, but this method sodium bromide needs to be added in batches at a specific temperature, sodium bromide Adding too fast will reduce the reaction yield, and the reaction temperature range is narrow, if the temperature is too low, it will not react, if the temperature is too high, it will be easily carbonized, and the reactant is in concentrated sulfuric acid, which brings potential risks to the operation, and the biggest problem After the reaction is completed, the post-treatment adopts directly pouring concentrated sulfuric acid into a large amount of water to precipitate sulfate, and then adjusts the system to weak alkaline with alkali. Since there is a large amount of sulfuric acid in the system, this process not only has a low utilization rate of sulfuric acid , and need to consume a large amount of alkali to neutralize sulfuric acid, and produce a large amount of waste water

Method used

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  • Preparation method of 2-amino-4-methylbenzothiazole

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] Embodiment 1: Preparation of 2-amino-4-methylbenzothiazole

[0061] The implementation steps of this embodiment are as follows:

[0062] A. Ring closure reaction

[0063] According to the mass ratio of the total mass of acetic acid and sulfuric acid to o-methylphenylthiourea 4.5:1 and the mass ratio of acetic acid to sulfuric acid 0.8:1.0, add o-methylphenylthiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and slowly heat to a temperature of 75°C, and at the same time send the escaped tail gas containing sulfur dioxide to the acetic acid sulfuric acid concentrate in step B, then add a sodium bromide catalyst according to the mass ratio of sodium bromide to o-methylphenylthiourea 0.03:1.0, and mix well , react at a temperature of 75° C. for 3 hours to obtain a 2-amino-4-methylbenzothiazole solution;

[0064] B. Filtration and washing

[0065] The temperature of the 2-amino-4-methylbenzothiazole solution obtained in step A is lowered to room t...

Embodiment 2

[0071] Embodiment 2: Preparation of 2-amino-4-methylbenzothiazole

[0072] The implementation steps of this embodiment are as follows:

[0073] A. Ring closure reaction

[0074] According to the mass ratio of the total mass of acetic acid and sulfuric acid to o-methylphenylthiourea 3:1 and the mass ratio of acetic acid to sulfuric acid 0.3:1.0, add o-methylphenylthiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and slowly heat to a temperature of 84°C, and at the same time send the escaped tail gas containing sulfur dioxide to the concentrated solution of acetic acid and sulfuric acid in step B, then add a sodium bromide catalyst according to the mass ratio of sodium bromide to o-methylphenylthiourea 0.01:1.0, and mix well , react at a temperature of 95° C. for 1 h to obtain a 2-amino-4-methylbenzothiazole solution;

[0075] B. Filtration and washing

[0076] The temperature of the 2-amino-4-methylbenzothiazole solution obtained in step A is lowere...

Embodiment 3

[0082] Embodiment 3: Preparation of 2-amino-4-methylbenzothiazole

[0083] The implementation steps of this embodiment are as follows:

[0084] A. Ring closure reaction

[0085] According to the mass ratio of the total mass of acetic acid and sulfuric acid to o-methylphenylthiourea 5:1 and the mass ratio of acetic acid to sulfuric acid 1.0:1.0, add o-methylphenylthiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and heat slowly to a temperature of 100°C, and at the same time send the escaped tail gas containing sulfur dioxide to the acetic acid sulfuric acid concentrate in step B, then add a sodium bromide catalyst according to the mass ratio of sodium bromide to o-methylphenylthiourea 0.06:1.0, and mix well , reacted at a temperature of 82°C for 2.4h to obtain a 2-amino-4-methylbenzothiazole solution;

[0086] B. Filtration and washing

[0087] The temperature of the 2-amino-4-methylbenzothiazole solution obtained in step A is lowered to room tempe...

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Abstract

The invention relates to a preparation method of 2-amino-4-methylbenzothiazole. The preparation method comprises the steps of cyclization reaction, filtering and washing, recycling and the like. By the method, operation risks are reduced, the utilization rate of sulfuric acid is increased, zero emission of gas is realized basically, the emission amount of waste water is reduced effectively, and thus, the yield of synthesis is stable.

Description

【Technical field】 [0001] The invention relates to the technical field of preparation of agricultural compounds. More specifically, the present invention relates to a preparation method of 2-amino-4-methylbenzothiazole. 【Background technique】 [0002] 5-Methyl-1,2,4-triazolo[3,4-b]-benzothiazole (tricyclazole) is a high-efficiency, systemic azole fungicide, which has special effects on the control of rice blast, It is also effective against blast fungus resistant to other fungicides. Among them, 2-amino-4-methylbenzothiazole is one of the important intermediates for the synthesis of pesticide tricyclazole, which is obtained by cyclization of N-o-tolylthiourea. At present, its main synthesis method is the method of using chlorine gas cyclization. Although the yield of this method reaches about 90%, it needs to add excess chlorine gas, which is more toxic and difficult to handle. It has recently been reported that the use of concentrated sulfuric acid as a solvent and sodium...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D277/82
CPCC07D277/82
Inventor 徐齐恩潘光飞王亚洲王进戴光炳陈云南李成斌
Owner 浙江禾本科技股份有限公司
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