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A kind of 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 problems such as narrow reaction temperature range, difficult handling, and large alkali consumption, so as to reduce operation difficulty and risk and improve fluidity , The effect of reducing the amount of waste liquid

Active Publication Date: 2020-05-12
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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  • A kind of preparation method of 2-amino-4-methylbenzothiazole
  • A kind of preparation method of 2-amino-4-methylbenzothiazole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] Example 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-toluidine thiourea of ​​4.5:1 and the mass ratio of acetic acid to sulfuric acid of 0.8:1.0, add o-tolyl thiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and heat slowly to a temperature of 75°C, while the escaping tail gas containing sulfur dioxide is sent to the concentrated acetic acid sulfuric acid of step B, then a sodium bromide catalyst is added according to the mass ratio of sodium bromide and o-methylphenylthiourea 0.03:1.0, and the mixture is uniform , and reacted at 75°C for 3h to obtain 2-amino-4-methylbenzothiazole solution;

[0064] B. Filtration and washing

[0065] The temperature at which the 2-amino-4-methylbenzothiazole solution was obtained in step A was lowered to room tem...

Embodiment 2

[0071] Example 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-toluene thiourea of ​​3:1 and the mass ratio of acetic acid to sulfuric acid of 0.3:1.0, add o-tolyl thiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and heat slowly to a temperature of 84°C, while the escaping sulfur dioxide-containing tail gas is sent to the concentrated acetic acid sulfuric acid solution of step B, then a sodium bromide catalyst is added according to the mass ratio of sodium bromide to o-methylphenylthiourea 0.01:1.0, and the mixture is uniformly mixed. , and reacted for 1 h at a temperature of 95 °C to obtain a 2-amino-4-methylbenzothiazole solution;

[0075] B. Filtration and washing

[0076] The temperature at which the 2-amino-4-methylbenzothiazole solution was obtained...

Embodiment 3

[0082] Example 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-toluidine thiourea of ​​5:1 and the mass ratio of acetic acid to sulfuric acid of 1.0:1.0, add o-tolyl thiourea and sulfuric acid to the acetic acid solvent, stir and mix evenly, and heat slowly to a temperature of 100 ° C, while the escaping sulfur dioxide-containing tail gas is sent to the concentrated acetic acid sulfuric acid of step B, and then a sodium bromide catalyst is added according to the mass ratio of sodium bromide and o-methylphenylthiourea 0.06:1.0, and mix homogeneously , and reacted at a temperature of 82 ° C for 2.4 h to obtain a 2-amino-4-methylbenzothiazole solution;

[0086] B. Filtration and washing

[0087] The temperature at which the 2-amino-4-methylbenzothiazole solution was obtained in step A...

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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 present 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 highly efficient and systemic azole fungicide with special effects on the control of rice blast. It is also effective against M. oryzae that produces antibodies to other fungicides. Among them, 2-amino-4-methylbenzothiazole is one of the important intermediates in the synthesis of pesticide tricyclazole, which is obtained by cyclizing N-o-tolylthiourea. At present, its main synthesis method is the method of using chlorine gas cyclization. Although this method has a yield of about 90%, it needs to add excess chlorine gas, and chlorine gas is highly toxic and difficult to handle. Recently reported using concentrated sulfuric acid as a solvent, and using so...

Claims

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Application Information

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Patent Type & Authority Patents(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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