Preparation method of florasulam

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of florasulam. According to the method, 8-fluoro-5-methoxy- [1,2,4] triazolo [1,5-C ] pyrimidine-2-sulfonyl chloride and 2, 6-difluoroaniline are used as reaction raw materials, 3-aminopyridine is used as an acid-binding agent, the condensation reaction is carried out in the presence of dichloroethane as a solvent, after the condensation reaction is finished, the temperature is reduced, the filtration and the drying are carried out to obtain the florasulam, the reaction yield can reach more than 98.5%, the use amount of the 2, 6-difluoroaniline with higher price in the prior art can be greatly reduced, the production cost is greatly reduced while the yield is higher, and a high-purity product can be obtained.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of florasulam. Background technique [0002] Flusulam is a triazolopyrimidine sulfonamide herbicide developed by Dow Agricultural Sciences Company of the United States. It is an ultra-efficient herbicide for post-emergence stem and leaf treatment of broad-leaved weeds in wheat fields. The agent has good long-lasting effect , wide herbicidal spectrum, stable efficacy at low temperature, it has been widely used abroad, since it was put into the domestic wheat field herbicide market, it is deeply loved by wheat farmers and paid attention to by pesticide manufacturers. [0003] Patent WO9937650A1 discloses two preparation methods of florasulam, one is to react only in the presence of 1,2-propanediol, and the yield is 88.9%; the other is to react simultaneously with 1,2-propanediol and naphthalene catalyst In the presence of reaction, the yi...

AI Technical Summary

Problems solved by technology

Although the latter method has a higher yield, it uses a naphthalene catalyst, which greatly increases the production cost, and the method uses multiple amounts of 2,6-difluoroaniline, and the excess 2,6-difluoroaniline cannot be recycled, resulting in higher production costs

Patent CN103509027A discloses a preparation method of florasulam. Although the yield of this method is high, the reproducibility of the method is poor, and the requirements for the proportion of materials, reaction temperature and reaction time are relatively high, and impurities are easily generated

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