Method for synthesizing 1-(2,4-dichlorophenyl)-3-methyl-4-difluoromethyl-1,2,4-triazole-5-ketone

Abstract

The invention discloses a method for synthesizing 1-(2,4-dichlorophenyl)-3-methyl-4-difluoromethyl-1,2,4-triazole-5-ketone. The method takes p-chloroaniline as a raw material, through diazotization, reduction, and salt forming, p-chlorophenylhydrazine hydrochloride is synthesized, p-chlorophenylhydrazine is obtained through alkali neutralization, under condition that tert-butyl alcohol is taken asa solvent, chlorophenylhydrazine, acetaldehyde, sodium cyanate and sodium hypochlorite are subjected to condensation, cyclisation and an oxidation reaction to generate 1-p-chlorophenyl-3-methyl-1H-1,2,4-triazole-5-ketone, and the 1-p-chlorophenyl-3-methyl-1H-1,2,4-triazole-5-ketone is subjected to salt forming, reaction with chlorodifluoromethane, and chlorination to obtain the 1-(2,4-dichlorophenyl)-3-methyl-4-difluoromethyl-1,2,4-triazole-5-ketone (a sulfentrazone intermediate). The synthetic method takes p-chloroanniline as the raw material, the synthetic method is realized by only one-time chlorination, steric hindrance for intermediate synthesis is small, and the impurity is low, so that the yield is increased; in addition, the raw materials required by the synthesis route are easilyacquired, the cost is low, the condition is mild, operation is simple, security is high, and the synthesis method is in favor of realizing industrial production.

Description

technical field [0001] The invention relates to the technical field of herbicide preparation, specifically a method for synthesizing 1-(2,4-dichlorophenyl)-3-methyl-4-difluoromethyl-1,2,4-triazole-5- The keto approach. Background technique [0002] Sulfentrazone is a low-toxic herbicide belonging to difluoromethyl triazolinones, a contact-killing stem and leaf treatment agent, especially effective against sulfonylurea-resistant weeds, and safe for subsequent crops , wide herbicidal spectrum, less dosage, fast herbicidal speed, suitable for corn, soybean, sorghum, peanut, sunflower and other crop fields, 1-(2,4-dichlorophenyl)-3-methyl- 4-Difluoromethyl-1,2,4-triazol-5-one is an intermediate in the synthesis of sulfentrazone, and its chemical structure is as follows: [0003] [0004] 1-(2,4-dichlorophenyl)-3-methyl-4-difluoromethyl-1,2,4-triazol-5-one is an intermediate for the synthesis of sulfentrazone, currently available in China There are many kinds of synthetic r...

AI Technical Summary

Problems solved by technology

[0005] People such as Zhang Yuanyuan disclosed the synthesis of the herbicide sulfentralam (the synthesis of the herbicide sulfentralam, Zhang Yuanyuan, etc., Pesticide Research and Application, No. 1, 2008) technology, the synthetic method uses 2,4-dichloro Aniline is used as the initial raw material, and diazotization, condensation, and N-alkylation are used to obtain the difluoromethyltriazolinone intermediate of sulfentrazone. The beneficial effects of the present invention are reflected in that the reaction raw materials are easy to obtain and the cost is low, and the reaction is mild , is conducive to industrial promotion; but there are certain shortcomings in this synthesis: using 2,4-dichloroaniline as a raw material, the intermediate product is prone to steric hindrance, high impurities, and low product yield

The beneficial effect of the present invention is reflected in: adopt o-chlorophenylhydrazine hydrochloride, the steric hindrance of intermediate product is little, and yield is high, but there is certain shortcoming in this method: reaction raw material trimethyl orthoacetate and potassium cyanate are not easy to get And the price is high, which increases the production cost; and the boiling point of dichloromethane is low, and the recovery loss is large

Images