Method for preparing pesticide nitenpyram

Abstract

The invention relates to a method for synthesizing a pesticide, and in particular relates to a method for preparing a pesticide nitenpyram. The method for preparing the pesticide nitenpyram is characterized in that 1, 1, 1, 2-trichloroethane is taken as a starting material, and an intermediate of 1, 1, 1-trichloro-2-nitroethane is directly synthesized through elimination reaction and catalytical nitration reaction; 2, 2-chloro-5-nitrapyrin is taken as a staring material, water is taken as solvent, a phase-transfer catalysis technology is adopted, and an intermediate of N-ethyl-2-chloro-5-pyridyl methyl amine is obtained through N-alkylation reaction; and 3, the two intermediates are mixed together, dichloromethane with low toxicity is taken as the solvent, condensation and methyl amination reaction are carried out in a same reaction vessel, and the nitenpyram is produced through extracting, desolventizing and crystallizing. The method for preparing the pesticide nitenpyram has high product yield and purity and a short technological process. Compared with the prior art, the method has the advantages of high total yield, low cost, high product purity, less environmental pollution, benefits for industrial production and the like.

Description

technical field [0001] The invention relates to a method for synthesizing insecticides, in particular to a method for preparing nitenpyram with 1,1,2-trichloroethane and 2-chloromethylpyridine as main raw materials. Background technique [0002] Nitenpyram is a new generation of neonicotinoid insecticides following imidacloprid, and its molecular structure is: [0003] [0004] It is the latest domestically popularized new variety to replace highly toxic organophosphorus pesticides. It has unique chemical and biological properties and has a nerve-blocking effect on synaptic receptors of pests. It is effective against various aphids, whiteflies, rice leafhoppers and thistles. Horses and others have shown excellent activity, and have the advantages of high efficiency, low toxicity, environmental safety, high systemicity, no cross-resistance, and no phytotoxicity to crops. crop pests. In particular, this product has a lore killing effect on SBPH and BPH. It takes about 10 ...

AI Technical Summary

Problems solved by technology

Many problems were encountered in the test: the preparation process of the intermediate 1,1-dimethylthio-2-nitroethylene is complex, and it is toxic and has an unpleasant odor. There are complex process flow, unsafe operation, pollution of the environment, Disadvantages such as high cost; ② using documented technology to prepare 1,1,1-trichloro-2-nitroethane with industrial hydrochloric acid and nitric acid, and then react with N-ethyl-2-chloro-5-picolylamine In the route of nitration, there is too much acid in the nitrification process, the waste acid is difficult to handle, and the environmental pollution is serious

In the preparation process of the intermediate N-ethyl-2-chloro-5-picolylamine, a large amount of solvent is used, but the yield is not high, the recovery of the solvent is difficult, the cost is high, and the environment is greatly polluted

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