Synthetic method for 4-chlorophenylhydrazine hydrochloride

Abstract

The invention discloses a synthetic method for 4-chlorophenylhydrazine hydrochloride. The synthetic method comprises the following steps: 4-bromochlorobenzene and hydrazine hydrate are taken as reaction raw materials, and a phase transfer catalyst, a solvent and a catalyst are added for a reaction; after the reaction, solids are filtered and separated, and a solvent is removed from a filtrate through distillation; hydrochloric acid is added to residues obtained after distillation, and the mixture is stirred and filtered; filter residues are washed with water and dried, and 4-chlorophenylhydrazine hydrochloride is obtained. The synthetic method aims to solve the problem of generation of a large amount of wastewater due to adoption of a current commonly used method for reduction acidification after diazotization of 4-chloroaniline, 4-bromochlorobenzene and hydrazine hydrate are taken as the reaction raw materials, the phase transfer catalyst, the solvent and the catalyst are added for the reaction, the reaction steps are simple, the wastewater produced in a 4-chlorophenylhydrazine synthetic method is reduced remarkably, sulfur dioxide is prevented from being produced through reduction of sodium sulfite, excessive hydrazine hydrate and solvent can be recovered and reused after reaction, and the method is environment-friendly.

Description

technical field [0001] The invention relates to a synthesis method of p-chlorophenylhydrazine hydrochloride, in particular to a method for synthesizing pyraclostrobin intermediate p-chlorophenylhydrazine hydrochloride, and belongs to the field of organic compound synthesis. Background technique [0002] p-Chlorophenylhydrazine, the molecular formula is C 6 h 7 ClN 2 , the structural formula is , is an important synthetic intermediate of pyraclostrobin, obtained from p-chloroaniline through diazotization, sodium bisulfite reduction, and hydrolysis, and this method has been used for a long time. For example: [0003] Patent document CN104926682A (a preparation method of p-chlorophenylhydrazine hydrochloride, 2015.09.23) discloses that p-chloroaniline is used as a raw material, and after diazotization and reduction, the non-polar solvent toluene or benzene, dichloromethane , chloroform, and dichloroethane to extract the water phase to remove impurities, then add hydrochlo...

AI Technical Summary

Problems solved by technology

[0008] In order to solve a large amount of wastewater problems and potential safety hazards caused by the reductive acidification method after the commonly used p-chloroaniline diazotization, the invention provides a new synthetic method of p-chlorophenylhydrazine hydrochloride. Bromochlorobenzene and hydrazine hydrate are used as raw materials for the reaction, and the reaction is carried out after adding a phase transfer catalyst, a solvent, and a catalyst. A large amount of acid is used, the solvent and excess hydrazine hydrate can be recycled, and the catalyst is returned to the reaction system after simple treatment. The whole process does not generate harmful gases and is environmentally friendly.