Preparation process of 2-tolylhydrazine hydrochloride

Abstract

The invention relates to a preparation process of 2-tolylhydrazine hydrochloride, which comprises the following steps of: firstly, carrying out a diazo reaction on o-nitrotoluene as an initial raw material to obtain benzenediazonium chloride; secondly, further carrying out a reducing reaction on the benzenediazonium chloride obtained in the first step under the action of a reducing agent to obtain a reduzate; and thirdly, carrying out a hydrolytic reaction on the reduzate obtained in the second step under the action of hydrochloric acid to generate the 2-tolylhydrazine hydrochloride. Particularly, in the second step, sodium metabisulfite is used as the reducing agent in the reducing reaction; and the reducing reaction is carried out under the conditions that the temperature is 15-25DEG C and the pH value is 7-9. According to the method, the production period can be shortened and the production cost is reduced while high yield is obtained.

Description

technical field [0001] The invention relates to a preparation method of phenylhydrazine hydrochloride, in particular to a preparation process of 2-methylphenylhydrazine hydrochloride. Background technique [0002] 2-Methylphenylhydrazine hydrochloride is an important intermediate, mainly used to prepare indole and pyrazolone derivatives, and can also be used to prepare other chemical products. The traditional preparation process of 2-methylphenylhydrazine hydrochloride includes two-step process of diazotization of aniline and reduction of benzene diazonium chloride, wherein the diazotization of aniline is mostly in hydrochloric acid medium, under the condition of pH equal to 2, at 0 Sodium nitrite is added to react at a low temperature of ~5°C to generate benzenediazonium chloride. Sodium sulfite and sodium bisulfite are generally used as reducing agents for the reduction of diazobenzene chloride, and ammonium bisulfite and ammonium hydroxide are also used as reducing agent...

AI Technical Summary

Problems solved by technology

The synthetic method of this traditional phenylhydrazine hydrochloride, the reaction time is as long as 3~4 hours, and the yield is only between 63~72%. In addition, when the reducing agent used is sodium sulfite, the cost is higher, and the Production cost; and when ammonium bisulfite and ammonium hydroxide are used as reducing agents, because they are liquid, it is not easy to transport and store

In addition, reduction kettle, pressure filter and acid analysis kettle are used in this process, which requires a lot of equipment and large investment.