Preparation process for 4-trifluoromethoxy

Abstract

The invention relates to a preparation process for 4-trifluoromethoxy. The preparation process comprises the followings steps of: (1) undergoing a nitridation reaction on o-toluidine serving as a starting raw material to obtain benzene diazonium chloride; (2) further undergoing a reduction reaction on the benzene diazonium chloride obtained in the step (1) under the action of a reducing agent to obtain a reduction product; and (3) undergoing a hydrolysis reaction on the reduction production obtained in the step (2) under the action of hydrochloric acid to generate 2-procarbazine hydrochloride, wherein particularly, in the step (2), the reduction reaction is undergone by taking sodium pyrosulfite as a reducing agent under the condition that the temperature is 15-25 DEG C and the pH is 7-9. A method disclosed by the invention has high yield, production period can be shortened, and production cost is lowered simultaneously.

Description

technical field [0001] The invention relates to a preparation process of 4-trifluoromethoxy, in particular to a preparation process of 4-trifluoromethoxy. 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 agents. The reduced phenylhydrazin...

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.