Method for preparing 2-cyanophenol

Abstract

The invention discloses a method for preparing 2-cyanophenol, which comprises the following steps: preparing salicylaldoxime; performing dehydration; and performing hydrolytic-acidification reaction, wherein in the dehydration, anhydride is adopted as a dehydrating agent; and in the hydrolytic-acidification reaction, a hydrolyticreagent is 10 to 30 mass percent alkaline solution, and the temperature of the hydrolytic-acidification reaction is 100 to 150DEG C. The preparation method comprises three steps of preparing the salicylaldoxime; performing dehydration; and performing hydrolytic-acidification reaction; the operation in each step is easy and feasible; the product generated in the third step is not needed to be recrystallized, the purity can reach over 95 percent and the total yield can reach over 92 percent; the process flow is simple, the product is easily produced industrially and the equipment cost is low; besides, the raw materials and auxiliary materials used in the invention are conventional chemical reagents, the varieties are single, and partial solvents can be recycled, so the problems of large wastewater quantity, high price of the dehydrating agent, potential safety hazard, high recrystallization cost and the like in the prior art are solved.

Description

Technical field [0001] The invention relates to a preparation method of o-hydroxybenzonitrile, in particular to a preparation method for synthesizing o-hydroxybenzonitrile by using salicylaldehyde and hydroxylamine hydrochloride as raw materials. Background technique [0002] O-Hydroxybenzonitrile is an important intermediate for pesticides, fragrances, liquid crystal materials, etc., especially the key intermediate for the synthesis of methoxy acrylate fungicide azoxystrobin. It is widely used in agrochemicals, pharmaceutical chemicals and other industries Applications. There are well-known techniques for the preparation of o-hydroxybenzonitrile, and there are mainly two synthetic routes, respectively, which use salicylamide and salicylaldehyde as raw materials to synthesize o-hydroxybenzonitrile. Among them, the preparation of o-hydroxybenzonitrile by dehydration with salicylamide as a raw material is a promising process. There have been a large number of reports in the litera...

AI Technical Summary

Problems solved by technology

Wherein taking salicylamide as raw material to prepare o-hydroxybenzonitrile through dehydration is a promising process route, which has been reported in a large number of documents, but under the premise of achieving a better dehydration effect, the dehydrating agent used is either expensive, Or the problem of safety and environmental protection is serious, therefore, the selection of dehydrating agent has restricted the industrialized production of this method

CN94191224.8 describes the reaction between salicylaldehyde and hydroxylamine, and then dehydrates the generated salicylaldoxime to prepare o-hydroxybenzonitrile. This method needs to prepare metal salts or complexes of salicylaldehyde in advance, and the process flow is long and the operation is cumbersome. , and the amount of organic wastewater is large

The method for preparing salicylaldoxime from salicylaldehyde was reported earlier by Welcher F J (New York: DVan Nostrand Co., 259, 1947) and Windholz Marthz (Rahway (New Jesey): Merk & Co., Inc., 8296, 1988) A method for preparing salicylaldoxime from salicylaldehyde, sodium hydroxide solution, and hydroxylamine hydrochloride. This reaction is carried out under alkaline conditions, which is unfavorable for the condensation reaction of salicylaldehyde and hydroxylamine; and salicylaldehyde is easily deteriorated when heated under alkaline conditions. , will reduce product quality. In addition, the post-treatment of this method requires crystallization and recrystallization of benzene and a mixed solution of benzene and petroleum ether. The use of highly toxic solvent benzene is its fatal shortcoming; moreover, the method is cumbersome to operate and the yield is low High, and the product is slightly red, affecting subsequent use