Preparation method of salicylonitrile

Abstract

The invention provides a preparation method of salicylonitrile. The preparation method comprises the following steps: (1) reacting thionyl chloride with a salicylamide solution to generate a salicylonitrile crude product; and (2) supplementing thionyl chloride into the salicylonitrile crude product, cooling and crystallizing to obtain salicylonitrile. The preparation method is simple in process and high in safety, the reaction process is easy to control, and few impurity byproducts are generated in the reaction; particularly, a crude product post-treatment method is simple and convenient, andthe separation and purification efficiency is high; the preparation method is simple, the yield and purity of the obtained salicylonitrile are high, the mass percentage content of salicylamide in thesalicylonitrile product is effectively controlled to be lower than 0.5%, the purity of the salicylonitrile is up to 95% or above, a large amount of industrial wastewater cannot be generated, and the preparation method is an environment-friendly, simple and efficient preparation process of the high-purity salicylonitrile.

Description

technical field [0001] The invention belongs to the technical field of organic compound preparation, and in particular relates to a preparation method of salicylonitrile. Background technique [0002] Salicylonitrile, or o-hydroxybenzonitrile, is an important chemical intermediate for the synthesis of liquid crystal materials, spices, pesticides, etc., especially the key intermediate for the synthesis of methoxyacrylate fungicides, such as azoxystrobin. Chemicals, pharmaceutical chemicals, polymer materials, dyes, organic synthesis and other industrial fields have a wide range of applications. [0003] The preparation method of salicylonitrile that has been reported at present is mainly divided into two kinds, and one is synthesized with salicylaldehyde as raw material, and the other is dehydrated to generate salicylonitrile with salicylamide as raw material. Wherein the preparation method using salicylaldehyde as a raw material needs to first react salicylaldehyde and hydr...

AI Technical Summary

Problems solved by technology

[0007] However, in the existing salicylonitrile preparation technology, although the dehydrating agent phosgene has high reactivity, phosgene is a highly toxic gas, which is dangerous in production and difficult to operate; Side reactions such as carbonylation and cyclocondensation occur with nucleophiles containing C, N, and O atoms, and the requirements for reaction conditions are relatively high

Although the preparation method using a solid catalyst avoids highly toxic dehydrating agents, the post-reaction treatment requires the use of a large amount of organic solvents such as benzene for crystallization and recrystallization, resulting in high waste liquid treatment costs

Triphosgene is a solid-phase substitute of phosgene, which can react with salicylamide to generate salicylonitrile, but the residual amount of salicylamide in the product obtained by this method is higher, which can reach 3%, which seriously affects the production of salicylamide. Subsequent use especially affects the product yield and purity when salicylonitrile is used to prepare azoxystrobin; the method of repeated washing with acid solution and lye is commonly used in industry to remove salicylamide in salicylonitrile, but this method will produce a large amount of Difficult to handle industrial waste liquid, causing environmental pollution

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