Synthetic method of p-hydroxybenzonitrile

Abstract

The invention discloses a synthesis method of p-hydroxybenzonitrile, which comprises the following steps: carrying out diazotization reaction on p-hydroxyaniline to form a diazo compound, and reactingthe diazo compound with cuprous chloride and sodium cyanide to obtain the p-hydroxybenzonitrile. The p-hydroxyaniline is obtained by hydrogen reduction of p-nitrosophenol, and the p-nitrosophenol isobtained by nitrosation of phenol. The reaction temperature of each step is low, the reaction conditions are mild, and the reaction power consumption is greatly reduced. The reaction can be carried out by adopting a conventional reaction kettle, the equipment requirement is low, and the investment is small. According to the method, a dehydrating agent and filler are not used, only a small amount of catalyst is used, meanwhile, the catalyst can be recycled, the solid waste amount is small, only a small amount of solid catalyst is generated, and no difficult-to-treat wastewater is generated.

Description

technical field [0001] The invention relates to a synthesis method of p-hydroxybenzonitrile, in particular to a synthesis method of p-hydroxybenzonitrile with mild reaction conditions, low energy consumption and low cost, and belongs to the technical field of drug synthesis. Background technique [0002] p-Hydroxybenzonitrile, also known as 4-cyanophenol or p-cyanophenol, is an intermediate of the organophosphorus insecticides fenonitrile and benzonitrile, and an intermediate of the herbicide bromoxynil, and is also a liquid crystal material , spices and other intermediates. [0003] There are many synthetic methods of p-hydroxybenzonitrile, and the production methods are basically divided into the following types: (1) p-hydroxybenzoic acid method, using p-hydroxybenzoic acid, urea, dehydrating agent, and dehydration catalyst to uniformly disperse in an inert high-boiling point solvent , then react at high temperature, filter after the reaction, carry out vacuum distillatio...

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Problems solved by technology

[0004] CN109879778A discloses a synthetic method of p-hydroxybenzonitrile, which uniformly disperses substances such as p-hydroxybenzoic acid, urea, and catalyst in an inert high-boiling solvent , and then heated to 160 ° C ~ 220 ° C, one-step reaction after post-treatment to obtain p-hydroxybenzonitrile, crystallization to obtain p-hydroxybenzonitrile, the yield can reach 92.1-96.4%, but the reaction temperature is high and energy consumption is large , high equipment requirements; and the use of dehydrating agent phosphorus pentoxide, resulting in a large amount of phosphorus-containing solid waste, which limits its industrial production application

[0005] CN102249950B discloses a synthetic method of p-hydroxybenzonitrile, which dissolves p-hydroxybenzaldehyde and hydroxylamine hydrochloride in an organic solvent, and adds a large amount of tungsten-containing catalyst , control the reaction temperature at 80~140°C, and the reaction time is 8~12h, one-step synthesis of p-hydroxybenzonitrile, but the yield is only 61-91%. The reaction process uses a large amount of catalyst, which will generate a large amount of solid waste and is difficult to handle. , there is a serious problem of three wastes pollution

[0008] (1) Reaction under high temperature conditions, followed by rectification operation, high energy consumption

[0009] (2) Adopt fixed bed reactor, which requires high equipment and large investment

[0010] (3) The use of dehydrating agents, fillers, and catalysts will generate a large amount of solid waste