One-step synthetic method of p-(o-)hydroxybenzonitrile

Abstract

The invention discloses a one-step synthetic method of p-(o-)hydroxybenzonitrile. The one-step synthetic method comprises the following steps: dissolving methyl p-(o-)hydroxybenzoate in an organic solvent, and then putting dissolved methyl p-(o-)hydroxybenzoate together with free ammonia into a catalyst-loaded fixed bed reactor a through a pipeline to synthesize p-(o-)hydroxybenzonitrile through one step under the conditions that the reaction temperature is 250-550 DEG C and the reaction pressure is 0-1.0Mpa, wherein the mass ratio of the free ammonia to the methyl p-(o-)hydroxybenzoate is (2-10):1, the space velocity for the free ammonia and the methyl p-(o-)hydroxybenzoate to enter the fixed bed reactor together is 0.5-5.0h<-1>, and the catalyst is obtained by kneading active components including P2O5, CuO, SnO and MoO3 with a carrier. The method disclosed by the invention adopts a production form with the fixed bed reactor, is more suitable for continuous production, and avoids complexity of an original intermittent reaction process and cumbersome reaction operation, and the production capacity is greatly improved; and meanwhile, the use level of the free ammonia is relatively low, so that excessive free ammonia can also be recycled after gas-liquid separation, the method is further improved in cost saving and environmental protection.

Description

technical field [0001] The invention relates to a synthesis method of p-(o)hydroxybenzonitrile, in particular to a one-step synthesis method of p-(o)hydroxybenzonitrile, which belongs to the technical field of chemical industry. Background technique [0002] p-Hydroxybenzonitrile, also known as p-cyanophenol, p-hydroxybenzonitrile, etc., is an extremely important fine organic chemical raw material and intermediate, widely used in the synthesis of various medicines, spices, pesticides, liquid crystal materials and buffers Agents, etc., especially as pesticide intermediates, can be used to synthesize a variety of pesticides such as "fenonitrile", "benzonilphos", "bromoxynil", "hydroxychlorenil" and "chlorothalonil". With the development of my country's agricultural modernization, the demand for pesticides has increased significantly, and the demand for p-hydroxybenzonitrile has also increased significantly. O-hydroxybenzonitrile, also known as salicylonitrile, can be used to ...

AI Technical Summary

Problems solved by technology

[0003] There are many synthetic methods of hydroxybenzonitrile, which can be divided into hydroxybenzoic acid dehydration ammoniation method, hydroxybenzaldehyde ammoniation method, diazonium salt method, p-cresol method and p-cresol sodium method according to different raw materials: Benzoic acid dehydration ammonification method usually obtains p-hydroxybenzonitrile by ammoxidation reaction of p-cresol in a fluidized bed. Although the process adopts a fluidized bed continuous reaction, under the reaction conditions, a higher The reaction temperature obtains a lower p-hydroxybenzonitrile yield, and the yield is only 50 to 65%, and the unsafety of the reaction system is increased due to the existence of oxygen in the reaction process

Hydroxybenzaldehyde ammonification method adopts p-hydroxybenzaldehyde and hydroxylamine hydrochloride to prepare p-hydroxybenzonitrile under the effect of tungsten catalyst, but in this reaction process, the catalyst consumption is too large, which is about 9% of the raw material p-hydroxybenzaldehyde amount times, and the reaction process is slow; at the same time, the most important thing is that the process adopts the batch reaction form, which further restricts the large-scale production requirements

The diazonium salt method, the p-cresol method and the sodium p-cresol method, etc. basically adopt a batch reaction, which is not suitable for large-scale continuous production, and the reaction pressure is also high, which increases the investment in equipment; in addition, the reaction There are many steps and complicated operation process, which limits the large-scale production of p-hydroxybenzonitrile

Images