Process for continuously synthesizing 2-hydroxy-benzonitrile by phosgene method

Abstract

The invention relates to a process for continuously synthesizing 2-hydroxy-benzonitril by a phosgene method, which comprises the following steps: injecting a hot-melt salicylamide xylene solution into a photochemical tower filled with filler from the upper part, enabling a reaction solution to overflow into a degassing tower through a U-shaped balance pipe at the bottom, additionally arranging an online analyzer on the U-shaped balance pipe, and controlling the feeding ratio of salicylamide to phosgene in an interlocking manner. After degassing by a degassing tower is qualified, obtaining 2-hydroxy-benzonitril feed liquid, and enabling tail gas to pass through a phosgene destroying device, so as to complete up-to-standard treatment. The average yield of 2-hydroxy-benzonitrile continuously synthesized by the phosgene method exceeds 99.6%, and the method has the characteristics of high conversion rate, few impurities, greatly reduced online photochemical materials and obviously improved intrinsic safety, and is suitable for industrial production.

Description

technical field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a process for continuously synthesizing salicylonitrile by a phosgene method. Background technique

[0002] Salicylic nitrile, molecular weight 119.12, white crystal with special odor. It is miscible in DMF and sodium hydroxide solution, and can be used as the key intermediate of bunilol, azoxystrobin and other products, as well as the intermediate of many fragrances and liquid crystal materials.

[0003] At present, the generation methods of salicylonitrile mainly include: salicylaldoxime dehydration method, salicylamide dehydration method, o-hydroxyhalobenzene cyanide method, ammonium salicylate method, ammonia oxidation method, thionyl chloride, phosgene method, etc. Among them, the salicylaldoxime dehydration method and the salicylamide dehydration method use more toxic raw materials as the dehydrating agent, and produce a large amount of acidic wastewa...