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

A salicylonitrile and phosgene technology, applied in the chemical industry, can solve the problems of large online amount of photochemical materials, limit industrial application, and low production efficiency, and achieve low raw material consumption, stable product quality, and reduced online amount.

Pending Publication Date: 2022-08-05
JIANGSU CHANGLONG AGROCHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The reaction is a batch reaction, the online amount of photochemical materials is large, the synthesis temperature is high (170°C-175°C), the safety risk is large, and the production efficiency is low, which limits its industrial application

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The mass ratio of the salicylamide xylene solution to the salicylamide xylene solution is 1:5, and the temperature of the salicylamide xylene solution is kept at 100° C. through a solid automatic feeder and a solvent metering pump. The salicylamide xylene solution was injected from the top into the synthesis tower equipped with packing, and phosgene was introduced from the bottom of the tower to keep the molar ratio of salicylamide to phosgene at 1:2 and the synthesis temperature at 100°C. The reaction liquid overflows into the degassing tower through the U-shaped balance pipe at the bottom, and an online analyzer is installed on the U-shaped balance pipe to interlock the feed ratio of salicylamide and phosgene. The obtained salicylonitrile feed liquid is degassed with nitrogen in a degassing tower, keeping the molar ratio of nitrogen to phosgene at 1:0.5, maintaining the degassing temperature at 100°C, and obtaining the salicylonitrile xylene solution after the nitrogen...

Embodiment 2

[0023] The mass ratio of the salicylamide xylene solution to the salicylamide xylene solution is 1:8, and the temperature of the salicylamide xylene solution is kept at 90° C. through a solid automatic feeder and a solvent metering pump. The salicylamide xylene solution was injected from the top into the synthesis tower with packing, and phosgene was introduced from the bottom of the tower to keep the molar ratio of salicylamide to phosgene at 1:2.5 and the synthesis temperature at 90°C. The reaction liquid overflows into the degassing tower through the U-shaped balance pipe at the bottom, and an online analyzer is installed on the U-shaped balance pipe to interlock the feed ratio of salicylamide and phosgene. The obtained salicylonitrile feed liquid is degassed with nitrogen in a degassing tower, keeping the molar ratio of nitrogen and phosgene at 1:1, maintaining a degassing temperature of 90°C, and obtaining a salicylonitrile xylene solution after the nitrogen degassing is q...

Embodiment 3

[0025] The mass ratio of salicylamide xylene solution and salicylamide xylene solution is 1:6 through a solid automatic feeder and a solvent metering pump, and the temperature of the salicylamide xylene solution is kept at 50°C. The salicylamide xylene solution was injected from the top into the synthesis tower equipped with packing, and the phosgene was fed from the bottom of the tower to keep the molar ratio of salicylamide to phosgene at 1:3 and the synthesis temperature at 130°C. The reaction liquid overflows into the degassing tower through the U-shaped balance pipe at the bottom, and an online analyzer is installed on the U-shaped balance pipe to interlock the feed ratio of salicylamide and phosgene. The obtained salicyl nitrile feed liquid is degassed with nitrogen in a degassing tower, keeping the molar ratio of nitrogen and phosgene at 2:1, keeping the degassing temperature at 80°C, and obtaining the salicyl nitrile xylene solution after the nitrogen degassing is quali...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C253/20C07C255/53
CPCC07C253/20C07C255/53
Inventor 王卫华刘建军何小捷秦小虎雷宇钱茂公周天抒田庆海
Owner JIANGSU CHANGLONG AGROCHEM CO LTD
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