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Method for preparing parachlorobenzyl isocyanic ester

A technology of chlorophenylisocyanate and p-chloroaniline, which is applied in the field of preparation of p-chlorophenylisocyanate, can solve problems such as safety accidents, phosgene leakage in solvents, etc., and achieve high production safety, low amount of three wastes, and low reaction efficiency. high rate effect

Active Publication Date: 2011-04-27
HUNAN CHEM RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Not only that, during the reaction heating process, it is easy to cause the leakage of phosgene in the solvent and cause a safety accident.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0007] Add 382.5 kilograms of toluene and 2.19 kilograms (30 moles) of catalyst N,N-dimethylformamide into a 1000-liter reactor with stirring, and stir at 4480 liters per hour after heating up to 105-110°C Speed ​​feeds phosgene (200 mol / hour), simultaneously with 51.0 kilograms / hour (200 mol / hour) dropwise the content 50% p-chloroaniline diluted with toluene, both add simultaneously and stop feeding after 5 hours, at this Stirring reaction was continued at temperature for 1 hour. Introduce dry nitrogen to remove acid gas, and recover toluene by distillation under reduced pressure. Finally, collect the distillate at 104-106°C at 5.3Kpa, which is p-chlorophenylisocyanate product, cool and solidify, melting point 29-31°C, content 99.5%, yield 92.3%.

Embodiment 2

[0009] Add 446.3 kilograms of toluene and 0.73 kilograms (10 moles) of catalyst N, N-dimethylformamide in a stirred 1000-liter reactor, stir and heat up to 105-110°C, then use 2800 liters per hour Speed ​​feeds phosgene (125 mol / hour), simultaneously with 15.94 kilograms / hour (62.5 mol / hour) dropwise the content 50% p-chloroaniline diluted with toluene, both add simultaneously and stop feeding after 8 hours, add The reaction was continued for 1 hour. Bubble dry nitrogen to remove acidic gas, recover toluene by distillation under reduced pressure, and finally collect the fraction at 103-105°C at 5.0Kpa, which is p-chlorophenyl isocyanate product, cool and solidify, melting point 29-31°C, content 99.6%, yield 95.8 %.

Embodiment 3

[0011] Add 446.3 kilograms of toluene and 0.31 kilograms (2.5 moles) of catalyst 4-dimethylaminopyridine into a stirred 1000-liter reactor. Enter phosgene (150 mol / hour), add dropwise the content 50% p-chloroaniline diluted with toluene with 31.9 kilograms / hour (125 mol / hour) simultaneously, both add simultaneously and stop feeding after 4 hours, add and continue reaction 1 hour. Bubble dry nitrogen to remove acidic gas, recover toluene by distillation under reduced pressure, and finally collect the distillate at 5.2Kpa at 104-106°C, which is p-chlorophenylisocyanate product, cool and solidify, melting point 29-31°C, content 99.0%, yield 94.6 %.

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Abstract

The invention discloses a preparation method for 4-chlorphenylisocyanate. The method is to use chloroanilines and gaseous phosgene as raw materials, and simultaneously add gaseous phosgene and chloroanilines to catalyst and an organic solvent to synthesize the 4-chlorphenylisocyanate is made by synthesis through one step, which is carried out at a temperature of between 70 and 160 DEG C for 5 to 9 hours, with a molar ratio of chloroanilines to the phosgene to the catalyst of 1.0:1.0-2.0:0.005-0.05, and the organic solvent with a mass 4 to 10 times that of the chloroanilines. The preparation method is characterized by simpler process route, higher reaction yield, less three wastes (waste gas, waste water and waste residues), easier purification, higher purity product, lower production cost, and higher safety of production without caking, etc., and has a greater practical value, and economic and social benefits, compared with the prior production art.

Description

technical field [0001] The invention relates to a preparation method of p-chlorophenyl isocyanate. Background technique [0002] p-Chlorophenyl isocyanate is an important intermediate of medicine, pesticide and polymer materials, such as trichlorosymmetric diphenylcarbamide (TCC) produced by it is a kind of high-efficiency broad-spectrum medical fungicide, diflubenzuron produced by it , Diflubenzuron No. 3 is a very important insecticide. The synthesis of p-chlorophenyl isocyanate can be made by reacting p-chloroaniline and carbonate, as Chinese patent CN1235874, and can also be made by reacting p-chloroaniline and phosgene, wherein phosgene can be solid phosgene, as Chinese patent CN101033203, Adopt p-chloroaniline and carbonate or solid phosgene to be the shortcoming that production cost is high in the production method of starting raw material, the prior art adopts p-chloroaniline and gaseous phosgene more as the production method of starting raw material, but process me...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C265/12C07C263/10
Inventor 刘卫东杜升华王晓光
Owner HUNAN CHEM RES INST