Method for continuously preparing 3,4-dichlorophenyl isocyanate

A technology of dichlorophenylisocyanate and dichloroaniline, which is applied in the field of continuous production and preparation of 3,4-dichlorophenylisocyanate, can solve the problems of waste of phosgene, easy bumping of materials, long cycle, etc., and achieve process performance Less energy consumption and higher production efficiency

Active Publication Date: 2015-02-18
湖南海利常德农药化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These methods produce 1 The cycle is long and the material is prone to bumping during the heating process, and phosgene is easy to leak out
Moreover, these are all single-pot batch-type production methods, because the gas phosgene needs to be excessively contacted with 3,4-dichloroaniline to react well, so the excessive phosgene needs to be discharged to the absorption device in time, which not only causes Reduce the waste of phosgene, and make the phosgene easy to leak, causing safety hazards

Method used

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  • Method for continuously preparing 3,4-dichlorophenyl isocyanate
  • Method for continuously preparing 3,4-dichlorophenyl isocyanate
  • Method for continuously preparing 3,4-dichlorophenyl isocyanate

Examples

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Effect test

Embodiment 1

[0019] Add 900Kg 3,4-dichloroaniline (content 99%) and 1500Kg dichloroethane into a 3000-liter mixing tank, stir and dissolve evenly, and add 250 liters of them respectively to the 1000-liter reactors A, B and C connected in series Dichloroethane, after stirring and raising the temperature to about 60°C, simultaneously feed phosgene at a rate of 5973 liters (240 moles) / hour, 5475 liters (220 moles) / hour, and 4978 liters (200 moles) / hour (content 90%), dropwise add the mixed 3,4-dichloroaniline dichloroethane solution in reactor A, B, C at the speed of 87.2Kg (200 mol) / hour simultaneously, collect each one continuously after one hour The reaction liquid in the reaction kettle is sent to the exhaust tank, and the nitrogen gas is turned on to drive away the mixed gas containing a small amount of phosgene and a large amount of hydrochloric acid gas in the reaction liquid. The mixed gas enters the low-temperature cooling device and then enters the tail gas absorption system. The pr...

Embodiment 2

[0021] Add 900Kg 3,4-dichloroaniline (content 99%) and 900Kg dichloroethane into a 3000-liter mixing tank, stir and dissolve evenly, and add 250 liters of them respectively in the 1000-liter reactors A, B and C connected in series After dichloroethane is stirred and heated to about 60°C, phosgene is introduced at the speed of 5973 liters / hour (240 moles) / hour, 5475 liters (220 moles) / hour and 4978 liters (200 moles) / hour respectively. (content 90%), at the same time, drop the mixed 3,4-dichloroaniline dichloroethane solution into the reactors A, B, and C at a speed of 65.4Kg (200 mol) / hour. After one hour, continuously collect the reaction liquid from each reactor to the flushing tank, turn on the nitrogen gas, and drive away the mixed gas containing a small amount of phosgene and a large amount of hydrochloric acid gas in the reaction liquid. The mixed gas enters the low-temperature cooling device and then enters the tail gas absorption system. The reaction liquid after being...

Embodiment 3

[0023] Add 900Kg 3,4-dichloroaniline (content 99%), 600Kg dichloroethane in the 3000-liter mixing tank, stir and dissolve evenly, and add 330 kg respectively in the 1000-liter reactors A, B and C connected in series After liters of dichloroethane, stir and heat up to about 60°C, at the same time pass light at the speed of 5973 liters (240 moles) / hour, 5475 liters (220 moles) / hour, 4978 liters (200 moles) / hour gas (content 90%), and at the same time drop the mixed 3,4-dichloroaniline dichloroethane solution into the reactors A, B, and C at a speed of 54.5Kg (200 mol) / hour. After one hour, continuously collect the reaction liquid from each reactor to the flushing tank, turn on the nitrogen gas, and drive away the mixed gas containing a small amount of phosgene and a large amount of hydrochloric acid gas in the reaction liquid. The mixed gas enters the low-temperature cooling device and then enters the tail gas absorption system. The reaction solution after being purged with nitr...

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Abstract

The invention discloses a method for preparing 3,4-dichlorophenyl isocyanate through continuous feeding reaction by using 3,4-dichloroaniline and phosgene as raw materials and using dichloroethane, methylbenzene, dimethylbenzene, chlorobenzene or o-dichlorobenzene as a reaction solvent. According to the method, hydrochloric acid gas generated in reaction can continuously generate 3,4-dichloroaniline hydrochloride together with 3,4-dichloroaniline, 3,4-dichloroaniline hydrochloride continues to react with phosgene at high temperature to remove hydrochloric acid and generate isocyanate, tail gas containing phosgene and the hydrochloric acid gas generated after reaction of each stage is fully utilized in reaction of next stage, and phosgene is utilized to the maximum extent. The method is safe and environment-friendly; in addition, the energy consumption of the whole process is low and the production efficiency is greatly improved.

Description

technical field [0001] The invention relates to a method for continuous production and preparation of 3,4-dichlorophenyl isocyanate. Background technique [0002] 3,4-dichlorophenyl isocyanate is a pesticide intermediate, mainly used in new high-efficiency herbicides (such as Diuron, Liguron, Triburon, Mizam), fungicide Kang Jiexin and some pharmaceutical intermediates Synthesis of body etc. The structural formula is: [0003] [0004] Its synthesis method includes the reaction of 3,4-dichloroaniline with diphosgene and solid phosgene, such as Chinese patent CN1478769A. It can also be prepared by thermal decomposition of 3,4-dichlorocarbamate, such as Chinese patent CN102399170A. These methods all have the disadvantage of high production cost. The current production process mostly uses 3,4-dichloroaniline to react with gas phosgene, such as Chinese patent CN101274904A adopts low-temperature, high-temperature two-step phosgenation process, and Chinese patents CN1017812...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/12C07C263/10
Inventor 杜升华刘卫东刘源兰世林王艳丽黄超群
Owner 湖南海利常德农药化工有限公司
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