CN112358419A - Synthesis process of 3, 4-dichlorophenyl isocyanate - Google Patents
Synthesis process of 3, 4-dichlorophenyl isocyanate Download PDFInfo
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- CN112358419A CN112358419A CN202011330789.9A CN202011330789A CN112358419A CN 112358419 A CN112358419 A CN 112358419A CN 202011330789 A CN202011330789 A CN 202011330789A CN 112358419 A CN112358419 A CN 112358419A
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- dichloroaniline
- dichlorophenyl isocyanate
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C263/00—Preparation of derivatives of isocyanic acid
- C07C263/04—Preparation of derivatives of isocyanic acid from or via carbamates or carbamoyl halides
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Abstract
The application discloses a synthesis process of 3, 4-dichlorophenyl isocyanate, which comprises the step of adding 3, 4-dichloroaniline and a solvent into a reaction kettle to obtain a 3, 4-dichloroaniline solution. Simultaneously adding solid phosgene into a reaction kettle, and heating to dissolve; the temperature of the reaction kettle reaches 60-100 ℃, the dripping speed is controlled by a DCS control system to begin to drip 3, 4-dichloroaniline solution in S1, so that 3, 4-dichloroaniline and solid phosgene generate 3, 4-dichloroaniline hydrochloride and 3, 4-dichlorobenzyl amino acyl chloride in a solvent medium; removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride obtained in the step S3 to obtain 3, 4-dichlorophenyl isocyanate, and after the dropwise addition is finished, carrying out reflux and heat preservation for 1-3 h; the acid-containing solvent is removed at normal pressure and recovered for use, and the concentrated solution is transferred to a rectifying still for rectification to obtain the product 3, 4-dichlorophenyl isocyanate. Green chemicals are used as production raw materials, and potential safety hazards caused by phosgene leakage are reduced. The general chemical solid phosgene is adopted to replace virulent phosgene to serve as an acylation reagent, and a green degradable ester solvent is adopted as a reaction medium.
Description
Technical Field
The invention belongs to the technical field of preparation of 3, 4-dichlorophenyl isocyanate, and particularly relates to a synthesis process of 3, 4-dichlorophenyl isocyanate.
Background
The 3, 4-dichlorophenyl isocyanate is an important intermediate of medicines, pesticides and high molecular materials, is mainly used for synthesizing pesticides such as urea herbicides and pesticides, synthesizing certain medical intermediates, reacting the intermediates with alcohol and amine to prepare derivatives, and can also be used for identifying compounds. The synthesis of 3, 4-dichlorophenyl isocyanate can be carried out by reacting 3, 4-dichloroaniline with phosgene in inert solvent toluene at low temperature and high temperature in two stages, such as Chinese patent CN 107235860A. Chinese patents CN101781236A and CN102617407A both propose target compounds obtained by passing light through 3, 4-dichloroaniline at low temperature and then slowly passing light through the dichloroaniline. These methods all use phosgene as acylation reagent, and adopt low-temperature and high-temperature two-stage method with long period. Meanwhile, in order to improve the reaction effect, the excessive phosgene is required to be discharged to a tail gas system, so that the phosgene is wasted, and potential safety hazards caused by phosgene leakage exist.
Disclosure of Invention
The invention aims to provide a synthesis process of 3, 4-dichlorophenyl isocyanate, which takes green chemicals as production raw materials and reduces the potential safety hazard caused by phosgene leakage. The general chemical solid phosgene is adopted to replace virulent phosgene to serve as an acylation reagent, and a green degradable ester solvent is adopted as a reaction medium.
In order to solve the technical problems, the invention adopts the following technical scheme:
a synthesis process of 3, 4-dichlorophenyl isocyanate comprises the following steps:
s1, adding 3, 4-dichloroaniline and a solvent into the reaction kettle to obtain a 3, 4-dichloroaniline solution.
S2, adding solid phosgene into the reaction kettle, and heating to dissolve;
s3, controlling the dropping speed by a DCS control system to start dropping a 3, 4-dichloroaniline solution in S1 when the temperature of the reaction kettle reaches 60-100 ℃, so that 3, 4-dichloroaniline hydrochloride and 3, 4-dichlorobenzyl amino acyl chloride are generated by 3, 4-dichloroaniline and solid phosgene in a solvent medium;
s4, removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride obtained in the step S3 to obtain 3, 4-dichlorophenyl isocyanate, and after dropwise addition, refluxing and preserving heat for 1-3 hours;
and S5, removing the acid-containing solvent at normal pressure, recovering and recycling, transferring the concentrated solution to a rectifying still, and rectifying to obtain the product 3, 4-dichlorophenyl isocyanate.
Preferably, in S1, the mass ratio of the 3, 4-dichloroaniline to the solvent is 1: 3.5-6.5.
Preferably, the mass ratio of the 3, 4-dichloroaniline to the solvent in S1 is 1: 5.0.
Preferably, in S2, the mass ratio of the solid phosgene to the solvent is 1: 2.0 to 4.0.
Preferably, in S2, the mass ratio of the solid phosgene to the solvent is 1: 3.0.
preferably, the molar ratio of the 3, 4-dichloroaniline to the solid phosgene in S2 is 1: 0.34-0.40.
Preferably, the molar ratio of 3, 4-dichloroaniline to phosgene solid in S2 is 1: 0.37.
Preferably, the solvent is ethyl acetate, butyl acetate or sec-butyl acetate.
Preferably, the solid phosgene is bis (trichloromethyl) carbonate.
Preferably, in the S5, the yield of the product 3, 4-dichlorophenyl isocyanate is 94%, and the product content is more than or equal to 99.0%.
The invention has the following beneficial effects:
1. the solid phosgene is bis (trichloromethyl) carbonate which is used as a substitute of phosgene and diphosgene, and has the characteristics of safety, economy, convenient use, no pollution, accurate reaction measurement and the like.
2. The green and environment-friendly esters are used as solvents, so that the investment of toxic and harmful substances is reduced from the source. Meanwhile, the temperature is easy to control, the reaction efficiency is high, and the yield and the quality of the product are ensured at a higher level.
3. The one-step method is adopted for synthesis, so that the synthesis period is shortened, the efficiency is improved, and the energy consumption is saved, because the reaction efficiency of 3, 4-dichloroaniline and solid phosgene is high at 60-100 ℃, the product mainly comprises an unstable intermediate product 3, 4-dichlorobenzyl amino acyl chloride, and a small amount of 3, 4-dichloroaniline hydrochloride can efficiently react with the solid phosgene at the temperature to generate the 3, 4-dichlorobenzyl amino acyl chloride, so that the reaction period is shortened, and the reaction efficiency is improved.
4. A DCS automatic control system is adopted in the process, so that the metering, temperature control and dropping speed of materials are more accurate, and the reaction conditions are more stable.
Detailed Description
In order to facilitate a better understanding of the invention, the following examples are given to illustrate, but not to limit the scope of the invention.
Example 1
Firstly, 3, 4-dichloroaniline and a solvent are uniformly mixed in a mixing kettle according to the mass ratio of 1:5 to prepare a 3, 4-dichloroaniline solution. Simultaneously adding bis (trichloromethyl) carbonate and a solvent in a mass ratio of 1: and 3, heating to dissolve. The molar ratio of 3, 4-dichloroaniline to bis (trichloromethyl) carbonate was 1: 0.37. And when the temperature of the reaction kettle reaches 80 ℃, controlling the dropping speed by a DCS (distributed control system) control system to begin to drop 3, 4-dichloroaniline solution, so that 3, 4-dichloroaniline and solid phosgene generate a small amount of 3, 4-dichloroaniline hydrochloride and unstable intermediate product 3, 4-dichlorobenzyl amino acyl chloride in a solvent medium, and removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride to obtain the 3, 4-dichlorophenyl isocyanate. The dropwise adding reaction time is 1.3h, and after the dropwise adding is finished, the reflux and heat preservation are carried out for 2 h. The acid-containing solvent is removed under normal pressure and recovered for reuse, and the concentrated solution is transferred to a rectifying still. Rectifying to obtain the product 3, 4-dichlorophenyl isocyanate with yield of 94% and product content not less than 99.0%, and burning the residue.
Example 2
Firstly, 3, 4-dichloroaniline and a solvent are uniformly mixed in a mixing kettle according to the mass ratio of 1:3.5 to prepare a 3, 4-dichloroaniline solution. Simultaneously adding bis (trichloromethyl) carbonate and a solvent in a mass ratio of 1: 4.0, heating to dissolve. The molar ratio of 3, 4-dichloroaniline to bis (trichloromethyl) carbonate was 1: 0.34. And (3) controlling the dropping speed by a DCS (distributed control system) control system to start to drop 3, 4-dichloroaniline solution to enable 3, 4-dichloroaniline and solid phosgene to generate a small amount of 3, 4-dichloroaniline hydrochloride and unstable intermediate product 3, 4-dichlorobenzyl amino acyl chloride in a solvent medium, and removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride to obtain the 3, 4-dichlorophenyl isocyanate when the temperature of the reaction kettle reaches 100 ℃. The dropwise adding reaction time is 0.5h, and after the dropwise adding is finished, the reflux and heat preservation are carried out for 3 h. The acid-containing solvent is removed under normal pressure and recovered for reuse, and the concentrated solution is transferred to a rectifying still. Rectifying to obtain the product 3, 4-dichlorophenyl isocyanate with yield of 94% and product content not less than 99.0%, and burning the residue.
Example 3
Firstly, 3, 4-dichloroaniline and a solvent are uniformly mixed in a mixing kettle according to the mass ratio of 1:6.5 to prepare a 3, 4-dichloroaniline solution. Simultaneously adding bis (trichloromethyl) carbonate and a solvent in a mass ratio of 1: and 2.0, heating to dissolve. The molar ratio of 3, 4-dichloroaniline to bis (trichloromethyl) carbonate was 1: 0.40. And (3) controlling the dropping speed by a DCS (distributed control system) control system to start dropping a 3, 4-dichloroaniline solution so that 3, 4-dichloroaniline and solid phosgene generate a small amount of 3, 4-dichloroaniline hydrochloride and an unstable intermediate product, namely 3, 4-dichlorobenzyl amino acyl chloride in a solvent medium, and removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride to obtain the 3, 4-dichlorophenyl isocyanate. The dropwise adding reaction time is 2.0h, and after the dropwise adding is finished, the reflux and heat preservation are carried out for 1 h. The acid-containing solvent is removed under normal pressure and recovered for reuse, and the concentrated solution is transferred to a rectifying still. Rectifying to obtain the product 3, 4-dichlorophenyl isocyanate with yield of 94% and product content of not less than 99.0%, and burning the residue
It can be understood that the DCS is a decentralized control system, and is a new generation of instrument control system based on a microprocessor and adopting a design principle of decentralized control function, centralized display operation, and consideration of both autonomous and comprehensive coordination.
Example 4
11.88g of bis (trichloromethyl) carbonate and 150ml of toluene were added to a 500ml four-necked flask equipped with a-20 ℃ refrigerated ethanol reflux apparatus and dissolved by stirring. And (3) dropwise adding 150ml of toluene solution dissolved with 100mmol of arylamine into the reaction solution at 0-10 ℃ within 45min, and then heating and refluxing for 2-3 h until the reaction solution becomes clear. Then, dry nitrogen gas is introduced into the reaction solution under the reflux state, and the residual hydrogen chloride gas and a very small amount of phosgene are driven to a recovery bottle and a tail gas absorption bottle until the pH value of the tail gas is about 7. And cooling the reaction liquid to room temperature, slowly introducing 6.75g of dimethylamine gas while stirring, stopping the reaction after about 30min, filtering, and drying in vacuum to obtain a powdery crystalline product.
Based on the above embodiment, bis (trichloromethyl) carbonate is a solid at normal temperature, can be accurately weighed, is convenient to feed, and can be completely reacted generally only by a small amount of bis (trichloromethyl) carbonate.
The above description should not be taken as limiting the invention to the embodiments, but rather, as will be apparent to those skilled in the art to which the invention pertains, numerous simplifications or substitutions may be made without departing from the spirit of the invention, which shall be deemed to fall within the scope of the invention as defined by the claims appended hereto.
Claims (10)
1. A synthesis process of 3, 4-dichlorophenyl isocyanate is characterized by comprising the following steps:
s1, adding 3, 4-dichloroaniline and a solvent into a reaction kettle to obtain a 3, 4-dichloroaniline solution;
s2, adding solid phosgene into the reaction kettle, and heating to dissolve;
s3, controlling the dropping speed by a DCS control system to start dropping a 3, 4-dichloroaniline solution in S1 when the temperature of the reaction kettle reaches 60-100 ℃, so that 3, 4-dichloroaniline hydrochloride and 3, 4-dichlorobenzyl amino acyl chloride are generated by 3, 4-dichloroaniline and solid phosgene in a solvent medium;
s4, removing hydrogen chloride from the 3, 4-dichlorobenzyl amino acyl chloride obtained in the step S3 to obtain 3, 4-dichlorophenyl isocyanate, dropwise adding for reaction for 0.5-2.0h, and after dropwise adding, refluxing and preserving heat for 1-3 h;
and S5, removing the acid-containing solvent at normal pressure, recovering and recycling, transferring the concentrated solution to a rectifying still, and rectifying to obtain the product 3, 4-dichlorophenyl isocyanate.
2. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 1, wherein the mass ratio of 3, 4-dichloroaniline to solvent in S1 is 1: 3.5-6.5.
3. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 2, wherein the mass ratio of 3, 4-dichloroaniline to solvent in S1 is 1: 5.0.
4. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 1, wherein in S2, the mass ratio of the solid phosgene to the solvent is 1: 2.0 to 4.0.
5. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 4, wherein in S2, the mass ratio of the solid phosgene to the solvent is 1: 3.0.
6. the process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 1, wherein the molar ratio of 3, 4-dichloroaniline to phosgene solid in S2 is 1: 0.34-0.40.
7. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 6, wherein the molar ratio of 3, 4-dichloroaniline to phosgene solid in S2 is 1: 0.37.
8. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 1, wherein said solvent is ethyl acetate, butyl acetate or sec-butyl acetate.
9. The process of claim 1 for the synthesis of 3, 4-dichlorophenyl isocyanate, wherein said phosgene is bis (trichloromethyl) carbonate.
10. The process for synthesizing 3, 4-dichlorophenyl isocyanate according to claim 1, wherein the yield of 3, 4-dichlorophenyl isocyanate in S5 is 94%, and the content of the product is not less than 99.0%.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114210289A (en) * | 2021-12-31 | 2022-03-22 | 夏剑锋 | Production process of p-phenylene diisocyanate |
| CN114315574A (en) * | 2021-12-31 | 2022-04-12 | 河南豫辰药业股份有限公司 | Preparation method of carbasalate calcium |
| CN114380716A (en) * | 2022-01-27 | 2022-04-22 | 浙江丽水有邦新材料有限公司 | Production method and production system of p-chlorophenyl isocyanate |
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| CN101274904A (en) * | 2008-04-28 | 2008-10-01 | 江苏安邦电化有限公司 | Preparation for 3, 4-dichloro phenyl isocyanate |
| CN107827824A (en) * | 2017-12-06 | 2018-03-23 | 江西禾益化工股份有限公司 | A kind of method for synthesizing iprodione |
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2020
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| GB789265A (en) * | 1956-01-24 | 1958-01-15 | Du Pont | Improvements in or relating to isocyanates |
| CN1478769A (en) * | 2003-05-08 | 2004-03-03 | 蔡戈冬 | Chemical synthesis method of 3,4-dichlorobenzene isocyanate |
| CN101274904A (en) * | 2008-04-28 | 2008-10-01 | 江苏安邦电化有限公司 | Preparation for 3, 4-dichloro phenyl isocyanate |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114210289A (en) * | 2021-12-31 | 2022-03-22 | 夏剑锋 | Production process of p-phenylene diisocyanate |
| CN114315574A (en) * | 2021-12-31 | 2022-04-12 | 河南豫辰药业股份有限公司 | Preparation method of carbasalate calcium |
| CN114380716A (en) * | 2022-01-27 | 2022-04-22 | 浙江丽水有邦新材料有限公司 | Production method and production system of p-chlorophenyl isocyanate |
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