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A kind of cleaning process for preparing diphenyl urea by urea method

A technology of diphenylurea and urea, applied in the field of preparation of diphenylurea, can solve problems such as unfavorable aniline and urea recycling, multiple by-products, etc., to improve yield and reduce the generation of by-product biuret , the effect of reducing the chance of contact

Inactive Publication Date: 2016-04-06
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the yield of diphenylurea obtained in the above two patents is relatively high, and no waste water is produced, relatively many by-products will be produced, which is not conducive to the recycling of unreacted materials aniline and urea, and the preparation process needs to be further optimized and boost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Under the protection of nitrogen, add aniline into the reactor, and when it is heated to a reaction temperature of 185°C, continuously feed nitrogen into the aniline, the flow rate of nitrogen is 2 times the volume of the reactor per hour, and then urea is continuously added to the reaction through a continuous feeding funnel The molar ratio of urea and aniline is 1:4, and the urea is added continuously for 30 minutes. The pressure of nitrogen is normal pressure before the urea is added. After the urea is added, the pressure is 0.8MPa, and the reaction temperature rises to 200°C , after continuing to react for 20min, stop the reaction, cool to room temperature, filter the reactant to obtain the filtrate and the product diphenylurea, sample the filtrate and the product diphenylurea, analyze with high performance liquid chromatography, the conversion of urea The rate is 100%, the productive rate of diphenylurea is 99.5%, and the productive rate of by-product biuret is 0.3%...

Embodiment 2

[0026] Under the protection of helium, add aniline into the reactor, when heated to the reaction temperature of 185°C, continuously feed helium into the aniline, the flow rate of helium is 3.5 times the reactor volume / hour, and then urea passes through the continuous feeding funnel Continuously add to the reactor, the molar ratio of urea and aniline is 1:6, the time of continuous adding urea is 10min, the pressure of helium is normal pressure before adding urea, after adding urea, the pressure is 0.6MPa, the reaction temperature Raise to 190°C, continue the reaction for 40 minutes, stop the reaction, cool to room temperature, filter the reactant to obtain the filtrate and the product diphenylurea, take samples of the filtrate and the product diphenylurea, and analyze them with high performance liquid chromatography , the conversion rate of urea was 99.0%, the yield of diphenylurea was 99.1%, and the yield of by-product biuret was 0.7%.

Embodiment 3

[0028] Under the protection of nitrogen, add aniline into the reactor, and when it is heated to a reaction temperature of 170°C, continuously feed nitrogen into the aniline, the flow rate of nitrogen is 5 times the volume of the reactor / hour, and then urea is continuously added to the reaction through a continuous feeding funnel In the container, add urea and aniline with a molar ratio of 1:9, and the time for continuously adding urea is 40 minutes. The pressure of nitrogen is normal pressure before adding urea, and after adding urea, the pressure is 0.2MPa, and the reaction temperature rises to 195°C , after continuing to react for 30min, stop the reaction, cool to room temperature, filter the reactant to obtain the filtrate and product diphenylurea, sample the filtrate and product diphenylurea, analyze with high performance liquid chromatography, the conversion of urea The rate is 100%, the productive rate of diphenylurea is 99.6%, and the productive rate of by-product biuret...

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Abstract

The invention discloses a clean process for preparing diphenyl urea by a urea method, and belongs to the technical field of diphenyl urea preparation. The clean process comprises the following steps: under the protection of an inert gas, adding an excessive amount of aniline into a reactor, heating to a first-stage reaction temperature, and keeping a certain inert gas flow; continuously adding urea into the reactor within a certain time through a continuous feeding hopper; heating to a second-stage reaction temperature and reacting to prepare the diphenyl urea. In the process, the aniline in the reactor is heated to a reaction temperature, and then the urea is added, so that the urea can be pyrolyzed quickly at a high temperature immediately to generate isocyanate, a byproduct of biuret is reduced, the yield of diphenyl urea is increased, meanwhile, the urea is continuously added into the reactor through the continuous feeding hopper, the production of the isocyanate can be controlled, the contact probability between isocyanate molecules and the aniline is increased, the contact probability between the isocyanate molecules and the urea is reduced, the byproduct of biuret can be reduced, and the yield of the diphenyl urea is increased.

Description

technical field [0001] The invention belongs to the technical field of preparation of diphenylurea, in particular to a cleaning process for preparing diphenylurea by urea method. Background technique [0002] Diphenylurea (DPU for short), also known as N,N′-diphenylurea, is an important organic chemical intermediate used in the preparation of sulfonamide drugs. At the same time, diphenylurea and its derivatives are also good plants Growth regulators, insecticides, herbicides. In addition, diphenyl urea can react with methanol or dimethyl carbonate to synthesize methyl phenylcarbamate, which is an important intermediate in the clean process of non-phosgene synthesis of diphenylmethane diisocyanate. [0003] The traditional industrial production method of diphenylurea is the urea method. This process uses water as the solvent and hydrochloric acid as the catalyst to produce diphenylurea by heating and reacting aniline and urea. The process uses water as a solvent, and a larg...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C273/18C07C275/28
Inventor 高俊杰张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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