Method for recycling aniline in phenyl carbamate preparation process by urea coupling method

A phenylcarbamate, recycling technology, applied in the preparation of carbamic acid derivatives, preparation of organic compounds, chemical instruments and methods, etc., can solve the problems of difficult recycling and separation of aniline, and achieve simple process, High catalytic activity and selectivity, good reproducibility

Inactive Publication Date: 2013-05-22
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

In the reaction process, under the action of the bifunctional catalyst, the crude product of diphenylurea does not need to be washed, and diphenylurea and the residual aniline therein react with dimethyl carb

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The crude product N,N'-diphenylurea containing a small amount of aniline without washing with solvents such as methanol (the crude product contains 0.2 moles of N,N'-diphenylurea and 0.01 moles of aniline), dimethyl carbonate 2 Mole, 0.85 grams of bifunctional catalyst (including 0.425 grams of lead monoxide and 0.425 grams of zinc oxide), was added to the autoclave, then the autoclave was sealed, and the air in the autoclave was replaced with nitrogen, and then 2 MPa of nitrogen was added, and the high pressure The kettle was heated to 170°C under magnetic stirring, and the reaction time was 4 hours. After the reaction was cooled to room temperature, the reaction solution was sampled and analyzed by high-performance liquid chromatography. The conversion rate of N,N'-diphenylurea was 99%. The conversion rate of aniline was 100%, and the yield of methyl phenylcarbamate was 98%.

Embodiment 2

[0029] The crude product N,N'-diphenylurea containing a small amount of aniline without washing with solvents such as methanol (the crude product contains 0.2 moles of N,N'-diphenylurea and 0.004 moles of aniline), dimethyl carbonate 1 Mole, 0.47 grams of bifunctional catalyst (wherein 0.235 grams of lead monoxide, 0.235 grams of zinc oxide,), join in the autoclave, then airtight autoclave, with CO 2 After replacing the air in the kettle, add 3MPa nitrogen, the autoclave is heated to 170°C under magnetic stirring, and the reaction time is 4 hours. After the reaction is cooled to room temperature, the reaction solution is sampled and analyzed by high performance liquid chromatography. , The conversion rate of N'-diphenylurea was 96%, the conversion rate of aniline was 99%, and the yield of methyl phenylcarbamate was 95%.

Embodiment 3

[0031] The crude product N,N'-diphenylurea containing a small amount of aniline without washing with solvents such as methanol (the crude product contains 0.2 moles of N,N'-diphenylurea and 0.02 moles of aniline), dimethyl carbonate 4 Mole, 2.12 grams of bifunctional catalyst (including 1.06 grams of lead monoxide and 1.06 grams of dibutyltin oxide), was added to the autoclave, then the autoclave was sealed, and the air in the autoclave was replaced with nitrogen, and then 0.5MPa was added The nitrogen gas in the autoclave was raised to 170°C under magnetic stirring, and the reaction time was 1 hour. After the reaction was cooled to room temperature, the reaction liquid was sampled and analyzed by high performance liquid chromatography. The conversion rate of N,N'-diphenylurea 99%, the conversion rate of aniline is 100%, and the yield of methyl phenylcarbamate is 99%.

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Abstract

The invention discloses a method for recycling aniline in a phenyl carbamate preparation process by a urea coupling method, belonging to the technical field of non-phosgene synthesis of phenyl carbamate. Under the catalytic action of a bifunctional catalyst, a crude product N,N'-diphenylurea containing a small amount of aniline, which is obtained by an improved urea method and is not washed by methanol or any other solvent, is used as a raw material to directly react with carbonate to prepare the phenyl carbamate, i.e. the N,N'-diphenylure and residual aniline in the N,N'-diphenylure simultaneously react with dimethyl carbonate to efficiently synthesize the phenyl carbamate. The invention has the advantage of mild reaction conditions, uses the high-activity bifunctional catalyst, does not need to separate the small amount of aniline in the N,N'-diphenylure, and uses the aniline as the reaction raw material, thereby implementing aniline recycling at low cost, and solving the problem of difficulty in separating and recycling aniline in the transfer process.

Description

technical field [0001] The invention belongs to the technical field of non-phosgene synthesis of aniline carbamate, in particular to a method for recycling aniline in the process of preparing aniline carbamate by a urea coupling method. Background technique [0002] Isocyanate is an important class of organic synthesis intermediates, widely used in polyurethane, coatings, dyes and pesticides and other fields. In the traditional isocyanate synthesis industry, most products are synthesized by the phosgene method. With the increasing environmental protection requirements, the development of non-phosgene synthesis methods has become a very important topic in the chemical industry. Phenyl carbamate is a very key intermediate in the process of non-phosgene synthesis of isocyanate, and its non-phosgene synthesis process has become a research hotspot. [0003] The non-phosgene synthesis of phenylcarbamate mainly includes oxidative carbonylation of aniline, reductive carbonylation o...

Claims

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Application Information

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IPC IPC(8): C07C269/00C07C269/04C07C271/28
Inventor 高俊杰张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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