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Method for preparing carbamate

A carbamate and amino technology, applied in the field of carbamate preparation, can solve the problems of carbamate storage or use adverse effects, harsh reaction operating conditions, water decomposition, etc., to achieve good stability and low price , good chemical properties

Inactive Publication Date: 2011-07-27
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] As can be seen, in the above-mentioned existing dimethyl carbonate aminolysis method for preparing carbamate routes, the catalysts involved are mainly divided into two categories, namely: salts of transition metals or IIIA-VA group metals and alkali metals or Alcoholates of alkaline earth metals, these catalysts all have certain deficiencies
After the first type of catalyst finishes the reaction and is separated from the reaction system, a certain amount of metal ions will remain in the product carbamate, and these metal ions are the active components of commonly used catalysts, so they are easy to react with carbamate. Storage or use of esters may have adverse effects
The second type of catalyst is expensive, decomposes with water, and has harsh reaction operating conditions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Embodiment 1 blank experiment

[0013] In a 250 ml three-necked flask, add 11.6 grams of hexamethylenediamine and 70 ml of dimethyl carbonate in sequence, and heat up to 80°C under stirring. After reacting for 8 hours, extract excess dimethyl carbonate and methanol under reduced pressure to obtain a white powder . Then 200ml of distilled water was added, heated to 100°C, and then cooled to room temperature, and white crystals of methyl hexamethylenedicarbamate were precipitated. The reaction conversion rate was 10%, the selectivity was 90%, and the yield was 9%.

Embodiment 2

[0014] The contrast of embodiment 2 sodium acetate catalyst and blank experiment

[0015] In a 250 ml three-necked flask, add 11.6 grams of hexamethylenediamine, 70 ml of dimethyl carbonate, and 0.8 grams of sodium acetate successively, and heat up to 80° C. under stirring. After reacting for 8 hours, extract excess dimethyl carbonate and methanol to give a white powder. Then 200ml of distilled water was added, heated to 100°C, and then cooled to room temperature, and white crystals of methyl hexamethylenedicarbamate were precipitated, with a reaction conversion rate of 96%, a selectivity of 90%, and a yield of 86.4%.

Embodiment 3

[0016] Embodiment 3 sodium acetate catalyst, methanol solvent

[0017] In a 250 ml three-necked flask, add 11.6 grams of hexamethylenediamine, 70 ml of dimethyl carbonate, 20 ml of methanol, and 1.6 grams of sodium acetate in sequence, and raise the temperature to 70°C under stirring. After reacting for 6 hours, the excess dicarbonate is extracted under reduced pressure. methyl ester and methanol to give a white powder. Then add 200ml of distilled water, heat to 100°C, and then cool to room temperature, and white crystals of methyl hexamethylenedicarbamate are precipitated, with a purity of >99% and a yield of >98%.

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Abstract

The invention relates to a method for preparing carbamate. The method for preparing the carbamate comprises the following processes of: dissolving carbonic ester, amine and acetate catalyst into a proper solvent so that the molar ratio of the carbonic diester to the amine is 2 to 20 times stoichiometric ratio and the molar ratio of the catalyst to the amine is 1:5-1:100; and then reacting for 0.5 to 16 hours at the temperature of between 30 and 160 DEG C, and performing separation and purification to obtain the required carbamate. The method has the main advantages that: the catalyst has stable chemical performance and low price; and the product separation and purification processes are simple.

Description

technical field [0001] The present invention relates to a method for preparing carbamate. Background technique [0002] Carbamate compounds have a wide range of uses and can be used as intermediates in pesticides, medicines, synthetic resin modification, and organic synthesis. As an intermediate in organic synthesis, it can be used to synthesize isocyanate, non-toxic polyurethane, dipolycyanamide derivatives, dialkyl carbonate and polyvinylamine, etc. Carbamate can be combined with unsaturated hydrocarbons, aldehydes, ketones, polyols and aromatic rings and other reactions to generate derivatives for various purposes, and can also be used to synthesize heterocyclic compounds such as pyrrole, triadimefon and quinimizolone, and has a good application prospect. [0003] The traditional synthesis method mainly uses highly toxic phosgene as raw material, and obtains carbamate through alcoholysis and ammonolysis. In recent years, with the development of society, countries pay mo...

Claims

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Application Information

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IPC IPC(8): C07C269/04C07C271/20B01J31/04
Inventor 晁自胜孙大雷谢顺吉
Owner HUNAN UNIV
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