Method for synthesis of carbamate under mild conditions

Abstract

The invention discloses a method for synthesis of carbamate under mild conditions. Urea and methanol are used as raw materials, and in the presence of a solid oxide catalyst, a sweeping gas is continuously introduced during the reaction process, so that methyl carbamate is synthesized under mild conditions. Under the optimized reaction conditions, the conversion rate of urea is more than 90%, the selectivity of methyl carbamate is more than 99.9%, and the decomposition rate of urea is less than 1%. The method has advantages of simple preparation method of the catalyst, mild reaction conditions, high selectivity of methyl carbamate, less urea decomposition, no deterioration during the reaction process, easy separation of the catalyst, good catalyst repeatability and the like.

Description

technical field [0001] The invention relates to a method for synthesizing carbamate by reacting urea and methanol under mild conditions in the presence of a catalyst. Background technique [0002] Methyl carbamate (MC) is a widely used chemical, which can be used as pesticide, medicine, synthetic resin modifier and organic synthesis intermediate, etc. When used as an intermediate in organic synthesis, it can react with polyamine compounds to generate polycarbamate, and then synthesize isocyanate through non-phosgene thermal cracking method; MC and polyol undergo transesterification to obtain polyol carbamate Then further cross-linking reaction with aldehydes to generate non-toxic polyurethane without residual toxic isocyanate group polyurethane structure, which is widely used as coatings, adhesives, etc.; MC has moderate volatility, odorless, and toxicity lower advantages. MC can also be used to synthesize derivatives of triazolone, heterocyclic pyrrole, quinazolinone and ...

AI Technical Summary

Problems solved by technology

Generally, when the reaction temperature exceeds 160°C, by-products are easy to form, which makes it difficult for the subsequent separation and purification and the improvement of the quality of the target product MC

At the same time, the higher temperature will lead to a rapid increase in the reaction pressure, resulting in difficulties in the discharge of ammonia gas, hindering the conversion of raw material urea, increasing the cost of the reactor and the risk of safe production