METHOD FOR DIALKYLCARBONATE PREPARATION Russian patent published in 2009 - IPC C07C68/08 C07C69/96 

FIELD: chemistry.

SUBSTANCE: invention refers to the improved method of dialkylcarbonate preparation due to interreaction of an alcohol, e.g. C₁-C₃ alcohols, with carbamide including removal in the prereactor of the water and ammonium carbamates admixture in starting materials. The water reacts with initial carbamide generating ammonium carbamate which is destructed together with present in starting materials ammonium carbamates to ammonia and carbon dioxide. Besides some amount of carbamide reacts with alcohol in the first reactor generating alkylcarbamate which is dialkylcarbonate precursor. Dialkylcarbonates are obtained in the second reaction zone. Undesirable side-products - alkyl-N-alkylcarbamates are continuously distilled off from second reaction zone together with ammonia, alcohol and dialkylcarbonates in steady mode of reactor operation. Alkyl-N-alkylcarbamate can be transformed to heterocyclic compounds in the third reaction zone in order to remove the solid material from the system. Admixtures removal from raw material flow is the main object of prereactor use. The additional improvement is made due to partial transformation of carbamide to alkylcarbamate proceeding in the prereactor which leads to increase of dialkylcarbonate formation rate in the primary reactor and to the decrease of alcohol recycle to the primary reactor.

EFFECT: increased dialkylcarbonate concentration in the upper flow from primary reactor reduces the dialkylcarbonate separation cost.

23 cl, 5 dwg, 3 tbl, 5 ex