Novel Synthesis of Carbamate Ester from Carbon Dioxide, Amines, and Alkyl Halides

Abstract

A novel synthesis of carbamate ester using carbon dioxide as a direct material is reported in this article. The direct reaction of carbon dioxide, aliphatic amines, and alkyl halides was found to give the corresponding alkyl carbamate esters in good yields. Reactions using secondary alkyl bromides gave carbamate esters in higher yields than those using primary or tertiary alkyl bromides. The carbamate ester yields increased with the addition of N,N-dimethylformamide to the reaction system of carbon dioxide, amines and, alkyl halides. This reaction is considered to proceed by an SN2 displacement reaction of the alkyl halide by the carbamate anion formed from the reaction of carbon dioxide and the amine.