The synthesis of alkyl carbamates from primary aliphatic amines and dialkyl carbonates in supercritical carbon dioxide

At 130°C and in the presence of compressed CO2, primary aliphatic amines [RNH2, R=C10H21, C8H17, cHex, 1-(C10H7)CH2] react with organic carbonates (R′OCO2R; R′=Me, Et) to give alkyl carbamates (RNHCO2R′, 1). Although CO2 promotes the reaction also at a low pressure, good yields (∼80%) of 1 are achievable only with supercritical carbon dioxide (scCO2) at 90 bar, which inhibits the formation of N-methylated by-products.