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

At 130degreesC 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 (similar to80%) of 1 are achievable only with supercritical carbon dioxide (scCO(2)) at 90 bar, which inhibits the forniation of N-methylated by-products. (C) 2002 Elsevier Science Ltd. All rights reserved.