Selective Mono-N-alkylation of Aromatic Amines by Dialkyl Carbonate under Gas-Liquid Phase-Transfer Catalysis (GL-PTC) Conditions

Article abstract of DOI:10.1021/jo00383a024

The reaction between aromatic amines and dialkyl carbonates, carried out in gas phase under gas-liquid phase-transfer catalysis (GL-PTC) conditions, in a continuos-flow process, produces the mono-N-alkylation product and its carboxyalkyl derivative (selectivity > 99percent).The catalyst is a polyethylene glycol in the presence of a base (K2CO3).The reaction produces CO2 so it can be carried out indefinitively because the chemical nature of the catalytic bed, at steady conditions, does not change during the time.According to the mechanism discussed, this high selectivity might be due the following: (i) the reaction between the amine and dialkyl carbonate that produces only carboxymethylated compound (ArNHCOOR); (ii) the subsequent reaction of this intermediate with the dialkyl carbonate thet exclusively produces N-alkylated products (ArNRCOOR, from which ArNHR is selectively produced).