Dimethylcarbonate for the Catalytic Upgrading of Amines and Bio-Based Derivatives

An archetype of a green and sustainable strategy for the catalytic upgrading of both anilines and bio-based derivatives including glycerol acetals, p-coumaryl-like alcohols, and lactones can be devised by the use of dimethyl carbonate (DMC). In the presence of different heterogeneous catalysts such as alkaline carbonates and alkali metal-exchanged faujasites, DMC allows quantitative mono-N-methylation and O-methylation processes with excellent selectivity up to 99% and no by-products except for methanol (recyclable to the synthesis of DMC) and CO2. Also, selective transesterifications of DMC with glycerol acetals and lactones can be achieved under thermal or catalytic conditions. The mechanism of such reactions has been formulated based on the steric requisites and the amphoteric nature of faujasites, the combined effect of the temperature and base catalysts, and the ambident electrophilic reactivity of DMC. Overall, methylations and methoxycarbonylations mediated by DMC are not only more selective but far safer than conventional procedures involving noxious phosgene and methyl halides or dimethyl sulfate.