Carbamate intermediates over mesoporous carbon nitrides in CO2 mediated oxidation reaction

Abstract

Utilization of CO2 as an oxygen atom donor in the catalytic oxidation of organic compounds has gained much attention due to the potential capability of CO2 use as soft oxidant. Investigations were performed for the in-situ formation of carbamates over mesoporous carbon nitrides synthesized by different carbon and nitrogen sources urea-formaldehyde (UF-MCN), melamine-glyoxal (MG-MCN) and melamine (MS-MCN) under the CO2 stream in the infrared cell for the first time using diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). The capabilities of these carbamates were studied by in-situ DRIFTS as oxidation intermediates for “O” atom transfer to oxygen acceptor organic molecules like benzaldehyde. The formation of carbamate over mesoporous carbon nitrides was explored by Density functional theory (DFT) calculation as a first step towards new mechanistic insights for CO2 activation over metal-free catalyst involving “O” atom transfer. The catalytic potential of the mesoporous carbon nitrides for “O” atom transfer using CO2 were demonstrated by benzene to phenol and benzaldehyde to benzoic acid transformation reactions.