The Dissociation Chemistry of Ionized Methyl Carbamate and its Isomers Revisited: Theory and Experiment in Concert

Early combined computational and experimental studies by J.K. Terlouw and colleagues propose that low-energy methyl carbamate ions, NH2COOCH3•+ (MC-1), rearrange into distonic ions NH2C(OH)OCH2•+ and hydrogen-bridged radical cations [NH2C=O–H–OCH2]•+ (MC-5) en route to the observed losses of HCO• and CO. In this study, we report on the generation of ionsMC-5 by decarbonylation of ionized methyl oxamate NH2COCOOCH3•+. Theory and experiment agree that ionMC-5 is a key intermediate in the dissociation of low-energy ionsMC-1. The subsequent HCO• loss, however, may not proceed via the route proposed by Terlouw et al., but rather by an entirely different mechanism involving proton–transport catalysis (PTC) in ionMC-5. This view is further supported by the dissociation behaviour of theMC-5 isotopologue [ND2C=O–D–OCH2]•+, which is conveniently generated from the d3-labelled glycolamide ion DOCH2C(=O)ND2•+

The Dissociation Chemistry of Ionized Methyl Carbamate and its Isomers Revisited: Theory and Experiment in Concert Journal Articles