Protonated carbamic acid. Collisional activation and unimolecular dissociation of CH₄NO₂⁺

Protonated carbamic acid is generated by elimination of a vinyl radical from the radical cation of ethyl carbamate. Double hydrogen transfer leads to an excited state of the stable Y-configuration in addition to other isomers. The properties of gaseous CH4NO + 2 have been disclosed on the basis of collisional activation mass spectrometry as well as unimolecular dissociation (MIKE) in combination with an extensive use of 15N and deuterium labelling.

Thermochemical aspects of the protonated carbamic acid are discussed based on semiempirical MNDO calculations, supplementary to appearance energy measurements.