Benzonitrile assisted enolization of the acetone and acetamide radical cations: proton-transport catalysis versus an intermolecular H+/· transfer mechanism11Dedicated to Professor Nico Nibbering on the occasion of his imminent retirement, in appreciation of his seminal contributions to the field of gas-phase ion chemistry.

The acetamide radical cation, CH3C(O)NH2·+, can be induced to rearrange into its more stable enol isomer, CH2C(OH)NH2·+, by an ion–molecule interaction with benzonitrile, C6H5CN, under conditions of chemical ionization. (This enolization does not occur unassisted because of a prohibitively high energy barrier: 26 kcal/mol, from a CBS-QB3 calculation.) The initially formed [C6H5CN ⋯ acetamide]·+ adduct ion isomerizes to a stable hydrogen …