Mass-spectrometric study on ion-molecule reactions of CH5+, C2H5+, and C3H5+ with benzoic acid and benzoates

The gas-phase ion-molecule reactions of CH5+, C2H5+, and C3H5+ with PhCOOX = M (X = H, CH3, C2H5, and Ph) have been studied under a reactant-ion selec tive chemical ionization mode of an ion-trap type of GC/MS. The major produ ct channel is non-dissociative proton transfer leading to (M+H)(+) in most cases. Dissociative proton transfer leading to (M + H - CO2)(+) and/or (M H - XOH)(+) competes with the above channels. In the C3H5 (+)/PhCOOX (X = H, CH3, and C2H5) reactions, initial (M + C3H5)(+) adduct ions and/or their decomposition products are found. The reaction mechanism is discussed base d on the reaction-time dependence of product-ion distributions and semi-emp irical calculations of the energies of intermediates and products.