Mechanism study of SO2 elimination from sulfonamides by negative electrospray ionization mass spectrometry

The elimination of SO(2) from deprotonated sulfonamides in the negative ion mode was confirmed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) experiments. For a set of N-arylbenzenesulfonamides substituted at the para position of the arylamine, the In([M-H-SO(2)]-/[M-H](-)) values were correlated with the sigma(-)(p) substituent constants but, instead of a linear relationship ship, a bent line was obtained. Analyses of the complex curve led to the identification of two competing routes, which were further investigated by Hartree-Fock theoretical calculations. Furthermore, collision-induced dissociation (CID) of deprotonated N-alkylbenzenesulfonamides containing the -CHCHNHSo(2)- structure yielded a [M-H-66](-) product ion This characteristic ion could help to distinguish the side-chain isomers. Copyright (C) 2008 John Wiley & Sons, Ltd.