Tosyl oxygen transfer and ion–neutral complex mediated electron transfer in the gas-phase fragmentation of the protonated N-phenyl p-toluenesulfonamides

•Tosyl oxygen transfer.•INC-mediated electron transfer.•Differentiation of isomeric N-methylphenyl p-toluenesulfonamides.

In this work, an interesting oxygen transfer reaction in the gas phase dissociation of N-phenyl p-toluenesulfonamides has been explored by combination of the ESI–MS techniques and theoretical calculations. The protonated molecules underwent dissociation reactions, upon collisional activation, to give the [tosyl cation/aniline] ion–neutral complex (INC), in which the coupling reactions subsequently occurred to afford an ionic species of toluenesulfinate. The subsequent reactions of the toluenesulfinate species resulted in generation of the protonated 6-iminocyclohexa- 2,4-dienone or the 2-aminophenol radical cation, via cleavage of the SO bond. The above processes involved the tosyl oxygen transfer, and calculation results indicated that both the ortho- and the para- positions at the aniline ring are favorite for the tosyl oxygen transfer, and formation of radical cation involved an INC mediated electron transfer. The isomeric N-methylphenyl p-toluenesulfonamides behaved significant difference in the CID–MS spectra, indicating that the three isomers can be distinguished by ESI–MS.

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