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Gas-phase fragmentation of protonated benzodiazepines
Antonella Risoli1, Joey B Y Cheng, Udo H Verkerk
1Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3.
Abstract:
Protonated 1,4-benzodiazepines dissociate in the gas phase by the common pathway of CO elimination and by unique pathways dictated by the substituents; the latter typically differentiate one benzodiazepine from another. Protonated 3-dihydro-5-phenyl-1,4-benzodiazepin-2-one, the base diazepam devoid of substituents, dissociates by eliminating CO, HNCO, benzene, and benzonitrile. Mechanisms of these reactions are proposed with ionic products being resonance stabilized. The abundant [MH-CO]+ ion dissociates to secondary products via elimination of benzene, benzonitrile, the NH2 radical, and ammonia, yielding again ionic products that are stabilized by resonance.
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