Abstract
Relative fragmentation energies of a variety of
N
-acylpyridinium cations have been measured in the gas phase by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS).
N
-Aroyl- and
N
-heteroaroyl-pyridinium cations dissociated to give free ArCO
+
ions with activation energies which are strongly decreased/increased by stabilizing/destabilizing electron-donor/acceptor substituents in the aroyl group.
N
-Alkylcarbonyl- and
N
-phenoxycarbonyl-pyridinium cations fragment
via
ion molecule complexes which dissociate to pyridinium cation and ketene or CO
2
+ aryne.
N
-Alkoxycarbonylpyridinium cations form pyridinium cations
via
detectable
N
-carboxypyridinium cations. The propensity of those cations to undergo S
N
1 or S
N
2 reactions is discussed.