Ahm. Renfrew et al., TIMING OF BONDING CHANGES IN FUNDAMENTAL REACTIONS IN SOLUTIONS - PYRIDINOLYSIS OF A TRIAZINYLPYRIDINIUM SALT, Perkin transactions. 2, (12), 1994, pp. 2383-2384
Pyridinolysis of 1-(4,6-diphenoxy-1,3,5-triazin-2-yl) pyridinium chlor
ide with substituted pyridines in aqueous solution exhibits a non-line
ar Bronsted correlation possessing a break-point at the pK(a) of the p
yridine nucleophile equal to that of the leaving group: the results ar
e consistent with the intervention of a Meisenheimer-like intermediate
and the full effective charge map for solution states along the react
ion coordinate indicates substantial bonding change in the formation o
f the transition states.