3-Substituted 1-methoxypyridinium ions: substituent effects on rates of hydrogen-deuterium exchange

Pyridinium ylides are formed by deprotonation of the 2- and 6-positions of 3-substituted 1-methoxypyridinium ions in heavy water buffer solutions at 75.0/sup 0/C in reactions catalyzed by deuterioxide ion. Dual substituent parameter equations employing inductive and resonance effects correlate rate constants very well. Both 1- and 3-substituents have an additive influence on the reactivity of the 2-position even when reactivity approaches a diffusion-controlled limit. 1 figure, 2 tables.