Substituent effects on the rates of formation of pyridinium ylides

Abstract

Pyridinium ylides are formed by deprotonation of the 2- and 6-positions of 3-substituted 1-methylpyridinium ions in D₂O buffer solutions at 75·0° in reactions catalysed by deuterioxide ion. The reactivity of the 2-position was determined for 10 substituted ions; eight ions gave kinetic results for the 6-position. Dual substituent parameter equations employing inductive and resonance effects correlate rate constants very well.