PIPERIDINO AND PYRROLIDINO DEMETHOXYLATION OF 4-METHOXY-1-METHYL-2, 6-DIPHENYLPYRIDINIUM ION. RATE PARAMETERS AND BASE CATALYSIS.

Article abstract of DOI:10.1021/ja00355a024

The kinetics of pyrrolidino and piperidino demethoxylation of 4-methoxy-1-methyl-2,6-diphenylpyridinium ion have been studied in methanol in the presence of the corresponding amine/ammonium buffers, at 25 degree C. The reactions display general base catalysis, as observed for the reactions with the nitroactivated benzene systems, and a kinetic pattern similar to that previously found when morpholine is used. A determination of a consistent set of pK//a values for the amines in methanol has been required and has allowed a clarification concerning morpholine in connection with some recent misleading reports. The kinetic analysis includes the evaluation of a number of significant parameters and is combined with the effect of the diverse basicity of the three amines. A specific base-general acid (SB-GA) mechanism is indicated as the most likely reaction path common to the investigated reactions.