Mechanism of the hydrogen chloride/methanol-catalyzed mutarotation reaction of N-(p-chlorophenyl)-beta-D-glucopyranosylamine

The rate of the hydrogen chloride/methanol-catalyzed mutarotation of N-(p-c hlorophenyl)-beta -D-glucopyranosylamine has been studied polarimetrically at 16, 20, 25, and 30 degreesC, Rate constants and activation parameters ha ve been determined for two parallel reactions. Enthalpies of formation, Del taH(f)(degrees), and entropies, S degrees, have been determined using the P M3 method for the various structures involved in the anomerization. The ele ctrostatic potential around the p-chloroaniline N-D-glucoside molecule has also been calculated. The differences between the experimental and calculat ed activation parameters are discussed, A relatively stable acyclic immoniu m ion was found to be an intermediate of the reaction.