Abstract
Formation of Schiff bases of pyridoxal with glycine and glycinamide in methanol were studied kinetically by the changes of electronic absorption spectra. When glycine or glycinamide was added to carbinolamine formed from pyridoxal and sarcosine, Schiff base was also formed. Both sarcosine catalyzed and direct (under sarcosine-free) Schiff base formation followed the first order kinetics as long as amines were excess over pyridoxal. From variations of the pseudo first order rate constants with acid-alkaline concentration, following conclusions were obtained ; in direct Schiff base formation of glycine, rate determining step was dehydration in acidic region and carbinolamine formation in neutral and alkaline methanol ; in the case of glycinamide, carbinolamine formation was always rate determining step. Formation of Schiff base of glycine from Schiff base of glycinamide and glycine, transaldimination, was rapid reaction.
