Abstract
In the presence of isoniazid methanesulfonate sodium (I), decomposition of thiamine in solution was shown to proceed at an increased rate with a decrease in acidity through a maximum at pH 5-5.5. Activation energy for this reaction was found to be 20.7kcal/mole. Isolation of the main reaction product, 1-(2-methyl-4-amino-5-pyrimidyl) methyl-4-sulfo-methylhydrazinocarbonyl pyridinium chloride, showed that thiamine was decomposed by the replacement reaction of the thiazole moiety of thiamine with I in the presence of bisulfite from I. In addition, a replacement reaction product of thiamine, 1-isonicotinyl-2-(2-methyl-4-amino-5-pyrimidyl) methyl hydrazine (II) was obtained. However, the yield of II was low when compared with the result of the reaction of thiamine with isoniazid in the presence of bisulfite. This may be attributable to the small degree of dissociation of I. The results obtained with these experiments and those previously reported, suggest that such N-methanesulfonate compounds as sulpyrine and I may affect the stability of thiamine in a similar manner.
