Abstract
1. Degradation of Ψ-dihydrothiamine at 35° in aqueous solution was successively investigated. It was shown to be stable in alkaline solution, but it rapidly degraded in acid solution, being partially converted to thiamine.
2. Addition of hydrogen peroxide to either n- or Ψ-dihydrothiamine in acid solution resulted in 2-methyl-4-amino-5-aminomethylpyrimidine sulfate formation.
3. Dihydrothiamine was partially converted to thiamine by addition of cyanide in a weakly acid solution. Thiocyanate showed no effect. For the reaction a large amount of cyanide as compared with dihydrothiamine was required and the dissolved oxygen accelerated the reaction, whereas hydrogen or nitrogen inhibited the reaction. These findings suggest that the reaction is a kind of air oxidation catalyzed by cyanide.
