抄録
By an alkaline ferricyanide solution, thiamine was oxidized into thiochrome and thiamine disulfide in different proportions which were variable according to pH of the solution. Moreover, dissolved oxygen in the solution gave a considerable influence to stimulate formation of thiamine disulfide and inhibit oxidation to thiochrome. But at pH between 11-12 formation of thiamine disulfide was predominant even at the exclusion of oxygen by saturating N_2 in the solution. At pH over 13,formation of thiochrome from 10μg thiamine was 83% to the theoretical value in the N_2-saturated solution and 58% in the O_2-saturated solution. If the O_2-saturated solution of thiamine was replaced by N_2,the yield of thiochrome was recovered as high as that of the initially N_2-saturated solution. Dissolved oxygen or its exclusion by N_2-saturation gave no influence to the absorption at 340mμ of an alkaline thiamine solution. So an assumed intermediate showing absorption at 340mμ would not be a key substance to formation of thiochrome, however dissolved oxygen will push the reaction to form thiamine disulfide and exclusion of oxygen makes it favorable to form thiochrome.
