Thiamine disulfide was obtained by reacting chlorosulfonic acid ester to sodium salt of thiamine in thiol-form. When chlorosulfonic acid ester was treated to thiamine in alkaline solution to which mercaptan was existed prior to the treatment, it was found that thiamine alkyl disulfides (IX) were produced easily. The same reaction proceeded by the sulfonyl chloride, instead of chloro sulfonic acid ester.
