Vitamin B₁及び諸関係化合物の研究 第70報

Dihydrothiamineについて

抄録

Reaction of equimolar amounts of 2-methyl-4-amino-5-aminomethylpyrimidine (IV), γ-aceto-γ-mercaptopropyl alcohol (V), and formaldehyde, in dil. ethanol, results in the formation of dihydrothiamine (II), m.p. 150°, in a good yield, and (II) is identical with the sample obtained by reduction of thiamine (I) with lithium aluminum hydride. When the foregoing reaction is carried out in the presence of sodium hydroxide or on the application of sodium hydroxide on (II), isodihydrothiamine, m.p. 160°, is formed. Solvation of dihydro- or isodihydro-thiamine in water with application of heat converts them into pseudodihydrothiamine. Both iso- and pseudo-dihydrothiamines possess the same composition and molecular weight as those of dihydrothiamine, show the same Rf values, and give identical reactions.
Application of (V) to the condensate (VI) from equimolar reaction of (IV) and formaldehyde also yields (II) or its isomer. Thiamine is formed from (II) by the application of ferric chloride, sodium nitroprusside, or potassium ferricyanide. Warming the solution of (II) in hydrochloric acid effects its complete decomposition and formation of (VI). The same treatment psudo- or iso-dihydrothiamine gives the same results, forming thiamine or (VI).