Abstract
When thiamine-HCl in a solution of NaOH (3 moles) was reacted with NH_2OH at the room temperature, a crystalline precipitate was gradually obtained. The precipitate, purified by repeated recrystallization, was identified as the condensation-product of thiamine with NH_2OH. Diazinothiamine, C_<12>H_<17>OH_5S (dp. 281〜283℃) from the spectra of UV, IR and NMR and also elementary and mass analysis ; its chemical structure was assumed to be 4-[(2-methyl-4-amino-5-pyrimidinyl)-methyl]-5-methyl-6-(2-hydroxyethyl)-1,2,4-thiadiazine. The 1,2,4-thiadiazine compound (dp. ca. 320℃) was obtained from the 5-methyl-thiazolium homolog of thiamine and NH_2OH. Diazinothiamine was proved to be very stable in acid or alkali, there was no conversion to thiamine or its pyrimidine moiety by chemical reaction with oxidants or reductants.
