ビタミンB₁塩酸塩の多形

抄録

It was found that the thiamine hydrochloride exists in 5 crystalline phases (polymorphs and pseudopolymorphs). The most stable form is the monohydrate (I), which is common on the market. Comparison of the X-ray diffraction patterns showed that I is identical with the α-form reported previously. ³The metastable form (II) is an anhydrate and identical with the β-form in the same report. II shows a polymorphic transition at about 197° to III, which is stable at higher temperatures. III is also obtained by heating I at about 90° and is easily transformed to I by absorbing H₂O in the air. IV, the unstable phase, is obtained by recrystallization from methanol and is confirmed to be a monomethanolate. IV is transformed to V, releasing methanol slowly in the air but rapidly at about 80°. V is liable to absorb H₂O to become I in the air. All these results were deduced from X-ray diffraction, infrared absorption spectrometry, differential thermal analysis and thermogravimetric studies.