モノグリセリドの多形 (第1報) : 1-モノラウリン, 1-モノミリスチン, 1-モノパルミチンおよび1-モノステアリンの結晶変態の転移について

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1-Monolaurin, 1-monomyristin, 1-monopalmitin and 1-monostearin of over 99% in purity were synthesized and their polymorphic phenomena were examined by differential thermal analysis, and its results were compared with those from infrared absorption spectra and X-ray diffraction. Crystal modification was examined by polarization microscope and electron microscope with those having polymorphic crystals as confirmed by X-ray diffraction. 1) Monoglycerides precipitated out very gradually from the solvent, showed only one melting peak and the peak temperature agreed with that of the β form in literature. 2) Quenched sample showed variation in endothermic peak with increasing time of heat treatment, and endothermic corresponding to sub-α, α, β and β were obtained. 3) The time required for transition became faster in the order of monolaurin, monomyristin, monopalmitin and monostearin. Transition was detected earlier in the differential thermal analysis than by infrared absorption spectrum or X-ray diffraction, perhaps due to tempering effect during the measurement. 4) T-T-T curve (transition curves) from (sub-α+α+β) to β form of monolaurin and monostearin showed a point of inflexion at 16°C and 31°C, respectively. Transition of (sub-α+α) to β form of monopalmitin and monostearin also showed a point of inflexion, but in that of β form to β form it indicated a fairly characteristic difference according to the number of carbon atoms. 5) Reversible transition between sub-α and α form was confirmed even by differential thermal analysis by repeating cooling and heating. 6) Results of observation through polarization microscope and electron microscope on four kinds of crystal modification confirmed by X-ray diffraction revealed that fine anisotropic crystal in sub-α grew into rhombic crystals on thermal stable state as transition progressed.

モノグリセリドの多形 (第1報) : 1-モノラウリン, 1-モノミリスチン, 1-モノパルミチンおよび1-モノステアリンの結晶変態の転移について

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