ピリジン-およびピラジン-モノカルボン酸アミドの溶解現象 (第1報)

ピコリン酸アミド, ニコチン酸アミド, イソニコチン酸アミド, およびピラジンカルボン酸アミドの昇華熱

抄録

In order to understand the solubility phenomena of monocarboxamides of pyridine and pyrazine by application of the regular solution theory, heat of sublimation was calculated from molecular effusion method (Table II). The samples were purified by low-pressure sublimation at temperatures below the melting point and absence of any changes in crystal system before and after sublimation was confirmed through X-ray diffraction (Table III). However, pyrazine-monocarboxamide shows, even below its melting point but above 160°, a crystal system different from that of the starting material or that below 160°, and this suggests phase rearrangement (cf. Part II of this series). Heat of evaporation of three kinds of picolylamine, corresponding to acid amide, was measured by molecular effusion method (Table V) and the degree of its reaction was found to be in the decreasing order of 2-, 4-, and 3-, as in the case of acid amides. From the difference of these values, energy of one hydrogen bond of NH…O was presumed (Table VI).