A CALORIMETRIC STUDY OF PHASE-TRANSITIONS FOR SOME CYCLOHEXANEDIOLS

Phase transitions in solid cis-1,2-cyclohexanediol and trans-1,2-cyclo hexanediol and cis/trans-1,4-cyclohexanediol have been studied by diff erential scanning calorimetry over the temperature range 241 to 383 K. Besides a low-temperature crystalline form, DSC curves show the exist ence of a solid rotator phase in cis-1,2-cyclohexanediol whilst for th e others, only one solid phase is present. Enthalpies of sublimation a nd vaporization were determined by evaporation into a vacuum using an isothermal calorimeter.