Abstract
5-Phenoxymethy1-2-oxazolidinone (PM0) has been known to show dimorphism (melting points 115 °C and 123 °C). Aqueous recrystallization gave a mixture of both forms, however, stable high-melting form was obtained from organic solutions or cooling of melted (119 °C)sample. Low-melting form was isolated by sublimation over 250 °C or rapid solidification of melted (150 °C) sample. According to DSC measurement, heat of fusion was 26 kJ/mol for the low-melting form, and 31 kJimpl for the high-melting form. Heat of transformation from low- to high-melting form was 24 kJ/mol. Microscopic observation also recognized the thermal transformation between the both forms as shown by the DSC experiments.
