Thermochimica Acta, Vol.286, No.2, 307-319, 1996
Mixtures of D-Carvone and L-Carvone .3. Thermodynamic Properties of L-Carvone
In this study, the thermodynamic properties of l-carvone have been examined. DSC experiments and adiabatic calorimetry supplied complementary data on the complex polymorphic behaviour. Heating a supercooled sample results in a glass transition at 171 K; next a crystallisation to metastable (II) material takes place, followed by a recrystallisation to stable (I) material, and finally, the melting of the sample. The polymorphic modifications II and I are monotropic forms. The molar heat capacities of stable (I) l-cavone have been measured from 5 to 280 K. They show a reversible phase transition ’I beta to I alpha’ between 190 and 215 K, which is an enantiotropic transition, The melting temperature of the I alpha phase is 249.5 K. The heat of melting is 11.73 kJ mol(-1). The crystallisation behaviour of supercooled liquid to metastable (II) material has been studied under adiabatic conditions. The obtained curves of temperature against time may be of use in judging the kinetics of phase change at the beginning of the crystallisation process.