Thermodynamic properties of thiourea + hydrocarbon adducts from 12 to 300 K. The heat capacities and entropies of the adducts of c-C 6H 12, c-C 7H 14, c-C 8H 16, and (CH 3) 3C·C 2H 5

Abstract

Heat capacity measurements on the adducts of thiourea with cyclohexane, cycloheptane, cyclo-octane, and 2,2-dimethylbutane have been made over the temperature range 12 to 300 K by means of an adiabatic calorimeter. All the samples showed several regions of anomalously high heat capacity. Some of the smaller anomalies are suggestive of displacive ferroelectric transitions. The curve for the cyclo-octane adduct showed a large hump with its maximum at 240 K and having an associated molar enthalpy of c-C 6H 16 of 7186 J mol −1 and entropy of 31.86 J K −1 mol −1, which is here ascribed to conformational changes of the cyclo-octane; a smaller and more gradual hump in the curve for the cycloheptane adduct may be due to a similar cause.