Determination of sublimation enthalpies of substituted benzophenones, fluorenes and diphenyl ethers by solution calorimetry approach

Abstract

An approach for the determination of solvation enthalpies of substituted aromatic compounds is developed. In this work the solvation enthalpy of a reference unit (benzophenone, fluorene and diphenyl ether) is calculated as the difference between solution enthalpy and sublimation enthalpy at 298K. An additive approach for the determination of solvation enthalpies of substituted aromatic compounds was used. Solvation enthalpies of sixteen substituted benzophenones, fluorenes and diphenyl ethers were calculated by this approach. Thermochemical data of solution enthalpies of benzophenones, fluorenes and diphenyl ether were measured by a precision solution calorimeter at 298K. Then sublimation enthalpies of the studied compounds were derived by a solution calorimetry (SC) approach at 298K.We have also found that in a number of cases instead of the solution enthalpy in benzene at 298K the fusion enthalpy at the melting temperature can be used. A comparison between literature data and the calculated vaporization and sublimation enthalpies demonstrates a satisfactory performance of the proposed approach.