Enthalpies of solution, enthalpies of fusion and enthalpies of solvation of polyaromatic hydrocarbons: Instruments for determination of sublimation enthalpy at 298.15K

Abstract

© 2015. In this work a simple method for calculation of solvation enthalpies of polyaromatic hydrocarbons (PAHs) in various solvents at 298.15. K was proposed. According to this method the enthalpy of solvation of any polyaromatic hydrocarbon in a particular solvent can be calculated on the basis of the general formula of the compound, the solvation enthalpy of benzene in the same solvent and parameter related to the contribution of hydrogen atom into solvation enthalpy. The validity of the proposed method was confirmed by the comparison of calculated and experimentally measured values of solvation enthalpies of PAHs in benzene, tetrahydrofuran and acetonitrile. This method was used for determination of the sublimation enthalpy of PAHs at 298.15. K based on the general relationship between the enthalpy of sublimation/vaporization of the compound of interest and its enthalpies of solution and solvation in the same solvent at 298.15. K. Enthalpies of solution at infinite dilution of several PAHs were measured in acetonitrile, benzene and tetrahydrofuran at 298.15. K. It was shown that solution enthalpies of PAHs in benzene at 298.15. K are approximately equal to their fusion enthalpies at the melting temperature. Solvation enthalpies of 15 PAHs at 298.15. K calculated according to the proposed method together with corresponding fusion enthalpy values (at the melting temperature) were used to calculate the sublimation enthalpy values at 298.15. K. Comparison of the obtained results with recommended values of sublimation enthalpy shows that fusion enthalpies at the melting temperature can be used instead of the solution enthalpies in benzene at 298.15. K for calculation of the sublimation enthalpy at 298.15. K.