Thermochemical parameters of formation and vaporisation of alkanethiols: From experiment to prediction

Abstract

Alkanethiols are an important class of organic compounds and are used in materials science. In some cases, the production of materials based on alkanethiols requires knowledge of reliable values for vapour pressures and thermochemical parameters of phase transitions. Reliable enthalpies of vaporisation and enthalpies of formation in the condensed state are also required in order to obtain the enthalpy of formation in the gas phase. The experimental determination of enthalpies of formation in condensed state for sulfur-containing compounds is a challenging experimental task. The development of accurate predictive approaches is therefore a relevant task. In the present study, the available saturation vapour pressures at different temperatures and enthalpies of vaporisation of the alkanethiols were critically reviewed. In addition, the solution calorimetry method was developed and used to determine the enthalpy of vaporisation of alkanethiols. These data were also used to determine reliable experimental enthalpies of formation in the gas phase. Reliable experimental enthalpies of formation were then used to find the most accurate functional and basis set for estimation of the unknown enthalpy of formation in the gas phase using quantum chemical methods. In summary, the most consistent functional and basis set for calculating the enthalpies of formation of alkanethiols and the enthalpies of vaporisation obtained by solution calorimetry approach were used to estimate the enthalpies of formation of alkanethiols in the condensed state.