Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

The enthalpies of vaporization of several trialkyl phosphates such as, tri-n-butyl phosphate (TBP), triisobutyl phosphate (TiBP), tri-secondary butyl phosphate (TsBP), tri-n-amyl phosphate (TAP), triisoamyl phosphate (TiAP), Tri-2-methyl butyl phosphate (T2MBP), tri-secondary amyl phosphate (TsAP), and trihexyl phosphate (THP) have been measured for the first time using correlation gas-chromatographic technique. Normal paraffin hydrocarbons have been used as references after demonstrating the suitability of them by determining the enthalpies of vaporization of trimethyl phosphate (TMP) and triethyl phosphate (TEP) for which data is available in the literature. The vaporization enthalpies were correlated to structural parameters characterizing the compounds studied. Solvent accessible surface area (SAS), among the parameters, was found to exhibit excellent correlation to the enthalpies of vaporization of trialkyl phosphates as well as the normal paraffin hydrocarbons used as the reference. The Hildebrand s solubility parameters for the trialkyl phosphates were derived from the values of enthalpy of vaporization at 298.15 K.