Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Current study presents vapour pressure curves and from these derived normal boiling points and heats of vaporisations at normal boiling points for three alkylresorcinols: 2-n-propylresorcinol, 4-ethylresorcinol, 4-hexylresorcinol. Measurements were made near their boiling points, i.e. bracketing the normal boiling points. A differential scanning calorimeter (DSC) was used for measuring vapour pressure, by which the compound's boiling point was determined at various selected pressures following the procedure recommended by the ASTM E1782 standard. The experiments were carried out using hermetically sealable pans, that had pinholes with diameter of 50 mum in the lids, and a heating rate of 5 K*min-1. Antoine equation constants were derived to describe vapour pressure behaviours in temperature ranges of the measurements, which were 480.5 K to 629.3 K for 4-ethylresorcinol, 470.5 K to 618.9 K for 2-n-propylresorcinol, and 517.8 K to 651.0 K for 4-hexylresorcinol. The normal boiling points were found to be (605.4 +- 0.4) K for 4-hexylresorcinol, (561.8 +- 0.5) K for 4-ethylresorcinol and (552.5 +- 0.5) K for 2-n-propylresorcinol. The heats of vaporisations at normal boiling points were calculated to be (65.8 +- 0.5, 60.9 +- 0.5 and 58.6 +- 0.4) kJ*mol-1 respectively. In addition some indicative lower accuracy vapour pressure data were measured for resorcinol and catechol at lower pressures (1.3-5.3) kPa (three data points), and for 4-hexylresorcinol at (1.95-7.89) kPa (5 data points).