Thermodynamic properties of three-ring aza-aromatics.2. Experimental results for 1,10-phenanthroline, phenanthridine, and 7,8-benzoquinoline, and mutual validation of experiments and computational methods

Published

November 18, 2009

Author(s)

Robert D. Chirico, Andrei F. Kazakov, William V. Steele

Abstract

Measurements leading to the calculation of standard entropies for 1,10-phenanthroline (Chemical Abstracts registry number [66-71-7]) in the crystal, liquid, and ideal-gas state are reported. Experimental methods were adiabatic heat-capacity calorimetry and comparative ebulliometry. Thermodynamic properties for phenanthridine [229-87-8] and 7,8-benzoquinoline [230-27-3] were reported previously and included those measured with adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston manometry, and combustion calorimetry. New measurement results for phenanthridine and 7,8-benzoquinoline reported here are densities determined with a vibrating-tube densimeter and heat capacities for the liquid phase at saturation pressure determined with a differential-scanning calorimeter (dsc). All critical properties were estimated. Molar entropies for the ideal gas state were derived for all compounds at selected temperatures. Independent calculations of entropies for the ideal-gas state were performed at the B3LYP/6-31+G(d,p) model chemistry for the three compounds studied. These are shown to be in excellent accord with the calorimetric results for 1,10-phenanthroline and phenanthridine. Results for 7,8-benzoquinoline indicate that the crystal state is disordered. All new experimental results are compared with property values reported in the literature.

Citation

Journal of Chemical Thermodynamics

Volume

42

Pub Type

Journals

Keywords

1, 10-phenanthroline, 7, 8-benzoquinoline, phenanthridine, heat capacity, vapor pressure, density, ideal-gas properties, computational chemistry, entropy, disorder

Citation

Chirico, R. , Kazakov, A. and Steele, W. (2009), Thermodynamic properties of three-ring aza-aromatics.2. Experimental results for 1,10-phenanthroline, phenanthridine, and 7,8-benzoquinoline, and mutual validation of experiments and computational methods, Journal of Chemical Thermodynamics (Accessed October 22, 2025)