Thermodynamic properties of 2 methylindole: experimental and computational results for gas-phase entropy and enthalpy of formation

Published

June 3, 2018

Author(s)

Robert D. Chirico, Yauheni Paulechka, Ala Bazyleva, Andrei F. Kazakov

Abstract

Measurements leading to the calculation of thermodynamic properties in the ideal-gas state for 2-methylindole (Chemical Abstracts registry number [95-20-5]) are reported. Experimental methods were adiabatic heat-capacity calorimetry, differential scanning calorimetry (d.s.c.), comparative ebulliometry, inclined-piston manometry, and oxygen bomb calorimetry. The critical temperature of 2-methylindole was determined experimentally with d.s.c. Molar thermodynamic functions (enthalpies, entropies and Gibbs energies) for the condensed and ideal-gas states were derived from the experimental results. Statistical calculations were performed based on molecular geometry optimization and vibrational frequencies using B3LYP hybrid density functional theory with the def2-TZVPPD basis set. Excellent accord between computed and experimentally-derived ideal-gas entropies is shown. The enthalpy of formation for 2- methylindole in the gas phase was computed with an atomization-based protocol described recently, and excellent agreement with the experiment-based values is seen. The experimental literature for enthalpies of formation in the gas phase for 1- and 2-ring pyrrollic compounds is reviewed, and comparisons with computed values further support the findings here. All experimental results are compared with property values reported in the literature, where possible.

Citation

Journal of Chemical Thermodynamics

Volume

125

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.jct.2018.05.029

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Keywords

computational chemistry, critical temperature, enthalpy of formation, entropy, heat capacity, ideal-gas properties, 2-methylindole, vapor pressure

Citation

Chirico, R. , Paulechka, Y. , Bazyleva, A. and Kazakov, A. (2018), Thermodynamic properties of 2 methylindole: experimental and computational results for gas-phase entropy and enthalpy of formation, Journal of Chemical Thermodynamics, [online], https://doi.org/10.1016/j.jct.2018.05.029 (Accessed October 11, 2025)