Thermodynamic properties of alkyl 1H-indole carboxylate derivatives: A combined experimental and computational study

• Type: Article in International Scientific Journal
• Date: 2016

Authors

Carvalho, TMT (Author) Other; Amaral, LMPF (Author) FCUP; Morais, VMF (Author) Other; Maria D M C R Ribeiro da Silva (Author) FCUP

Journal

Title: Journal of Chemical Thermodynamics

Vol. 97

Pages: 70-82

ISSN: 0021-9614

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 7 Citations

Other information

Authenticus ID: P-00K-4SH

DOI: 10.1016/j.jct.2016.01.006

Abstract (EN): The standard (p(o) = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, of methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate, at T = 298.15 K, were derived from measurements of the standard massic energies of combustion using a static bomb combustion calorimeter. The Knudsen effusion technique was used to measure the vapour pressures as a function of the temperature, which allowed determining the standard molar enthalpies of sublimation of these compounds. The standard (p(o) = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, were calculated by combining, for each compound, the standard molar enthalpy of formation, in the crystalline phase, and the standard molar enthalpy of sublimation, yielding -(207.6 +/- 3.6) kJ.mol (1) and -(234.4 +/- 2.4) kJ.mol (1), for methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate, respectively. Quantum chemical studies were also conducted, in order to complement the experimental study. The gas-phase enthalpies of formation were estimated from high level ab initio molecular orbital calculations, at the G3(MP2) level, for the compounds studied experimentally, extending the study to the methyl 1H-indole-2-carboxylate and ethyl 1H-indole-3-carboxylate. The results obtained were compared with the experimental data and were also analysed in terms of structural enthalpic group contributions.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13