Energetics of 2-and 3-coumaranone isomers: A combined calorimetric and computational study

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Clara C S Sousa (Author) FCUP; Agostinha A R Matos (Author) FCUP; Luis M N B F Santos (Author) FCUP; Victor M F Morais (Author) ICBAS

Journal

Title: Journal of Chemical Thermodynamics

Vol. 67

Pages: 210-216

ISSN: 0021-9614

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 9 Citations

Scopus - 8 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-006-66Q

DOI: 10.1016/j.jct.2013.08.012

Abstract (EN): Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for 2-coumaranone and 3-coumaranone were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by mini-bomb combustion calorimetry. Standard molar enthalpies of sublimation of both isomers were determined by Calvet microcalorimetry. These results were combined to derive the standard molar enthalpies of formation of the compounds, in gas phase, at T = 298.15 K. Additionally, accurate quantum chemical calculations have been performed using DFT methods and high level composite ab initio calculations. Theoretical estimates of the enthalpies of formation of the compounds are in good agreement with the experimental values thus supporting the predictions of the same parameters for isobenzofuranone, an isomer which has not been experimentally studied. The relative stability of these isomers has been evaluated by experimental and computational results. The importance of some stabilizing electronic intramolecular interactions has been studied and quantitatively evaluated through Natural Bonding Orbital (NBO) analysis of the wave functions and the nucleus independent chemical shift (NICS) of the studied systems have been calculated in order to study and establish the effect of electronic delocalization upon the relative stability of the isomers.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7