3,4,5-trimethoxyphenol: A combined experimental and theoretical thermochemical investigation of its antioxidant capacity

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Agostinha A R Matos (Author) FCUP; Margarida S Miranda (Author) Other; Victor M F Morais (Author) ICBAS

Journal

Title: Journal of Chemical Thermodynamics

Vol. 40

Pages: 625-631

ISSN: 0021-9614

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 15 Citations

Scopus - 15 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-004-0JE

DOI: 10.1016/j.jct.2007.11.006

Abstract (EN): The standard (p degrees = 0.1 MPa) molar enthalpies of combustion and sublimation of 3,4,5-trimethoxyphenol were measured, respectively, by static bomb combustion calorimetry in oxygen atmosphere and by Calvet microcalorimetry. From these measurements, the standard molar enthalpy of formation in both the crystalline and gaseous phase, at T = 298.15 K, were derived: -(643.4 +/- 1.9) kJ . mol(-1) and -(518.1 +/- 3.6) kJ . mol(-1), respectively. Density functional theory calculations for this compound and respective phenoxyl radical and phenoxide anion were also performed using the B3LYP functional and extended basis sets, which allowed the theoretical estimation of the gaseous phase standard molar enthalpy of formation through the use of isodesmic reactions and the calculation of the homolytic and heterolytic O-H bond dissociation energies. There is good agreement between the calculated and experimental enthalpy of formation. Substituent effects on the homolytic and heterolytic O-H bond dissociation energies have been analysed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7