Calorimetric and Computational Study of the Thermochemistry of Phenoxyphenols

• Tipo: Artigo em Revista Científica Internacional
• Data: 2011

Autores

da Silva, MAVR (Autor) FCUP; Ana I M C L Lobo Ferreira (Autor) FCUP; Cimas, A (Autor) Outra

Revista

Título: Journal of Organic Chemistry

Vol. 76

Páginas: 3754-3764

ISSN: 0022-3263

Editora: American Chemical Society

Indexação

ISI Web of Knowledge - 8 Citações

Scopus - 7 Citações

Outras Informações

ID Authenticus: P-002-RDX

DOI: 10.1021/jo200018r

Abstract (EN): Thermodynamic properties of 3- and 4-phenoxyphenol have been determined by using a combination of calorimetric and effusion techniques as well as by high-level ab initio molecular orbital calculations. The standard (p degrees = 0.1 MPa) molar enthalpies of formation in the condensed and gas states, Delta(f)H(m)degrees(cr or 1) and Delta(f)H(m)degrees(g), at T = 298.15 K, of 3- and 4-phenoxyphenol were derived from their energies of combustion in oxygen, measured by a static bomb calorimeter, and from the enthalpies of vaporization or sublimation derived respectively by Calvet microcalorimetry for the 3-phenoxyphenol and, by Knudsen effusion technique for the 4-phenoxyphenol. The theoretically estimated gas-phase enthalpies of formation were calculated from high-level ab initio molecular orbital calculations at the G3(MP2)//B3LYP level of theory. Furthermore, this composite approach was also used to obtain information about the gas-phase acidities, gas-phase basicities, proton and electron affinities, adiabatic ionization enthalpies, and, finally, O-H bond dissociation enthalpies. The good agreement between the G3MP2B3-derived values and the experimental gas-phase enthalpies of formation for the 3- and 4-phenoxyphenol gives confidence to the estimate concerning the 2-phenoxyphenol isomer, which was not experimentally studied, and to the estimates concerning the radical and the anion. Additionally, the experimental values of gas-phase enthalpies of formation were also compared with estimates based on the empirical scheme developed by Cox.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11