Gas phase enthalpies of formation of monobromophenols

• Tipo: Artigo em Revista Científica Internacional
• Data: 2009

Autores

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

Revista

Título: Journal of Chemical Thermodynamics

Vol. 41

Páginas: 1104-1110

ISSN: 0021-9614

Editora: Elsevier

Indexação

ISI Web of Knowledge - 19 Citações

Scopus - 16 Citações

Outras Informações

ID Authenticus: P-003-FEA

DOI: 10.1016/j.jct.2009.04.017

Abstract (EN): The standard (p degrees = 0.1 MPa) molar enthalpies of formation of the liquid 2-bromophenol and crystalline 4-bromophenol, respectively, Delta(f)H(m)degrees(l) = -(133.5 +/- 1.4) kJ . mol(-1) and Delta(f)H(m)degrees(cr) = -(152.4 +/- 1.4) kJ . mol(-1), were derived from the standard molar energies of combustion, in oxygen, to yield CO(2)(g) and HBr center dot 600H(2)O(l), at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpy of vaporization or sublimation of the compounds, Delta(g)(l)H(m)degrees = (55.5 +/- 1.3) kJ . mol(-1) and Delta(g)(cr)H(m)degrees = (83.1 +/- 1.6) kJ . mol(-1). These two thermodynamic parameters yielded the standard molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, of 2- and 4-bromophenol, respectively, Delta(f)H(m)degrees(g) = -(78.0 +/- 1.9) kJ . mol(-1) and Delta(f)H(m)degrees(g) = -(69.3 +/- 2.1) kJ . mol(-1). The experimental values of the gas-phase enthalpies of formation of each compound were compared with estimates using the empirical scheme developed by Cox and with the calculated values based on high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional at the 6-311++G(d,p) basis set.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7