Structural studies of cyclic ureas: 2. Enthalpy of formation of parabanic acid

• Tipo: Artigo em Revista Científica Internacional
• Data: 2008

Autores

Maria das Dores C R Ribeiro da Silva (Autor) FCUP; Manuel A V R Ribeiro da Silva (Autor) FCUP; Vera L S Freitas (Autor) Outra; Maria Victoria Roux (Autor) Outra; Pilar Jimenez (Autor) Outra; Juan Z Davalos (Autor) Outra; Pilar Cabildo (Autor) Outra; Rosa M Claramunt (Autor) Outra; Jose Elguero (Autor) Outra

Revista

Título: Journal of Chemical Thermodynamics

Vol. 40

Páginas: 1378-1385

ISSN: 0021-9614

Editora: Elsevier

Indexação

ISI Web of Knowledge - 17 Citações

Scopus - 18 Citações

Classificação Científica

FOS: Ciências da engenharia e tecnologias > Engenharia mecânica

Outras Informações

ID Authenticus: P-003-WK1

DOI: 10.1016/j.jct.2008.05.006

Abstract (EN): Thermophysical and thermochemical studies have been carried out for crystalline parabanic acid. The thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = (263 and 473) K. Two phase transitions were found: at T = (392.3 +/- 1.6) K with the enthalpy of transition of (2.1 +/- 0.4) kJ . mol(-1) and at T = (509.8 +/- 1.5) K, when the compound was scanned to its fusion temperature. The standard (p degrees = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for crystalline parabanic acid was determined using static-bomb combustion calorimetry as -(590.2 +/- 1.0) kJ . mol(-1). The standard molar enthalpy of sublimation, at T = 298.15 K, was derived from the variation of their vapour pressures, measured by the Knudsen-effusion method, with the temperature. These two thermochemical parameters yielded the standard molar enthalpy of formation in the gaseous phase, at T = 298.15 K, as -(470.8 +/- 1.2) kJ . mol(-1).

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 8