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

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

Authors

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

Journal

Title: Journal of Chemical Thermodynamics

Vol. 40

Pages: 1378-1385

ISSN: 0021-9614

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 17 Citations

Scopus - 18 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: 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).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8