Energetics of Quinazoline-2,4(1H,3H)-dione: An Experimental and Computational Study

• Type: Article in International Scientific Journal
• Date: 2011

Authors

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

Journal

Title: Journal of Chemical & Engineering Data

Vol. 56

Pages: 4516-4523

ISSN: 0021-9568

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 7 Citations

Scientific classification

FOS: Engineering and technology > Chemical engineering

Other information

Authenticus ID: P-002-J82

DOI: 10.1021/je2004929

Abstract (EN): In this paper we report the standard (p degrees = 0.1 MPa) molar enthalpy of formation of quinazoline-2,4(1H,3H)-dione, in the gaseous phase, at T = 298.15 K, which was derived from a combined experimental and computational thermochemical work. The static bomb combustion calorimetry technique was used to determine the standard massic energy of combustion and consequently the standard molar enthalpy of formation, in the crystalline phase, at T = 298.15 K, and the Calvet microcalorimetry technique was employed to determine the standard molar enthalpy of sublimation, at T = 298.15 K. The obtained standard molar enthalpy of formation, in the gaseous phase, at T = 298.15 K, was: Delta(f)H(m)degrees(g) = (271.1 +/- 3.3) kJ . mol(-1). In addition, quantum chemical calculations were performed using the G3(MP2)//B3LYP composite method to assess the relative energetic stabilities of quinazoline-2,4(1H,3H)-dione and its tautomers (4-hydroxyquinazolin-2(1H)-one, 2-hydroxyquinazolin-4(1H)-one, 2-hydroxyquinazolin-4(3H)-one, and quinazolin-2,4-diol). Estimates of the standard molar enthalpy of formation, in the gaseous phase, of the most stable tautomer, quinazoline-2,4(1H,3H)dione, at T = 298.15 K, were obtained from the G3(MP2)//B3LYP calculations using appropriate isodesmic reactions and were further compared with the obtained experimental value. The aromaticity of quinazoline-2,4(1H,3H)-dione has also been assessed through the evaluation and analysis of the Nucleus Independent Chemical Shifts (NICS) and their most significant components for the benzene and pyrimidine rings.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8