A thermochemical and theoretical study of the phenylpyridine isomers

• Type: Article in International Scientific Journal
• Date: 2000

Authors

da Silva, MAVR (Author) FCUP; Matos, MAR (Author) FCUP; Rio, CA (Author) Other; Morais, VMF (Author) ICBAS; Wang, J (Author) Other; Nichols, G (Author) Other; Chickos, JS (Author) Other

Journal

Title: Journal of Physical Chemistry A

Vol. 104

Pages: 1774-1778

ISSN: 1089-5639

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 31 Citations

Scopus - 32 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-001-0KX

Abstract (EN): The standard (p degrees = 0.1 MPa) molar enthalpies of formation for 2-, 3-, and 4-phenylpyridine in the, gas phase were derived from the standard molar enthalpies of combustion, in oxygen, at 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of vaporization for 2-, 3-, and 4-phenylpyridine at T = 298.15 K were measured by correlation-gas chromatography. The enthalpy of sublimation of 4-phenylpyridine was obtained as a weighted mean of the value derived from the vaporization and fusion enthalpy values and the value measured directly by Calvet microcalorimetry. The following enthalpies of formation were then derived: 2-phenylpyridine, g = 228.3 +/- 5.8 kJ.mol(-1); 3-phenylpyridine, g = 240.9 +/- 5.5 kJ.mol(-1); 4-phenylpyridine, g = 240.0 +/- 33 kJ.mol(-1). The most stable geometries of all phenylpyridine isomers were obtained using both restricted Hartree-Fock (RHF) and density functional theory (DFT/B3LYP) methods. The resulting geometries were then used to obtain estimates of enthalpies of formation of the three isomers of phenylpyridine, which are in good agreement with the experimental values. A theoretical interpretation of the effect of the phenyl ring has on the relative stabilities of the three molecules is presented.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 5