International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2572

Full Length Research Paper

Thermodynamic properties and relative stability of polybrominated phenoxathiins by density functional theory

C. Wang1, Z. Y. Fang1, H. Liu2* and S. Xu2
1School of Physics, Peking University, Beijing-100871, P. R. China. 2School of Biological and Chemical Engineering, Jiaxing University, Jiaxing-314001, Zhejiang, P. R. China.
Email: [email protected]

  •  Accepted: 22 October 2008
  •  Published: 31 October 2008


The thermodynamic properties of 135 polybrominated phenoxathiins (PBPTs) in the ideal gas state at 298.15 K and 1.013×105 Pa have been calculated at the B3LYP/6-31G* level using Gaussian 03 program. The isodesmic reactions were designed to calculate standard enthalpy of formation (ΔfHÓ©) and standard free energy of formation (ΔfGÓ©) of PBPTs congeners. The relations of these thermodynamic parameters with the number and position of Br atom substitution (NPBS) were discussed, and it was found that there exist good correlations between thermodynamic parameters (entropy (SÓ©), ΔfHÓ© and ΔfGÓ©) and NPBS. According to the relative magnitude of their ΔfGÓ©, the order of relative stability of PBPT congeners was theoretically proposed. Moreover, using a statistical thermodynamics calculation program based on Gaussian output files, the values of molar heat capacity at constant pressure (Cp,m) from 200 to 1800 K for PBPT congeners were calculated, and the temperature dependence relation of them was obtained using the least-squares method.


Key words: Polybrominated phenoxathiins, the number and position of Br atom substitution (NPBS), thermodynamic property, relative stability, molar heat capacity at constant pressure (Cp,m).