Theoretical study of the relative reactivity of chloroethenes with atmospheric oxidants (OH, NO3, O(3P), Cl(2P) and Br(2P)

BAUMGARTNER, M.T.; TACCONE, R.A.; TERUEL, M.A.; LANE, S.I.

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

Royal Society of Chemistry

Lugar: london; Año: 2002 vol. 4 p. 1028 - 1032

1463-9076

The reactivity of a series of chloroethenes with different electrophiles of tropospheric and stratospheric interest is analyzed by frontier molecular orbital theory and a correlation with calculated orbital energies is investigated. The reactions of CH2=CHCl; CH2=CCl2; (Z)-CHCl=CHCl; (E)-CHCl=CHCl; CHCl=CCl2 and CCl2=CCl2 with O(3P), Cl(2P), Br(2P) atoms and with OH and NO3 radicals were studied using semiempirical methods (AM1 and PM3) and ab-initio calculations at the HF and B3LYP levels of theory with the 6-31G** basis set, using the Gaussian-98 suite of programs. In contrast to the majority of reaction series of small radicals and molecules with alkenes and alkanes, the rate constants for the reactions with halogenated ethenes do not correlate with the ionization potential of the halogenated ethene. The energy and the carbon-carbon -bonding form of the HOMO change by adding chlorine atoms as substituents to the carbon-carbon -bonding framework of the alkenes. For the reactions studied in this work the complete interaction HOMO-SOMO was considered taking into account the contribution of the different atomic orbitals to the HOMO of the chloroethene through the atomic orbital coefficients and a good correlation with the experimental values was obtained.