Kinetic of the Recombination Reactions of CFCl with CF2 and with CFCl

N. E. CABALLERO; E. CASTELLANO; C. J. COBOS; A. E. CROCE; G. A. PINO

CHEMICAL PHYSICS

ELSEVIER SCIENCE BV

Año: 1999 vol. 246 p. 157 - 166

0301-0104

The laser flash photolysis–absorption technique has been used to study the CClFqCF2qMªC2ClF3qM and CClFqCClFqMªC2Cl2F2qM recombination reactions at 297 K. Both reactions were found to be essentially at the second-order regime from 10 Torr of the CClF and CF2radicals precursor C2ClF3, up to 750 Torr of mixtures of C2ClF3rHe. The derived limiting high-pressure rate coefficients are9"2.=10y13 and1.2"0.2.=10y12 cm3 moleculey1qCF2qMªC2ClF3qM and CClFqCClFqMªC2Cl2F2qM recombination reactions at 297 K. Both reactions were found to be essentially at the second-order regime from 10 Torr of the CClF and CF2radicals precursor C2ClF3, up to 750 Torr of mixtures of C2ClF3rHe. The derived limiting high-pressure rate coefficients are9"2.=10y13 and1.2"0.2.=10y12 cm3 moleculey1qCClFqMªC2Cl2F2qM recombination reactions at 297 K. Both reactions were found to be essentially at the second-order regime from 10 Torr of the CClF and CF2radicals precursor C2ClF3, up to 750 Torr of mixtures of C2ClF3rHe. The derived limiting high-pressure rate coefficients are9"2.=10y13 and1.2"0.2.=10y12 cm3 moleculey12radicals precursor C2ClF3, up to 750 Torr of mixtures of C2ClF3rHe. The derived limiting high-pressure rate coefficients are9"2.=10y13 and1.2"0.2.=10y12 cm3 moleculey12ClF3rHe. The derived limiting high-pressure rate coefficients are9"2.=10y13 and1.2"0.2.=10y12 cm3 moleculey1 sy1, respectively. An analysis in terms of the ab initio density functional theory and the statistical adiabatic channel modelSACM.indicates that the formation of chlorine atoms by unimolecular decomposition of the initially formed C2ClF3y1, respectively. An analysis in terms of the ab initio density functional theory and the statistical adiabatic channel modelSACM.indicates that the formation of chlorine atoms by unimolecular decomposition of the initially formed C2ClF3SACM.indicates that the formation of chlorine atoms by unimolecular decomposition of the initially formed C2ClF3 or C2Cl2F2 energized adducts can be discarded at room temperature. Employing isodesmic reaction schemes at the B3LYPr6-311qqGd,p.level of theory, the enthalpy of formation of C2Cl2F2, C2ClF2 and C2F3 are calculated to be2Cl2F2 energized adducts can be discarded at room temperature. Employing isodesmic reaction schemes at the B3LYPr6-311qqGd,p.level of theory, the enthalpy of formation of C2Cl2F2, C2ClF2 and C2F3 are calculated to ber6-311qqGd,p.level of theory, the enthalpy of formation of C2Cl2F2, C2ClF2 and C2F3 are calculated to be y78.3"4, y18.1"4 and y59.9"4 kcal moly1, respectively.78.3"4, y18.1"4 and y59.9"4 kcal moly1, respectively.