Resumo

CABALLERO, N. B.; CROCE, A. E.  e  COBOS, C. J.. ESTUDIO CINÉTICO DE LA REACCIÓN CF₂ + CF₂ + He ?C₂F₄ + He A 296 K. Rep. cient. FACEN [online]. 2010, vol.1, n.1, pp.03-09. ISSN 2222-145X.

The laser flash photolysis-absorption technique has been used to study the CF₂ + He ? C₂F₄ + He, CFCl + CFCl + He ?CFClCFCl + He and CF₂ + CFCl + He ? CF₂CFCl + He recombination reactions at 296±2 K. The latest two reactions were found to be essentially at the second-order regime from 5 mbar up to 780 mbar of mixtures of CF₂CFCl/He. The derived limiting high-pressure rate coefficients are (3,7 ± 0,6) x 10^-14, (1,4 ± 0,5) x 10^-12 y (7,7 ± 0,3) x 10^-13 cm³ molecule^-1 s^-1, respectively. An analysis in of the transition steady state (TST), statistical adiabatic channel model/classic trajectory (SACM/CT) indicates that the formation of chlorine atoms initially formed like a primary photoproduct of CF2CFCl is possible. The thermochemistry of relevant molecular species via isodesmic reaction schemes with total energies computed at the B3LY/6-311++G (d, p) level of the density funtional theory. In this way, heat of formation values at 298 K of -78,3± 4, -59,9± 4 and 127,9± 4 kcal mol^-1 were respectively obtained for CFClCFCl, CF₂CF and CF₂ClCFCl molecules.

Palavras-chave : Chemical kinetics; Laser flash photolysis; Rate coefficients; Enthalpies of formation; CF₂; CFCl; CF₂CFCl; CFClCFCl.

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