Radiation-induced dechlorination of pentachloroethane and sym-tetrachloroethane. Reactions of 1,1,2,2-tetrachloroethyl and 1,2,2-trichloroethyl radicals

Abstract

Pentachloroethyl 1,1,2,2-tetrachloroethyl and 1,1,2-trichloroethyl radicals were produced by the reactions of radiolytically generated cyclohexyl radicals with pentachloroethane and sym-tetrachloroethane. The kinetics of the following reactions were studied: c-C₆H₁₁+ C₂Cl₅H →c-C₆H₁₁Cl + C₂Cl₄H (2), c-C₆H₁₁+ C₂Cl₅H →c-C₆H₁₂+ C₂Cl₅(3), C₂Cl₄H + c-C₆H₁₂→C₂Cl₄H₂+ c-C₆H₁₁(4), C₂Cl₄H →C₂Cl₃H + Cl (5), c-C₆H₁₁+ C₂Cl₄H₂→c-C₆H₁₁Cl + C₂Cl₃H₂(11), c-C₆H₁₁+ C₂Cl₄H₂→c-C₆H₁₂+ C₂Cl₄H (12), C₂Cl₃H₂+ c-C₆H₁₂→C₂Cl₃H₃+ c-C₆H₁₁(13), C₂Cl₃H₂→C₂Cl₂H₂+ Cl. (14). The following rate expressions were obtained: log₁₀(k₂/k₃)= 1.40±0.15 –(660±230)/4.576T; log₁₀(k₁₁/k₁₂)= 1.07±0.06 –(3780±120)/4.576T: log₁₀(k₅/k₄)(mol l.^–1)= 5.63±0.07 –(8100±100)/4.576T; log₁₀(k₁₄/k₁₃)(mol l.^–1)= 5.91±0.21 –(6900±400)/4.576T. R the gas constant was taken to be 1.9872 cal K^–1mol^–1 and subsequent activation energies expressed in cal mol^–1(1 cal = 4.1855 J).