Kinetics of phenyl radical reactions with selected cycloalkanes and carbon tetrachloride

The kinetics of C₆H₅ reactions with c-C₅H₁₀, c-C₆H₁₂, c-C₇H₁₄, c-C₈H₁₆, and CCl₄ have been studied by means of the cavity-ring-down technique in the temperature range 297-523 K. The rates of these reactions were monitored by measuring either the decay of C₆H₅ at 504.8 nm or the formation of C₆H₅O₂ at 496.4 nm (or 510 nm) when a small, constant amount of O₂ was added to the slow-flowing reaction mixtures. Our absolute rate constants determined at several specific temperatures compare reasonably well with those measured in solution by either a direct probing (as for CCl₄) or an indirect, relative rate method (as for the cycloalkanes). The effects of temperature on the reactions with CCl₄, c-C₅H₁₀, and c-C₆H₁₂ have been investigated and our results give rise to the following Arrhenius equations: k_CCl4 = 10^-11.70±0.05±á°5 exp[(-1379 ± 56)/T]; k_c-c5H10 = 10^-11.35±0.08 exp[(-2039 ± 66)/T]; k_c-C6Hl2 = 10^-11.10±024 exp[(-1913 ± 191)/T], where k_x's are given in units of cm³/molecule·s. Our averaged value of k_CCl4 at 333 K, 3.40 × 10^-14 cm³/molecule·s, was used to evaluate many rate constants for C₆H₅ reactions with hydrocarbons (RH) of interest to combustion using previously determined k_RH/k_CCl4 ratios in solution.