REACTIONS OF ATOMIC OXYGEN (P-3) WITH SELECTED ALKANES

Rate constants for the reactions of atomic oxygen (P-3) With selected alkanes (C-2-C-6 Straight chain alkanes, C-C6H12, neo-C5H12, and i-C4H 10) have been determined directly by a laser photolysis-shock tube-ato mic resonance absorption method at high temperatures (850-1250 K). For n-C6H14 and c-C6H12, rate constants have been also determined at lowe r temperatures (296-400 K) by a laser photolysis-vacuum ultraviolet la ser-induced fluorescence method. Present results agree with the TST ca lculation by Cohen and Westberg [Int. J. Chem. Kinet. 1986, 18, 99] wi thin experimental error limits except for O + c-C6H12 and O + neo-C5H1 2. The group additivity of the rate constants for different C-H bonds (primary, secondary, and tertiary) is examined and neo-C5H12 and c-C6H 12 are found to be good representatives of primary and secondary C-H b onds, respectively, for C-4 and larger alkanes. A trial is made to inv estigate the J dependence of reactivity of atomic oxygen (P-3(J)) With c-C6H12 to examine the adiabatic correlation of reactants and product s. No evidence for such J dependence can be observed due to the rapid relaxation among the spin-orbit components. Rate constants for the int ratriplet relaxation processes are evaluated for He as a collision par tner.