LASER FLASH-PHOTOLYSIS OF PYRIDINE N-OXIDE - KINETIC-STUDIES OF ATOMIC OXYGEN [O(P-3)] IN SOLUTION

Laser flash photolysis of pyridine N-oxide in acetonitrile yields atom ic oxygen, O(P-3), in modest quantum yield. The reactivity of O(P-3) c ould be probed by monitoring the product of its reaction with the solv ent, assigned to acetonitrile oxide (CH3CNO). For example, reactions w ith dioxygen, 1-octene, and cyclopentane take place with rate constant s of 4.1 x 10(9), 8.7 x 10(9), and 3.8 x 10(8) M(-1) s(-1), respective ly, at room temperature. Isotope effects are ca. 6 for cyclohexane, wh ere H abstraction is responsible for the reaction, but negligible for benzene, acetonitrile, and pyridine, where addition reactions are beli eved to dominate. This is the first report of an extensive set of rate constants for the reactions of O(P-3) with a variety of organic and i norganic substrates in solution.