Kinetics of the Reactions of O.- and HO.- with aaatrifluorotoluene and 4-Fluorotoluene.

L.S. VILLATA; J.A. ROSSO; M.C. GONZALEZ; D.O.MÁRTIRE

JOURNAL OF CHEMICAL RESEARCH-S

SCIENCE REVIEWS 2000 LTD

Año: 1997 p. 172 - 173

0308-2342

The photolysis of strong alkaline solutions (pHa12.7) ofhydrogen peroxide (pKa=11.61) yields HO./O.µ radicals(pKa211.9) [eqns. (1) and (µ1) in Table 1]. In the presenceof molecular oxygen, O.µ radicals reversibly react with O2yielding ozonide radical ions, O3.µ [eqns. (2) and (3)] .2–4Ozonide itself is thought to be rather unreactive towardsnon-radical substrates; however its decay rate is extremelysensitive to small quantities of HO./O.µ scavengers.5–7 In previousinvestigations4 it has been shown that in solutions containingH2O2 concentrations of the order of 5Å10µ5 moldmµ3 or larger and added substrates (S), competitionbetween H2O2, S and O2 for O.µ/HO. radicals rules the formationefficiency and decay rate of O3.µ. A detailed kineticstudy on the O3.µ concentration profiles following flashphotolysis of alkaline hydrogen peroxide solutions in thepresence of scavengers yields kinetic information on the reactionsbetween O.µ/HO. and the substrates [eqns. (6) and(7)].4 Based on this methodology, we report here a kineticstudy of the reactions of O.µ/HO. radicals with a,a,a-trifluorotoluene(TFT) and 4-fluorotoluene (4-FT).