title: Kinetics and mechanisms of aqueous ozone reactions with bromide, sulfite, hydrogen sulfite, iodide, and nitrite ions.
abstract: Reactions of ozone with Br(-), SO(3)(2-), HSO(3)(-), I(-), and NO(2)(-), studied by stopped-flow and pulsed-accelerated-flow techniques, are first order in the concentration of O(3)(aq) and first order in the concentration of each anion. The rate constants increase by a factor of 5 x 10(6) as the nucleophilicities of the anions increase from Br(-) to SO(3)(2-). Ozone adducts with the nucleophiles are proposed as steady-state intermediates prior to oxygen atom transfer with release of O(2). Ab initio calculations show possible structures for the intermediates. The reaction between Br(-) and O(3) is accelerated by H(+) but exhibits a kinetic saturation effect as the acidity increases. The kinetics indicate formation of BrOOO(-) as a steady-state intermediate with an acid-assisted step to give BrOH and O(2). Temperature dependencies of the reactions of Br(-) and HSO(3)(-) with O(3) in acidic solutions are determined from 1 to 25 degrees C. These kinetics are important in studies of annual ozone depletion in the Arctic troposphere at polar sunrise.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: L M
authors.initials: LM
authors.lastname: Schurter
authors.forename: C E
authors.initials: CE
authors.lastname: Muller
authors.forename: S
authors.initials: S
authors.lastname: Aloisio
authors.forename: J S
authors.initials: JS
authors.lastname: Francisco
authors.forename: D W
authors.initials: DW
authors.lastname: Margerum