Kinetic study of the reactions of chlorine atoms and Cl{sub 2}{sup .-} radical anions in aqueous solutions. 1. Reaction with benzene

Journal Article · Thu Apr 13 04:00:00 EDT 2000 · Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory

DOI:https://doi.org/10.1021/jp9929768· OSTI ID:20034403

Alegre, M L; Gerones, M; Rosso, J A; Bertolotti, S G; Braun, A M; Martire, D O; Gonzalez, M C

The photolysis of Na{sub 2}S{sub 2}O8 aqueous solutions containing Cl{sup {minus}} ions is a clean method for kinetic studies of the species Cl{sup {sm_bullet}}/Cl{sub 2}{sup {sm_bullet}{minus}} in the absence and presence of added aromatic substrates. Laser and conventional flash-photolysis techniques were employed to investigate the aqueous phase reactions of chlorine atoms and Cl{sub 2}{sup {sm_bullet}{minus}} (340 nm) radical ions in the presence and absence of benzene. A mechanism is proposed which accounts for the decay of Cl{sub 2}{sup {sm_bullet}{minus}} in aqueous solutions containing chloride ion concentrations in the range 1 x 10{sup {minus}4} to 0.6 M, total radical (Cl{sup {sm_bullet}} + Cl{sub 2}{sup {sm_bullet}{minus}}) concentrations in the range (0.1--1.5) x 10{sup {minus}5} M, and pH in the range 2.5--3.0. Interpretation of the experimental data is supported by kinetic computer simulations. The rate constants 6 x 10{sup 9} M{sup {minus}1} s{sup {minus}1} {le} {kappa} {le} 1.2 x 10{sup 10} M{sup {minus}1} s{sup {minus}1} and <1 x 10{sup 5} M{sup {minus}1} s{sup {minus}1} were determined for the reactions of Cl{sup {sm_bullet}} and Cl{sub 2}{sup {sm_bullet}{minus}} with benzene, respectively, in the aqueous phase. The organic radicals produced from these reactions exhibit an absorption band with maximum at 300 nm, which was assigned to a Cl-cyclohexadienyl radical (Cl-CHD). The kinetic analysis of the traces supports a reversible reaction between O{sub 2} and Cl-CHD. A reaction mechanism leading to the formation of chlorobenzene is proposed.

• Research Organization: Univ. Nacional de La Plata (AR)
• OSTI ID: 20034403
• Journal Information: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 14 Vol. 104; ISSN 1089-5639; ISSN JPCAFH
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC CHEMISTRY
BENZENE
CHEMICAL REACTION KINETICS
CHLORINE
CLOUDS
PHOTOLYSIS
RADICALS
TROPOSPHERE