Science and Technology Production
Article
Authorship
Date
2000
Publishing House and Editing Place
AMERICAN CHEMICAL SOCIETY
Magazine
JOURNAL OF PHYSICAL CHEMISTRY A,
vol. 104
(pp. 3117-3125)
AMERICAN CHEMICAL SOCIETY
Summary
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SIGEVA
The photolysis of Na2S2O8 aqueous solutions containing Cl- ions is a clean method for kinetic studies of the species Cl/ Cl2- 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 Cl2- (340 nm) radical ions in the presence and absence of benzene. A mechanism is proposed which accounts for the decay of Cl2- in aqueous solutions containing chloride ion concentratio...
The photolysis of Na2S2O8 aqueous solutions containing Cl- ions is a clean method for kinetic studies of the species Cl/ Cl2- 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 Cl2- (340 nm) radical ions in the presence and absence of benzene. A mechanism is proposed which accounts for the decay of Cl2- in aqueous solutions containing chloride ion concentrations in the range 1 × 10-4 to 0.6 M, total radical (Cl + Cl2-) concentrations in the range (0.1-1.5) × 10-5 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 × 109 M-1 s-1 k 1.2 × 1010 M-1 s-1 and < 1 × 105 M-1 s-1 were determined for the reactions of Cl and Cl2- 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 O2 and Cl-CHD. A reaction mechanism leading to the formation of chlorobenzene is proposed.
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