Some simple, highly reactive, inorganic chlorine derivatives in aqueous solution. Their formation using pulses of radiation and their role in the mechanism of the Fricke dosimeter

Abstract

In aqueous solution OH radicals react with chloride ions to form initially ClOH-, the rate constant being 4.3 k 0 . 4 ~ lo9 1. mol-' s-'. The rate constant for the dissociation of ClOH-back to OH radicals and chloride ions is 6.1 k0.8 x lo9 s-I. ClOH-is converted to chlorine atoms via the reaction, C10H-+H++C1+H20 (k = 2.1 k 0.7 x 10'O 1. mol-' s-' at an ionic strength of unity), the rate constant for the reverse reaction being 1.3 x lo3 1. mol-' s-' (0.3-3.0 x lo3 1. mol-' s-').Chlorine atoms combine with chloride ions to form Cl, (k = 2.1 x 1O'O 1. mo1-' s-I), the rate constant for the dissociation of Cl, back to chlorine atoms and chloride ions being 1.1 k 0.4 x lo5 s-'.Cl, absorption has a maximum at 340 nm where the extinction coefficient is 8.8 t-0.5 x lo3 1. mol-' cm-', whereas ClOH-has a maximum at 350 nm with an extinction coefficient of 3.7k0.4 x lo3 1. mol-' cm-l. The reactions of chlorine atoms and Cl, with ferrous ions have also been investigated and the constants are 5.9k0.6 x lo9 and 1.4k0.2 x lo7 1. mol-' s-' (ionic strength = 0.1 moll.-') respectively. The effect of chloride ions on the mechanism of the Fricke dosimeter is discussed.The absorption spectra of ClOH-and Cl, have been measured in the range 230-450 nm.

Mécanisme des réactions du chlorite et du dioxyde de chlore. 3. La dismutation du chlorite

“…L'interprktation de sa diminution avant le minimum donnee par ces auteurs ne peut Ctre retenue car elle fait intervenir la rCaction HClO + C1-+ H+ -+ C1, + H20 en exigeant qu'elle soit irreversible dans ces conditions, ce qui est exclu (1 1). Dans le cadre de notre mkcanisme cette diminution peut s'expliquer simplement par la rkaction C1 + C1-G C12 (12). Si C1, disparait plut6t par une reaction de rupture que par une rkaction analogue a [12], les ions C1-diminuent la vitesse de la decomposition en chaine de HC102.…”

Production of gas phase NO2 and halogens from the photolysis of thin water films containing nitrate, chloride and bromide ions at room temperature

“…[33][34][35][36][37] The OH radical formed from the O À reaction 58 with H 2 O oxidizes Br À and Cl À to form Br 2 , Cl 2 and BrCl. 30,[59][60][61][62][63][64][65][66][67][68][69][70][71] These reactive halogen gases play a significant role in the chemistry and composition of the marine boundary layer (MBL). 45,[72][73][74][75][76][77][78][79][80][81] In the coastal MBL, the photochemical cycling of chlorine enhances tropospheric ozone, whereas gaseous bromine species cause ozone destruction during polar sunrise in polar regions 75,76,[82][83][84][85] as well as in midlatitudes.…”

Free radical production requires both inducible nitric oxide synthase and xanthine oxidase in LPS-treated skin

“…Although allopurinol reacts with hydroxyl radical at the near diffusion-limited rate of Ϸ10 9 M Ϫ1 ⅐s Ϫ1 (25), this very high rate is typical for reactions of the hydroxyl radical that reacts with chloride ion at the rate of 4.3 ϫ 10 9 M Ϫ1 ⅐s Ϫ1 (26) and with GSH at the rate of 1.3 ϫ 10 10 M Ϫ1 ⅐s Ϫ1 (27). Because both of these compounds as well as many other biochemicals react with the hydroxyl radical at near diffusion-limited rates, reactions of hydroxyl radical with allopurinol will be a very, very small fraction of the total reactions of the hydroxyl radical in vivo; therefore, hydroxyl radical scavenging by allopurinol cannot be the explanation of the effects we observed (Figs.…”