15181-48-3Relevant articles and documents
Non-metal redox kinetics: Reactions of sulfite with dichloramines and trichloramine
Yiin, Boudin S.,Margerum, Dale W.
, p. 1942 - 1948 (2008/10/08)
Pulsed-accelerated-flow (PAF) and stopped-flow techniques are used to study the kinetics of HNCl2 and CH3NCl2 reactions with sulfite. Pseudo-first-order rate constants with excess sulfite at p[H+] 3.7-6.4 are measured from 35-45000 s-1 (25.0°C, μ = 0.50). Acid suppresses the rate because SO3H- is much less reactive than SO32-. The rate expression is -d[RNCl2]/dt = k1[RNCl2][SO32-], where k1 (M-1 s-1) is 5.8 × 106 for HNCl2 and 2.4 × 107 for CH3NCl2. The initial nitrogen product is RNHCl, which reacts further with sulfite. Trichloramine reactions with sulfite are measured by the PAF method under second-order conditions with unequal concentrations (25.0°C, μ = 0.50) from p[H+] 3.8 to 4.6. The rate expression is -d[NCl3]/dt = (k1[SO32-] + k2[SO3H-])[NCl3], where k1 is 4.5 × 109 M-1 s-1 and k2 is 1.4 × 107 M-1 s-1. The initial nitrogen product is HNCl2, which reacts further with sulfite. A Cl+-transfer mechanism is proposed for all the reactions with sulfite to give ClSO3- as an initial product that hydrolyzes to give Cl- and SO42-. The relative reactivities of active chlorine species with SO32- are NCl3 ? HNCl2 ? NH2Cl ? OCl-, where the NCl3 and HNCl2 reactions are suppressed by acid whereas the NH2Cl and OCl- reactions are acid assisted.
