126901-00-6Relevant academic research and scientific papers
Non-metal redox kinetics: Reactions of iodine and triiodide with sulfite and hydrogen sulfite and the hydrolysis of iodosulfate
Yiin, Boudin S.,Margerum, Dale W.
, p. 1559 - 1564 (2008/10/08)
The reactions of I3- and I2 with SO3H- and SO32- (in the p[H+] range 4.1-6.6) are studied by the pulsed-accelerated-flow technique. Pseudo-first-order rate constants (excess [SO32-]T and [I-]) are measured in the range from 6300 to 74000 s-1 (25.0°C, μ = 0.50). The proposed mechanism is I3- + SO3H- →k1 ISO3- + 2I- + H+ I2 + SO3H- →k2 ISO3- + I- + H+ I3- + SO32- →k3 ISO3- + 2I- I2 + SO32- →k4 ISO3- + I- where the second-order rate constants (M-1 s-1) are k1 = 1.5 × 107, k2 = 1.7 × 109, k3 = 2.9 × 108, and k4 = 3.1 × 109. The iodosulfate that is formed hydrolyzes with a first-order rate constant of 298 s-1 at 25.0°C. ISO3- + H2O →kh I- + SO42- + 2H+ A temperature-dependent stopped-flow study gives ΔH≠ = 65 kJ mol-1 and ΔS≠ = 21 J mol-1 K-1 for the hydrolysis reaction. The positive ΔS≠ value indicates a dissociative mechanism without the addition of H2O in the transition state for ISO3- hydrolysis.
