The reaction between thallium(III) and hydrogen peroxide

Abstract

The reaction between Tl^III and H₂O₂ has been followed by ethylenediaminetetra-acetate titration and iodimetrically, and the rate law is as in (i). The rate is independent of ionic strength (0.5–3.0 mol dm^–3 Na[ClO₄])–d[Tl^III]//_dt=[Tl^III][H₂O₂]²(k₂//_[H⁺]+k₃[H₂O₂]//_[H⁺]²)(i) and the presence of thallium(I) ions, but is inhibited by addition of sulphate and chloride ions as well as monomers and radical scavengers. From the temperature dependence (5–25 °C) of the apparent rate constants the apparent activation energy is 27.0 ± 0.5 kcal mol^–1 for k₂ and 28.2 ± 0.5 kcal mol^–1 for k₃. The mechanism is explained (at least partly) by one-electron reactions of mono- and di-(hydrogenperoxo)thallium(III) species with H₂O₂.