The kinetics and mechanisms of the copper (II) - catalyzed iron (III) - sulfur (IV) reaction in a chloride medium



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Texas Tech University


The object of the work reported in this dissertation is the mechanistic study of the oxidation of sulfur(IV) in acidic aqueous solutions. Iron(III) perchlorate was used as the oxidant, but the reaction was carried out in a chloride medium. Thus, the dominant iron(III) species was a monochloroiron(III) complex even though iron(III) was originally added as the perchlorate salt. The term, iron (III), is used to designate the reactive iron complex where the iron is in the +3 oxidation state. The reaction was found to be catalyzed by copper(II). Copper(II)- catalyzed reactions of hydrated iron(III) and sulfur(IV) have been previously studied, ' as have uncatalyzed reactions of iron(III) and sulfur(IV).2'^"1^ The possible products of the reaction are sulfate and dithionate ions. Under most conditions, both reactions 1 and 2 occur to give a mixture of dithionate and sulfate in solutions containing no catalysts.