A Study of V (Ⅲ) - V(Ⅳ) and Ti(Ⅲ) - Ti(Ⅳ) Isotopic Exchange Reactions in Acid Solutions

摘要

The rate of exchange of radioactive 46V "between V(III) and V(IV) has been measured in aqueous acidic solutions containing various legends in¬cluding perchlorate, fluoride, chloride, bromide, iodide, sulfate, phos¬phate, oxalate, ethylene glycol, glyoxal, acetate, glycolate, gyloxalate, malonate, maleate, fumarate, and succinate. The V(IV) was separated from the V(III) by elution from cation-exchange resin columns with 2 M HClO4. Each of the ligands catalyzes the exchange except chloride (≤ 3-8 M), bromide (≤ 1 M), iodide (≤ 1 M), ethylene glycol and glyoxal. In per¬chloric acid, the exchange rate increases with increasing ionic strength in accord with the extended form of the Bronsted-Bjerrum equation, and the rate decreases twofold when heavy water is substituted for ordinary water. When the reaction mixtures contain sulfuric acid, however, the deuterium dependence vanishes. In the presence of sulfuric acid, hydro¬fluoric acid or oxalic acid the V(III) - V(IV) exchange has been found to obey the rate laws;