A Rate - Catalyzed Reversible Reduction Of Sb(III) at the D.M.E. Induced by Trace Thiosulfate in HCLO4: A Comparison with Bromide

Alternating current polarography was employed to compare qualitatively the rate-enhancing properties of several electronically polarizable anions (including the halides) on the irreversible reduction of Sb(III) in HCLO 4 .In terms of the concentration required to produce one-half the maximum a.c. peak current for the reversible process it was found that added Na 2 S 2 0 3 in 0.75M HCLO 4 surpassed the halides by several orders of magnitude and that only micromolar levels of Na 2 S 2 0 3 are required to yield sharp, undistorted a.c. polarographic peaks and nernstian d.c. waves at −0.109 volt vs S.C.E. Millimolar levels of NaBr on the other hand were required to produce peaks of comparable height at −0.104 volt vs. S.C.E.