Voltammetry without background electrolyte: Redox pattern of DPPH in non-aqueous media
✍ Scribed by D.A. Hall; P.J. Elving
- Publisher
- Elsevier Science
- Year
- 1967
- Tongue
- English
- Weight
- 887 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
Ab&aet-The voltammetric behaviour of dipheny&icrylhydraxyl (DPPH), a stable organic frre radical, which has been found to give reversible oxidation and reduction waves at latinum in O-1 M NaClO, solution in acetonitrile, was invest&ted at platinum and graphite electr J es in several media under a variety of conditions. The reported acetonltrile data were contirmed; comparison with data obtained in acetonitrile in the absence of background electrolyte has shown that voltammetry in such absence is quite feasible when using a three-electro& IR compensation circuit.
Variation of polarization rate, (0.1 M NaClO,; 0.1 M (CJ&NClG,), indicating electrode (platinum; oation direction, electrode rotation rate, background electrolyte .lyrolytic jg.aph-1 ad solvent (acetonitrile; pyridine; sulphur dioxide) revealed, ia, semi-reversi le behaviour of DPPH dependent on the presence of background electrolyte, adsorption of the neutral organic free radical on pyrolytic graphite, and a lack of stability for the compound in normally available reagent grade pyruline and in liquid sulphur dioxide (one product in both cases was diphenylpicrylhydraxine). The stability of DPPH in pyridine increased with purity of the solvent, which is of signifkance in connexion with the postulation of free radical intermediates in organic electrode processes.