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in BRITISH COLUMBIA CHAPTER OF UNION PARTY OF CANADA by (47k points)
No supporting electrolyte was required for electrochemical catalysis in surfactant media experiments.These nonpolar compounds bind to surfactant <a href="http://www.targetmol.com/compound/Dyclonine-hydrochloride">Targetmol's Dyclonine hydrochloride</a> aggregates at the hydrophobic sites, thereby providing excellent substrates for rate enhancements.Catalytic reductions of aryl halides have been studied in micellar systems, aimed at enhancing reaction rates had earlier reported the electrolytic reduction of allyl chloride by tris in aqueous SDS and CTAB micelles.According to these researchers and others, a great deal remains to be understood about the fundamental and practical aspects of electrode reactions in microemulsions and micellar solutions. Use of cyanocobalamin as an electrocatalyst has been widely discussed as well.Anodic peak is also missing in direct reduction of dicofol.This also implies an irreversible electrode process.Hence, reversibility depends on the relative values of electron transfer rate constant. In addition, shift in the geometry of the coordination sphere which is characteristic of transition metal complexes may also explain irreversibility observed in the present case.The effect of SDS on the electrochemical behavior becomes evident by comparing the voltammograms in acetonitrilewater with the ones in SDS.There is a remarkable increase in cathodic peak current in SDS.Factors that change the composition of the electrode include passivating oxides and adsorbed species on the surface, which in turn influences the electron transfer.The nature of the electroactive species in the solution also critically affects the exchange current densities, both the reduced and oxidized form.Less important, but still relevant, are the environment of the solution including the solvent, nature of the electrolyte and temperature. The peak current enhancement increased with increase in scan rate.This can be   explained by the size of diffusion layer and the time taken to record the voltammogram.In slow voltage scan, the diffusion layer grows much further from the electrode in comparison to a fast scan rate.Consequently, the flux to the electrode surface is small at slow scan rate than it is at fast scan rates.Since the current is proportional to the flux towards the electrode, the magnitude will be lower at low scan rates and higher at high scan rates.It is worth noting that the concentrations for dicofol and cyanocobalamin are the same as those used in acetonitrilewater.Hence, the peak current enhancement and the slight shift in peak potentials are not as a result of concentration changes.This could be explained further by the fact that surfactants can assemble in the bulk solution into aggregates. The micellar solution brings together the ionic and nonpolar reactants in close proximity, consequently amplifying the analytical sensitivity.It is likely that the catalyst and the substrate have been encapsulated within the same region of the micelle, thus increasing their concentration and interaction at the surface of the electrode.This implies that electrocatalyis is not diffusion controlled.The current efficiency in SDS decreased with increase in scan rate, as expected. This is due to the decrease in the time the catalyst and the substrate interact on the surface of the electrode.Figure: A plot of cathodic peak current versus x M square root of scan rate for cyanocobalamin in SDS.This makes electrocatalytic reduction more thermodynamically favourable in surfactant media than in organic solvents.

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