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Presents technique for microscopic imaging of electrochemically active surfaces. Theoretical spatial resolutions of the scanning capillary microscopy/mass spectrometry; Electrochemistry of dimethyl-p-phenylenediamine (DPD); Flow characteristics in the flow cell scanner; Mass spectrometric monitoring of DPD and its oxidation products during potential scan.

The relationship between homogeneouscatalysis and electrochemistry is examined in light of two examplesbased on our work concerning (a) catalyst activation, regarding selectiveelectrochemical C–H oxidation with RuIII/RuIVmediation, and (b) catalyst suppression, regarding controllingselectivity in electrochemical aromatic chlorination. The first example(a) deals with the role of catalysis at the working electrode. Theelectrochemical (EC) oxidation of specific hydrocarbons such as tetralinand indane is performed using tris(acetonitrile)ruthenium trichloride(Ru(CH3CN)3Cl3) as a mediator. Therole of this mediator in the oxidation of tetralin has been reported.This homogeneous C–H activation by electron transfer (ET) isaccompanied by the redox transitions of the mediator in the courseof the catalytic oxidation, and these are the main points of interesthere. Additional studies with a rotating ring disk electrode (RRDE)provided a follow-up of creation and recovery of RuIII/RuIIand RuIII/RuIVspecies in the process.Using electrochemistry linked with electrospray ionization mass spectrometry(EC/ESI-MS) gave additional information on the structure of the reducedand oxidized forms of Ru(CH3CN)3Cl3and the effect of water in the solvent on their lifetimes. The secondexample (b) of electrochlorination has been reported elsewhere andis brought up as complementary remarks. Aromatic electrophilic chlorinationof 1,4-dimethoxy-2-tertbutylbenzene is autocatalyzed and unselective.The EC procedure provides a simple means to inhibit the catalyticrunaway reaction. This example shows how the counter electrode affectscatalysis and selectivity. [ABSTRACT FROM AUTHOR]