RESUMO
The electrochemical oxidation of tris(4-bromophenyl)amine in the presence of 2,6-lutidine is examined in acetonitrile. Voltammetric and spectroscopic investigations suggest that the electrogenerated triaryl aminium radical cation oxidizes 2,6-lutidine in an EC' mechanism, and an equilibrium constant for this homogeneous electron transfer is estimated. The mediated oxidation of a protected phenyl selenoglycoside by this reaction mixture is studied by the use of electrochemical ESR, employing a tubular flow cell, and signal intensity data is found to be consistent with the proposed mechanism, allowing the determination of kinetic parameters by computational simulation. Products of the mediated glycoside oxidation are determined by proton NMR and mass spectrometry.
Assuntos
Acetonitrilas/química , Compostos Organometálicos/química , Compostos de Amônio Quaternário/química , Eletroquímica , Eletrodos , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Estrutura Molecular , Oxirredução , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta/métodosRESUMO
A new approach to the measurement of objects with dimensions in the micron scale is proposed exploiting the spatial sensitivity of electrochemical measurements.
RESUMO
The size of a glass sphere positioned in the center of a microdisk electrode is determined by using a simple electrochemical procedure and is confirmed, additionally, by a microscopical measurement of the sphere at the time of the electrochemical measurement. The cyclic voltammetric response of the naked electrode and of the electrode with the sphere positioned in its center is recorded over a wide range of scan rates (0.002-1.5 V s(-1)). The size of the sphere is then determined by comparison of the experimental voltammogram with simulations for each individual scan rate.