Detection of the short-lived cation radical intermediate in the electrochemical oxidation of N,N-dimethylaniline by scanning electrochemical microscopy.
J Am Chem Soc
; 136(52): 18163-9, 2014 Dec 31.
Article
em En
| MEDLINE
| ID: mdl-25478724
ABSTRACT
The short-lived intermediate N,N-dimethylaniline (DMA) cation radical, DMA(â¢+), was detected during the oxidation of DMA in MeCN with 0.1 M tetra-n-butylammonium hexafluorophosphate. The detection was accomplished at steady state by scanning electrochemical microscopy (SECM) with ultramicroelectrodes using the tip generation/substrate collection mode. Cyclic voltammetry (CV) with a 2 mm Pt electrode indicates that DMA oxidation in acetonitrile is followed by a dimerization and two electrochemical reactions, which is consistent with previous results. The DMA(â¢+) intermediate is detected by SECM, where the DMA(â¢+) generated at the ca. 500 nm radius Pt tip is collected on a 5 µm radius Pt substrate when the gap between the tip and the substrate is a few hundred nanometers. Almost all of the DMA(â¢+) is reduced at the substrate when the gap is 200 nm or less, yielding a dimerization rate constant of 2.5 × 10(8) M(-1)·s(-1) based on a simulation. This is roughly 3 orders of magnitude larger than the value estimated by fast-scan CV. We attribute this discrepancy to the effects of double-layer capacitance charging and adsorbed species in the high scan rate CV.
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01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2014
Tipo de documento:
Article