Oxidative dimerization of 4-nitrophenolate

In an EC2j process, the initial ET step is followed by a second-order irreversible homogeneous reaction. For example, the feedback mode of SECM was employed to study the reductive hydrodimerization of the dimethyl fumarate (DF) radical anion [22]. The experiments were carried out in solutions containing either 5.15 or 11.5 mM DF and 0.1 M tetrabutylammonium tetrafluoroborate in A,A,-dimethyl form amide (DMF). The increase in the feedback current with increasing concentration of DF indicated that the homogeneous step involved in this process is not a first-order reaction. The analysis of the data based on the EC2 theory yielded the fc2 values of 180M-1 s-1 and 160M-1 s-1 for two different concentrations. Another second order reaction studied by the TG/SC mode was oxidative dimerization of 4-nitrophenolate (ArO-) in acetonitrile [23]. In this experiment, the tip was placed at a fixed distance from the substrate. The d value was determined from the positive feedback current of benzoquinone, which did not interfere with the reaction of interest. The dimerization rate constant of (1.2 0.3) x 108 M x s-1 was obtained for different concentrations of ArO-. 

The rate constant for the rapid oxidative dimerization of 4-nitrophenolate (ArO ) in acetonitrile solutions has been measured using the TG/SC mode (5), in which the following processes occurred ... 

FIGURE 5.12 Kinetic parameter k as a function of the collection efficiency ( /s//x )- (A) E Cj mechanism K=k tPlD, solid line was computed from Equation 5.85, diamonds are simulated data taken from Ref. [5]. (B) EjCji mechanism k =c° k tP/aD, solid line was computed from Equation 5.88, squares are simulated data taken from Ref. [54]. (Reprinted with permission from Treichel, D.A., Mirkin, M.V., and Bard, A. J., Scanning electrochemical microscopy. 27. Application of a simplified treatment of an irreversible homogeneous reaction following electron transfer to the oxidative dimerization of 4-nitrophenolate in acetonitrile, J. Phys. Chem., 98, 5751-5757, 1994. Copyright 1994 American Chemical Society.)... 

Treichel, D. A., Mirkin, M. V., Bard, A. J. 1994. Scanning electrochemical microscopy. 27. Application of a simplified treatment of an irreversible homogeneous reaction following electron transfer to the oxidative dimerization of 4-nitrophenolate in acetonitrile. J Phys Chem 98 5751-5757. 

The metabolism of an oral dose of 50-100 mg/kg "C-1,3-DNB was followed in rabbits (Parke 1961). Of the metabolites detected in urine, 30% were conjugated with glucuronic acid and 6% with sulfate. The major urinary metabolites of 1,3-DNB were 2,4-diaminophenol (31%), 1,3-phenylenediamine (25%), 1,3-nitroaniline (18%), and 2-amino-4-nitrophenol (14%). Other minor metabolites comprising about 20% of the label were oxidation and reduction products and azoxy dimers. 

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