Electro-Oxidation of Phenylenediamines and Related Compounds at Platinum Electrodes. Effects of Acid Strength.

Characterization of an amperometric laccase electrode covalently immobilized on platinum surface

“…The electrochemical oxidations of the isomers of PPD and related compounds have been extensively investigated [46] in non-aqueous and buffered aqueous systems. In acetonitrile, PPD shows two anodic waves at +0.24 and +0.85 V (vs. SCE) and the first wave corresponds to one-electron oxidation process to form a cation radical, PPD þÅ [47,48].…”

On-line electrochemical–mass spectrometry study of the mechanism of oxidation of N,N-dimethyl-p-phenylenediamine in aqueous electrolytes

“…Chemical oxidation of pphenylenediamines is well researched due to its application in color photography and hair coloring [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Information on the electrochemical oxidation of p-phenylenediamines is more limited [31][32][33][34][35][36][37][38][39][40][41]. Electrochemical oxidation of p-phenylenediamines in aqueous electrolytes is a 2-electron process generating quinonediimine (II) [32][33][34][35][36][37], reaction (a) in Scheme 1.…”

“…Information on the electrochemical oxidation of p-phenylenediamines is more limited [31][32][33][34][35][36][37][38][39][40][41]. Electrochemical oxidation of p-phenylenediamines in aqueous electrolytes is a 2-electron process generating quinonediimine (II) [32][33][34][35][36][37], reaction (a) in Scheme 1. In acidic electrolytes two single electron stages of oxidation were proposed for formation of quinonediimine [19,37,40].…”

Electrode Reactions of Aromatic Compounds in Strong Acid Solutions. Chronopotentiometric and Spectrometric Studies of the p-Hydroquinone-H2SO4 System at Platinum Electrodes.

“…A recent study of the anodic oxidation of phenylenediamine compounds (29) as a function acid strength of the supporting electrolyte showed that total protonation of the basic amine groups had a very large effect on the oxidation potential. Protonation of just one amino group (one free amino group remains) had no observable effect on the T h i s c o n t e n t i s quarter wave potential, Em, but total protonation (no free pair of electrons) shifted the Em about 250 mv.…”