The polarographic reduction of 4-nitro DPA in methanol-water mixtures of varying composition (30-80% v/v) in the pH range 1-12 was investigated. A single wave was observed in the reduction in these media at all pH values and solvent compositions. The number of electrons involved in the reduction was found to be six in all solutions indicating that 4-amino DPA is the final product. A mechanism consistent with these observations which involves the formation of 4-hydroxylaminodiphenylamine as an intermediate has been proposed. © 1978 Elsevier Sequoia S.A.

Chittoor Sivaramakrishnan Venkatachalam

Chatty Kalidas

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IIT Madras

Polarography of 4-nitrodiphenylamine (DPA) in methanol-water mixtures⋆

Journal of Electroanalytical Chemistry

2,2′-dinitrobenzidine (2,3′-DNB) gives a single diffusion-limited irreversible polarographic wave in buffered aqueous methanol. Microcoulometric experiments indicate a transfer of ten electrons in the reduction and cyclic voltammetric studies show direct proof for the existence of a nitroso intermediate. Based on the results obtained, a suitable mechanism is proposed for the reduction of 2,3′-DNB in buffered methanolic solutions. © 1989 Chapman and Hall Ltd.

Journal of Applied Electrochemistry

Electrochemical reduction of 2,3′-dinitrobenzidine in buffered aqueous methanol

The electroreduction of 2-nitrobenzidine (2-NB) in buffered methanol-water mixtures in the composition range 20-80% (v/v) and pH range 2.80-12.00 gave a single six-electron diffusion-controlled irreversible wave. On the basis of the results obtained, a diphenoquinone-diimine intermediate is suggested in the mechanism of 2-NB reduction in methanol-water mixtures. © 1986 Indian Academy of Sciences.

Proceedings of the Indian Academy of Sciences - Chemical Sciences

Electrochemical reduction of 2-nitrobenzidine in methanol-water mixtures

The electrochemical reduction of 2-nitrobenzidine (I) has been investigated in N,N-dimethylformamide solutions. Two well-defined polarographic waves in the ratio 1:3 were obtained. The first wave was found to be a reversible, diffusion-controlled, single electron wave while the second was the result of a diffusion-controlled, irreversible, three-electron process with chemical complications. The nitro and nitroso anion radical intermediates of I formed during the CPE experiments were detected by an ESR technique and confirmed later by cyclic voltammetry. The "current oscillations" observed in the cyclic voltammograms of I are discussed. An eece-type of sequence is suggested for I reduction leading to the formation of 2-hydroxylaminobenzidine. © 1984.

Electrochemical behaviour of 2-nitrobenzidine in N,N-dimethylformamide

The polarographic reduction of 2,4,6-trinitro diphenylamine was found to give three waves of nearly equal height in all pH regions in buffered solutions and also in unbuffered methanol-water mixtures. The waves were shown to be diffusion-controlled and irreversible on the basis of the usual criteria. Controlled-potential electrolysis at the limiting region of the third wave gave napp = 18 and thus it was shown that napp = 6 for each of the waves. It was concluded that each of the nitrogroups in the compound is reduced to the corresponding amino group, the nitro groups ortho to the NH group in the parent compound being reduced first followed by the other. Cyclic voltammetric experiments in unbuffered solutions gave evidence for a new redox system which was attributed to amine-quinone diimine intermediate couple. It was inferred that each of the nitro groups in the compound is reduced to the amino function via this intermediate. © 1981.

Electrochimica Acta

Electrochemical reduction of 2,4,6-trinitro diphenylamine in buffered and unbuffered methanolic solutions

Two six-electron diffusion-controlled irreversible waves are obtained for the polarographic reduction of 2,4-dinitrodiphenylamine (DPA) in buffered and unbuffered media in all compositions of methanol-water mixtures. Based on the polarographic and coulometric data, it is suggested that each of the nitro groups is reduced to the corresponding amine in a single step via the diimine intermediate to give 2,4-diamino DPA as the final product. The influence of various factors such as structure of the depolariser, pH and composition of methanol on the reduction of the compound is also discussed. © 1980 Indian Academy of Sciences.

Journal	Journal of Electroanalytical Chemistry
ISSN	00220728
Open Access	No