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Polarographic and electrochemical studies of some aromatic and heterocyclic nitro compounds, part I: General mechanistic aspects
Author(s) -
Zuman Petr,
Fijalek Zbigniew,
Dumanovic Dragica,
Sužnjević Desanka
Publication year - 1992
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140040808
Subject(s) - chemistry , polarography , nitro , protonation , electrochemistry , electrolysis , dehydration , redox , quinone , medicinal chemistry , limiting , stereochemistry , inorganic chemistry , organic chemistry , electrode , ion , electrolyte , alkyl , mechanical engineering , biochemistry , engineering
Comparing reduction potentials of aromatic nitro compounds with those of corresponding nitroso compounds, by studying shifts of half‐wave and peak potentials with pH and by following the decrease of limiting current in buffered 35% DMF‐water mixtures, the sequence of protons and electrons in the four‐electron reduction step was proved to be: H + , e, H + , e, 2e, 2H + . Arylhydroxylamines formed in the four‐electron reduction of nitro compounds can be protonated and further reduced, they can undergo dehydration (provided that the dehydration product is stable), they can undergo chemical reactions with intermediates of the reduction of the nitro group, like ArNO \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\mathop 2\limits^.} $\end{document} , they can be electrooxidized to nitrosobenzenes (which can undergo chemical reactions) or they can react with carbonyl groups when present. Stabilization of the dehydrated form can occur in quinonemethide (nifedipine) or in some quinone‐like heterocyclic derivatives. Side reactions of ArNHOH and ArNO are demonstrated by smaller peaks in CV and by controlled potential electrolysis. Reactions of ArNHOH with carbonyl groups were observed by formation of new waves of nitrones in the reduction of nitrobenzenaldehydes.