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Polarographic and electrochemical studies of some aromatic and heterocyclic nitro compounds, part IV: Polarographic reduction of 2‐alkylnitroimidazoles and aminonitroimidazoles
Author(s) -
Dumanović D.,
Jovanović J.,
Sužnjević D.,
Erceg M.,
Zuman P.
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.1140040909
Subject(s) - chemistry , polarography , nitro , alkyl , hydroxylamine , medicinal chemistry , amine gas treating , nitro compound , aromatic amine , catalysis , inorganic chemistry , organic chemistry
1, 2‐Dialkyl‐4‐nitroimidazoles are reduced between pH 0 and 13 in a four‐electron wave. The resulting arylhydroxylamine is stable and in acidic media reduced further to the amine. 1,2‐Dialkyl‐5‐nitroimidazoles and 2‐alkyl‐4(5)‐nitroimidazoles are reduced in alkaline media with the number of electrons approaching six. The hydroxylamine derivative formed in these reductions can be dehydrated and yields an easily reducible, quinone‐like ketimine. The rate of the dehydration governs the heights of the first step and is base catalyzed. The sequence of electron and proton transfers for 2‐ alkylsubstituted nitroimidazoles is the same as that observed for corresponding desalkyl compounds. 1‐Alkyl‐4‐amino‐5‐nitroimidazoles, as well as 1‐alkyl‐4‐nitro‐5‐aminoimidazoles, are reduced in a single wave, the height of which approaches that of a six‐electron process. The dehydration of the hydroxylamino derivative is favored, probably due to an internal base catalysis. The shifts of half‐wave potentials with pH differ principally from those of all other nitroimidazoles and indicate the predominant role of the amino group in the proton transfer.