Title: Viologen
Literature References: A term coined by Michaelis to designate the chlorides of certain quaternary bases derived from g,g¢-dipyridyl. Presently used as dichlorides, dibromides and diiodides. Prepn: Michaelis, Biochem. Z. 250, 564 (1932); Michaelis, Hill, J. Am. Chem. Soc. 55, 1481 (1933); J. Gen. Physiol. 16, 859-873 (1933). Viologens are useful as oxidation-reduction indicators because their potential range is very negative. In contrast to other redox indicators, the color is exhibited by the reduced form, whereas usually the oxidized form is the colored one and secondly, the redox potential of these substances is independent of pH. Review of electrochemistry: C. L. Bird, A. T. Kuhn, Chem. Soc. Rev. 10, 49-82 (1981).
Derivative Type: Ethyl viologen
Additional Names: 1,1¢-Diethyl-4,4¢-bipyridinium; N,N¢-diethyl-g,g¢-dipyridylium
Properties: Normal potential at 30°: -0.449 volts.
Derivative Type: Benzyl viologen
Additional Names: 1,1¢-Bis(phenylmethyl)-4,4¢-bipyridinium; N,N¢-dibenzyl-g,g¢-dipyridylium
Properties: Normal potential at 30°: -0.359 volts.
Derivative Type: Betaine viologen
Additional Names: N,N¢-Dibetaine-g,g¢-dipyridylium
Properties: Normal potential at 30°: -0.444 volts.
Derivative Type: Dimethyl analog see Paraquat
Use: As biological oxidation-reduction indicators. |