Collect. Czech. Chem. Commun. 1985, 50, 1594-1601

Stability of radical anions derived from substituted 5-nitrofurans investigated by ESR spectroscopy

Jiří Klímaa, Larisa Baumaneb, Janis Stradinšb, Jiří Volkea and Romualds Gavarsb

a The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 118 40 Prague 1, Czechoslovakia
b Institute of Organic Synthesis, Latvian Academy of Sciences, Riga 6, Latvian SSR, U.S.S.R.


It has been found that the decay in dimethylformamide and dimethylformamide-water mixtures of radical anions in five of the investigated 5-nitrofurans is governed by a second-order reaction. Only the decay of the radical anion generated from 5-nitro-2-furfural III may be described by an equation including parallel first- and second-order reactions; this behaviour is evidently caused by the relatively high stability of the corresponding dianion, this being an intermediate in the reaction path. The presence of a larger conjugated system in the substituent in position 2 results in a decrease of the unpaired electron density in the nitro group and, consequently, an increase in the stability of the corresponding radical anions.