Role of electron transfer in reactions involving substitution of halogen in 2-halo-5-nitrofurans

The replacement of the halogen in 2-halo-5-nitrofurans (Hal=C1, Br, I) in dimethylformamide (DMF) under the influence of tetra-n-butylammonium hydroxide to give 2-hydroxy-5-nitrofuran salts was studied. The intermediate anion radicals of the halonitrofurans were recorded by EPR spectroscopy; bromo- and iodonitrofurans can give 5,5-dinitro-2,2-difuryl anion radicals under the influence of Bu₄NOH. The polarographic reduction of halonitrofurans in the presence of hydrogen peroxide also leads to 2-hydroxy-5-nitrofuran. A mechanism for the transformation is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1604–1607, December, 1979Original article submitted March 17, 1977; revision submitted October 30, 1978.