Polarographic study of the conduction of the polar effect of a substituent through the furan ring and side bridge groupings

Abstract

The coefficients of conduction of the polar effect of a substituent through the furan ring and side bridge groupings were calculated by comparison of the polarographic half-wave potentials for the electroreduction of the nitro group in series of 5-substituted derivatives of 2-nitrofuran and p-substituted nitrobenzene derivatives by means of the ρ -ρ method. The polarographic method can be successfully used for this purpose in media in which the electrochemical process is not limited by the kinetics of the side process of surface protonation of the nitro group. It follows from the polarographic data and hyperfine structure of the ESR spectra of the anion radicals that the furan ring conducts the polar effect of substituents better (by a factor of 1.1–1.2) than the benzene ring. Depending on the electronic structure of the bridge groups, the introduction of bridge groups between the furan ring and the substituent decreases the conduction of the effect of substituents.