MECHANISM OF THE ELECTROCHEMICAL REDUCTION OF 2-HALO-5-NITROTHIOPHENES IN DIMETHYLFORMAMIDE

Article abstract of DOI:10.1007/BF00507243

The reduction of 2-bromo-5-nitrothiophene and 2-iodo-5-nitrothiophene in dimethylformamide (DMF) was studied by means of classical and commutated polarography, EPR spectroscopy, a rotating platinum disk electrode with a ring, and preparative electrolysis.It was established that, depending on the nature of the halogen, their anion radicals may undergo further reduction to 2-nitrothiophene anion radicals or decomposition with splitting out of a halide anion and conversion to nitrothienyl radicals, which were identified on the ring electrode.The latter are capable of undergoing dimerization to 2,2'-dinitro-5,5'-dithienyl.The spectra of the anion radicals of 2-nitrothiophene and 2,2'-dinitro-5,5'dithienyl were recorded by means of EPR.A mechanism for the reduction of halonitrothiophenes is proposed.