Reaction of 2-halo-5-nitropyridines with hydroxide ion in dimethyl sulfoxide

Addition of aqueous base to solutions of 2-halc-5-nitropyridines in dimethyl sulfoxide produces a stable substance which forms 2-hydroxy-5-nitropyridine if the molar ratio of hydroxide to pyridine is greater than 2:l. IR and 'H and 13C NMR spectra of the intermediate stable substance indicate that the pyridine ring is cleaved to form this material. An SN(ANRORC) mechanism is proposed for the reaction.