The newborn surface of dull metals in organic synthesis. Bismuth-mediated solvent-free one-step conversion of nitroarenes to azoxy- and azoarenes

When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.