Coordination-mediated radical nitration of methyl salicylate by ferric nitrate

Abstract

Nitration of methyl salicylate was performed by ferric nitrate in refluxing ethyl acetate solution. A coordination-mediated radical nitration process was proposed based on the results of electronic absorption spectra, cyclic voltammetry and electrospray ionization mass spectra. It was the coordination of methyl salicylate with ferric nitrate that promoted the splitting of N-O bonds of nitrate group in ferric nitrate and resulted in the formation of nitro radicals, oxygen radicals and complex radicals. The nitro radicals reacted with methyl salicylate or its complexes with iron to give a series of nitration products and Fe(II) ions. Meanwhile, oxygen radicals hydrolyzed to hydroxide which precipitated free ferric ions to isolate solid ferric oxides.