Synthesis and structural characterization of some novel methoxyamino derivatives with acid-base and redox behavior

Abstract

A series of novel derivatives of 3,5-dinitro-4-methoxyamino-benzoic acid were synthesized and fully characterized. Synthesis were performed by simple coupling reactions of the starting material with benzylamine, n-butylamine, 4-amino-antipyrine, benzocaine, 3,4-dimethyl-5-amino-isoxazole, 3,4-dimethoxyphenyl-2-ethylamine; besides, the corresponding methyl ester was also synthesized. The structural characterization of the new compounds was made by elemental analysis, IR, 1H and 13C NMR, UV–Vis, ESR, cyclic voltammetry, and single crystal X-ray diffraction (where appropriate). All compounds exhibits reversible acid-base behavior accompanied by colour change (yellow in acid media and blue at basic pH). Cyclic voltammetry showed an irreversible oxidation peak, however by chemical oxidation, these compounds generates persistent free radicals, evidenced also by ESR. Hydrophobicity and total antioxidant capacity of the compounds were also evaluated.