Synthesis of 3,4,5-trihydroxy-2-[(hydroxyimino) methyl] benzoic acid as a novel rust converter

A new rust converter, 3,4,5-trihydroxy-2-[(hydroxyimino) methyl] benzoic acid (named as RC-GAO), has been synthesized based on gallic acid by formylation and oximation. The synthesis was confirmed by Fourier transform infrared spectroscopy studies. The nature and morphology of rust and conversion layer on the rusty samples were characterized by scanning electron microscopy and X-ray diffraction. The corrosion resistance of the residual rust coatings containing the rust converter on the rusty sample was measured by the salt spray test. The results showed that the synthesized rust converter possessed excellent chelating capability with rust and significant anticorrosive performance.