表面増強ラマン散乱分光法によるN-置換アニリンの腐食抑制機構の研究

抄録

Inhibition mechanism of N-substituted anilines has been studied on iron corrosion in a hydrochloric acid solution by polarization measurements [This Journal, 28, 77 (1979)]. According to the linear free energy relationship, it has been concluded that a parameter Ψ_r, which denotes an effect of resonance structures on adsorption of the inhibitors, decreases in the order, aniline>N-methyl aniline>N, N-dimethylaniline. In this work, adsorption behavior of these anilines on iron in 0.5N HCl was investigated by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra of these compounds showed that anilinium ions of the compounds are electrostatically adsorbed on the iron surface and a molecule of N, N-dimethylaniline is chemisorbed in part on the surface by the formation of an Fe-N coordinate bond. It was suggested that anilinium ion is adsorbed parallel to the surface via π-electron interaction and N-methylanilinium and N, N-dimethylanilinium ions are adsorbed in a tilted orientation. These results support the order of Ψ_r for the N-substituted anilines.