The azo Schiff base [Reaction of salicylaldehyde and 2-aminothiophenol] and anthranilic acid have been prepared. One azo Schiff base chelate of copper(II) ion was also prepared. The chemical structures of the azo Schiff base and its chelate were confirmed by various physiochemical analyses such as, CHNS elemental analyses, molar conductance measurements, IR, 1H NMR, mass and EPR spectroscopy. The CHNS elemental analyses showed the formation of 2:1[M:L] ratio. Based on the IR spectral data, it is found that the azo Schiff base compound acts as neutral tridentate ligand when the metal ion bonded from the Schiff base side and neutral bidentate ligand when the metal ion bonded from the azo side. The entering of hydroxyl, azomethine and thiol groups of the azo Schiff base compound in chelation was confirmed by IR and 1H NMR spectral results. The electronic spectral data displayed the presence of π→π* (phenyl ring), n→π* (-OH, HC=N and SH) and a square planar geometry was pointed out for the chelate. The mass spectral results confirmed the purity of the azo Schiff base and its chelation. The corrosion inhibition of mild steel in acidic media 0.5M HCl using the azo Schiff base and its Cu(II) chelate as corrosion inhibitor was studied by weight loss method. The obtained results showed that the azo Schiff base chelate efficiently inhibited acidic corrosion.
Keywords: Azo Dye; Schiff Base; 2-Aminothiophenol; Anthranilic Acid; Corrosion Inhibition