Study of Aniline Derivatives as Corrosion Inhibitors With Density Functional Theory (DFT) Calculations

Some aniline Derivatives as organic corrosion inhibitors were selected and the inhibition effects of these compounds was studied with density functional theory (DFT) calculations. Some aniline derivatives containing substituted halides (except I), alkyls (methyl, isoporopyl and ter-butyl), OH, SH, NH2, OCH3 and NO2 were selected. For this purpose some electronic parameters such as EHOMO, ELUMO, the energy gap (ΔE), dipole moment (μ), electronegativity (χ), global hardness (η), the fraction of electrons transferred (ΔN) as well as the thermodynamic parameters such as standard Gibbs free energy (ΔGᵒ ) and standard reduced potential (Eᵒ ) were calculated. In order to find optimized structures and determination of quantum chemical parameters related to corrosion, the calculations were performed by using Gaussian software with DFT/B3LYP method and 6- 311++G(d,p) basis set in the gaseous and aqueous phases. After performing the calculations, it was determined that the most appropriate position on the aniline ring is para position. The NH2 > OCH3 > OH > SH > aniline and halides < alkyls > NO2 order was obtained by comparing their inhibitory properties based on the ΔN and E° parameters. The results of the calculations of the derivatives containing methyl or methoxy groups and last experimental studies are in good agreement. Both studies show the order of inhibition for compounds as para> ortho> meta, confirming the validity of the calculations.