Theoretical Evaluation of the Corrosion Inhibition Performance of an Organic Heterocyclic Compound

Abstract

The corrosion inhibition performance of a corrosion inhibitor on mild steel in phosphoric acid, namely 5-chloro-1-(2-(dimethylamino) ethyl) indoline-2,3-dione (TZCDI), was theoretically evaluated using density functional theory (DFT) at the B3LYP/6-31G+(d,p) level for all atoms by Gaussian 09W program. The quantum chemical properties, such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO) energy gap (∆Egap), dipole moment (μ), total hardness (η), and electronegativity (χ), were studied, and these descriptors were discussed in connection to the experimental inhibitory efficiency. The local reactivity was analyzed through the Fukui function in order to compare the possible sites for nucleophilic and electrophilic attacks. Accordingly, all data obtained using various theoretical calculation techniques were consistent with experiments.