Synthesis, crystal structure, experimental and theoretical studies of corrosion inhibition of 2-((4-(2-hydroxy-4-methylbenzyl)piperazin-1-yl)methyl)-5-methylphenol - A Mannich base

A new Mannich base; 2-((4-(2-hydroxy-4-methylbenzyl)piperazin-1-yl)methyl)-5-methylphenol (HMP) was synthesized, characterized by elemental analysis, UV/Vis, H-1 and C-13 NMR spectroscopy, and examined as an inhibitor for the corrosion of a mild steel surface in 0.2 M sulphuric acid (H2SO4) solution using weight loss and potentiodynamic polarization techniques. The X-ray structure of the Mannich base was also reported. The inhibition efficiency increases with increasing inhibitor concentration and decreases over 96 h. Potentiodynamic polarization measurements showed that the inhibitor is of mixed type. The relationship between the molecular structure of HMP and its inhibitory properties was studied using density functional theory (DFT) calculations. (C) 2020 Elsevier B.V. All rights reserved.