Synthesis, characterization, theoretical, and evaluation of eco-friendly phenytoin-based corrosion inhibitors for mild steel

This study explores the corrosion inhibition potential of two newly synthesized phenytoin-based compounds, (E)-2-(2-(2-chlorobenzylidene)hydrazineyl)-5,5-diphenyl-3,5-dihydro-4H-imidazol-4-one (2-ClPh-DDI) and (E)-2-(2-(2,4-dichlorobenzylidene)hydrazineyl)-5,5-diphenyl-3,5-dihydro-4H-imidazol-4-one (2,4-diClPh-DDI), in 1 M HCl solution. Both compounds exhibited remarkable inhibition efficiencies, reaching 97.7 % and 98.6 %, respectively. Comprehensive structural characterization was conducted using fourier-transform infrared spectroscopy, nuclear magnetic spectroscopy, and high-resolution mass spectrometry, both inhibitors demonstrated high purity and stability. Theoretical evaluations, including Monte Carlo simulation and density functional theory calculations, confirmed high reactivity and strong inhibition capabilities. Electrochemical measurements demonstrated a concentration-dependent inhibition effect, sustained up to 328 K. Adsorption isotherms revealed that these inhibitors effectively displace water molecules, forming a robust adsorbed layer that protects the mild steel surface. Surface analysis using microscopy confirmed the formation of protective layers and the presence of iron-inhibitor complexes, highlighting the compounds’ effectiveness in mitigating corrosion. The combined experimental and theoretical insights underscore the promising role of these phenytoin derivatives as eco-friendly corrosion inhibitors for mild steel.