Pyrazole derivatives as environmental benign acid corrosion inhibitors for mild steel: Experimental and computational studies

Four industrially relevant pyrazole derivatives (PYRs) differing in their nature of substituents were synthesized by an eco-friendly one-pot multicomponent reaction (MCR), and their acid corrosion inhibition was studied for mild steel using experimental and computational approaches. Results revealed that the inhibition capability of PYRs was substituent-and concentration-dependent. Even though the efficiency increases in the existence of both the electron-withdrawing and the electron-releasing substituents, the best inhibition efficiency was achieved in the presence of electron releasing (–OH, –OHOCH₃) groups. The inhibition efficiency of the studied PYRs followed the order: PYR–OHOCH₃ (94.88%) > PYR–OH (91.47%) > PYR–NO₂ (90.90%) > PYR–H (89.77%). Electrochemical studies suggested that PYRs functioned as mixed-type inhibitors and their adsorption obeyed the Langmuir isotherm. The interactions between PYRs and metallic surface were explained using DFT and MD simulations, and correlated with the experimental results.