New cyclic imides linked to oxadiazole derivatives: synthesis, characterization and anticorrosion study

In this study, a series of novel cyclic imides linked to imidazopyridine was synthesized through multi-step reactions.The synthesis began with the reaction of 2-aminopyridine and 4-bromophenacyl bromide to obtain 2-(4-bromophenyl)imidazo[1,2-a]pyridine (A1).This intermediate was further reacted with 2-aminobenzoic acid under acid conditions to give the Mannich base (A2), followed by ring closure using semi carbazide and POCl3, yielding 2-aminooxadiazole (A3).Subsequent reactions with different anhydrides produced amic acid derivatives (A4-A6), which were cyclized into novel cyclic imides (A7-A9) via thermal dehydration.The synthesized compounds were characterized by 1 H NMR, 13 C NMR, and FT-IR spectroscopy.Electrochemical anticorrosion studies were conducted for compounds A7-A9 using potentiodynamic polarization techniques in 1 M HCl solution, revealing significant inhibition efficiency.Among the tested compounds, A9 exhibited the highest protection efficiency, correlating well with computational results obtained via Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations.These results highlight the potential application of these novel cyclic imides as effective corrosion inhibitors for carbon steel.