Anticorrosion Agents for Carbon Steel in Acidic Environments: Synthesis and Quantum Chemical Analysis of New Schiff Base Compounds with Benzylidene

Abstract

Novel Schiff bases (SBs), namely, N 1 ,N 2 -bis(2-(((E)-4-chlorobenzylidene)amino)ethyl)ethane-1,2-diamine (I), N 1 ,N 2 -bis(2-(((E)-4-(dimethylamino)benzylidene)amino)ethyl)ethane-1,2-diamine (II), and N 1 ,N′ 1 -(ethane-1,2-diyl)bis(N 2 -((((Z)-4-dimethylamino)benzylidene) amino)methylethane-1,2diamine) (III), were prepared and characterized by using elemental analysis, IR, and 1 H NMR spectroscopy. For assessing carbon steel in diverse settings, with and without inhibitors at varying concentrations, electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) techniques were employed. The results showed that the synthesized inhibitors effectively decreased the corrosion rate of carbon steel in acidic media and the inhibition efficiency reached up to 93% for compound III at a concentration of 250 ppm. In addition, all prepared compounds were successful as anticorrosion agents, and the inhibition mechanism followed chemisorption from the Langmuir isotherm. The data obtained from the theoretical analysis show that the efficiency of the prepared compounds was in the order III < II < I. Furthermore, quantum chemical calculations were performed to gain insight into the electronic structure of the compounds. The analysis of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) showed that compound III had the highest surface coverage due to its specific molecular structure and spacer. This observation agreed well with the Langmuir adsorption data.

Fabrication of Protective Organic Layer Using Schiff-Base Metal Complex Responsible for Excellent Corrosion Performance: Experimental and Theoretical Perspectives

“…In another recent study, Thabet et al discussed the potential for corrosion inhibition of three SBs for CS in 1 M HCl. The inhibitory performance achieved 93% at a concentration of 250 ppm . In their study, Zobeidi et al synthesized three compounds derived from SBs to explore their ability to inhibit acid corrosion of XC70 steel in 1 M HCl.…”

“…The inhibitory performance achieved 93% at a concentration of 250 ppm. 17 In their study, Zobeidi et al synthesized three compounds derived from SBs to explore their ability to inhibit acid corrosion of XC70 steel in 1 M HCl. The results indicated that the highest degree of inhibition observed at a concentration of 6 × 10 –5 M, was 87.27%.…”