In situ synthesis, electrochemical, surface morphological, UV-visible, DFT and Monte Carlo simulations of novel 5-substituted-8-hydroxyquinoline for corrosion protection of carbon steel in a hydrochloric acid solution

Two new organic compounds based on 8-hydroxyquinoline have been successfully synthesized, and characterized by FT-IR, 1H, C-13 NMR and Elemental analysis. The synthesized compounds namely tert-butyl((8-hydroxyquinolin-5-yl)-methyl)-carbamate (BHQC) and Ethyl 3-(((8-hydroxyquinolin-5-yl)-methyl)-amino)-3-oxopropanoate (EHQP) are evaluated as corrosion inhibitors for carbon steel (CS) in 1 M HCl solution using electrochemical techniques, UV - visible and SEM at 298 K. Electrochemical measurements showed that these organic compounds are mixed type inhibitors. The adsorption of both inhibitors on the carbon steel surface followed Langmuir adsorption isotherm. Furthermore, DFT calculations and Monte Carlo simulation were performed to theoretically establish the relationship between molecular structure and inhibition efficiency. (C) 2019 Elsevier B.V. All rights reserved.