Anticorrosive Behavior of New Pyrimidine Derivatives on Carbon Steel in Acidic Medium: Experimental, Theoretical, and Surface Studies

Designing a new organic inhibitor with solubility in an acid medium for the anticorrosion of carbon steel is a great deal. In this study, new pyrimidine derivatives bearing a good electron-donating bond, namely 4-[4-(dimethylamino)phenyl]-6-methyl-2-oxo-N-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DTP) and ethyl 4-[4-(dimethylamino)phenyl]-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (ETP), were designed and synthesized. The inhibitory effect of ETP and DTP on the corrosion of C1018 steel in 1.0 M HCl has been studied by electrochemical and theoretical studies. The potentiodynamic polarization results for ETP and DTP clearly show the mixed-type nature of the inhibitors but are predominantly anodic. EIS data for both inhibitors showed that an increase in the concentration of inhibitor increases the polarization resistance and inhibition efficacy, reducing the double-layer capacitance. However, DTP is slightly more efficient than ETP (91.7% compared with 89.2% at 750 ppm). The adsorption behavior of both inhibitors on the C1018 surface follows the Langmuir isotherm model. The SEM/EDX results indicated the development of shielding film on the C1018 surface after the addition of ETP and DTP. Computational studies such as DFT and MD simulation have been applied to investigate the relationship between the molecular properties of the inhibitors with experimental results. Theoretical studies for both inhibitors perfectly correlate with the results obtained from the experimental findings. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.