Applicability of some new pyrimidine derivatives for the corrosion inhibition of mild steel in the acidic environment

• Published in: South African journal of chemical engineering 2024-04, Vol.48, p.80-94
• Main Authors: Rasheeda, Kedila, Swathi, N. Phadke, Alva, Vijaya D.P., Samshuddin, Seranthimata, Aljohani, Talal A., Baig, Irshad, Alomari, Fatimah Y., Alamri, Aeshah Hassan
• Format: Article
• Language: English
• Subjects: Acid media; C1018 steel; Corrosion inhibition; Pyrimidine derivatives; Quantum calculation; SEM
• ISSN: 1026-9185
• DOI: 10.1016/j.sajce.2024.01.006

•A new corrosion inhibitors, ethyl 4[4-(dimethylamino)phenyl]-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate (ESP) and 4-[4-(dimethylamino)phenyl]-6-methyl-N-phenyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DSP), have been synthesized and their structures were confirmed by the spectral data.•The anticorrosion property of DSP and ESP on carbon steel were analyzed by electrochemical methods, which revealed that DSP and ESP are an excellent corrosion inhibitors.•The electrochemical studies indicated that DSP and ESP are mixed type inhibitors and get adsorbed on the metal surface by both, physisorption and chemisorption mechanisms.•SEM–EDX studies confirmed the formation of protective inhibitory film of DSP and ESP on the surface of carbon steel.•Quantum chemical parameter obtained from DFT and Monte Carlo simulation studies also supported the data obtained from experimental studies. The current work targets to discover the potential of two pyrimidine derivatives, ethyl 4-[4-(dimethylamino)phenyl]-6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxylate (ESP) and 4-[4-(dimethylamino)phenyl]-6-methyl-N-phenyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidine-5-carboxamide (DSP), for the protection of C1018 steel from acidic corrosion. Electrochemical tests like electrochemical impedance spectroscopy, linear polarization resistance, potentio-dynamic polarization, and electron frequency modulation were employed for assessing the anticorrosive capability of the synthesized ESP and DSP. Both ESP and DSP inhibitors exhibited great inhibition activity, and the inhibition effectiveness attained 88.6 % for ESP and 94.9 % for DSP at saturation concentration. EIS data for ESP and DSP exposes that inhibition efficacy enhances with an increase in the doses of the two inhibitors by creating a protective film. The finest explanation for the adsorption of the examined molecules on the Fe surface was provided by the Langmuir model. The surface morphology was also evaluated by using SEM and EDX techniques. Computational studies like DFT and MC simulation methods were employed to determine the connection between anticorrosion performance and the inhibitor structure, which agrees with the experimental outcomes.