Performance of newly synthesized pyrimidine derivative as corrosion inhibitor: experimental and quantum chemical investigation

Abstract

In this investigation, an alternative Schiff base with a pyrimidine ring was produced through the reaction of (1-amino-4-phenyl-2-thioxo-1,2-dihydropyrimidin-5-yl)(phenyl)methano-ne (1) with thiophene-2-carboxaldehyde. Structural verification of the resulting compound, designated (E)-phenyl (4-phenyl-1-(thiophen-2-ylmethyleneamino)-2-thioxo-1,2-dihydropy-rimidin-5-yl)methanone, (PPTT), was accomplished by employing a number of spectroscopic methods, including 13 C-NMR, 1 H-NMR, and FTIR. Open-circuit potential, potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy were among the electrochemical methods used to evaluate the efficacy of PPTT as a corrosion inhibitor. After one hour of immersion, experimental data showed that PPTT functioned as a mixed-type corrosion inhibitor, achieving up to 83.8% inhibition for 2 mM PPTT in 1 M HCl solution. Under these conditions, the corrosion current density dropped from 123.2 to 31.4 μA cm -2 . Surface adsorption of PPTT on mild steel in 1 M HCl followed the Langmuir adsorption isotherm, consistent with a negative Gibbs free energy value, indicating both chemisorption and physiosorption. In addition, multiple quantum chemical parameters (electronegativity, EHOMO, ELUMO, chemical hardness, chemical softness) were calculated using Gaussian 09 to further elucidate the experimental observations.