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• Synthesis and spectroscopic characterizations of new 1-(2,5-dimethoxy-4-methylphenyl)ethan-1-thiosemicarbazone molecules. • With an optimal dose (1.5 mM) the efficiency of inhibition reached 96% at 298 K in 1 M HCl. • Polarization measurements indicate that compound 4 exhibits a mixed-type corrosion inhibition mechanism. • The adsorption of compound 4 on the iron surface was demonstrated by DFT calculations as well as the dynamic Monte Carlo simulations. • Theoretical data provide an in-depth understanding of the experimental results. In this report, a thiosemicarbazone, namely, 1-(2,5-dimethoxy-4-methylphenyl) ethan-1-thiosemicarbazone 4 was synthesized from naturally occurring para methoxy-thymol and investigated as a new corrosion inhibitor on carbon steel in 1 M HCl solution, using combined experimental and theoretical explorations. Weight loss, potentiodynamic polarization (PDP), impedance spectroscopy (EIS), and Scanning Electron Microscopy (SEM) were used to research the inhibition performance and determine the adsorption distribution characteristics of compound 4. The obtained results revealed that this obtained molecule has a high corrosion inhibitory power for carbon steel in 1M HCl and its inhibition efficacy reaches a value of 96% at 1.5 mM compound 4. The results further revealed that compound 4 functions as an effective mixed-type inhibitor. Density function theory (DFT) and molecular dynamics simulations were also adopted to provide a robust representation of corrosion phenomena in realistic conditions. The structure synthesized was confirmed by NMR (1H & 13C), IR, and high-resolution mass spectroscopy (HRMS). [ABSTRACT FROM AUTHOR]

• The molecule bis-isoxazoline (3) is used as a very effective corrosion inhibitor in hydrochloric acid. • The maximum inhibitory efficiency measured is 92 % and mixed type inhibitor. • Chemisorption is the mechanism of the inhibition process with the release of energy. A series of C(3)-mono-substituted isoxazoline of type mono- and bis-isoxazoline, have been prepared from (R)-carvone 1 in a two-step procedure. First, (R)-carvone was treated with O -methoxy-benzaldoxime via a 1,3-dipolar cycloaddition reaction. The resulting mono-isoxazoline 2 was then converted into bis-isoxazoline(3) , followed by an optimization study on the yield by varying the number of the equivalent of O -methoxy-benzaldoxime. The structures of mono- and bis-isoxazoline(3) newly synthesized were fully identified based on their HRMS and NMR spectral data. The bis-isoxazoline compound was used to evaluate the anticorrosion effect. The inhibitory properties of bis-isoxazoline-carvone(3) were evaluated using a variety of methods including weight loss(wl), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface morphology analysis (SEM), quantum chemical calculations (DFT), and Monte Carlo simulation (MC). The results of (PDP) show that compound(3), which is a mixed type inhibitor, significantly reduces the corrosion rate of carbon steel (CS) through the creation of a protective film on the metal surface. According to EIS, SEM and theoretical studies, a bis-isoxazoline-carvone(3) is a better corrosion inhibitor with higher corrosion rates of about 92% at 298 K. The Langmuir isothermal model is the most appropriate to describe the adsorption of bis-isoxazoline-carvone(3) on the surface was mixed (chemisorption and physisorption). [ABSTRACT FROM AUTHOR]

[Display omitted] • The molecule 3-(2-methoxyphenyl)-isoxazole-carvone is used as a very effective corrosion inhibitor in hydrochloric acid. • The maximum inhibitory efficiency measured is 94.73 %. • Chemisorption is the mechanism of the inhibition process with the release of energy. A novel mono-isoxazole was synthesized from (R)-Carvone and O -methoxy-benzaldoxime, via a [3 + 2] cycloaddition reaction. The newly obtained mono-isoxazole has been fully characterized by HRMS and NMR spectroscopy.3-(2-methoxyphenyl)-isoxazole-carvone (MIC) was synthesized and studied for its anti-corrosion effect on carbon steel in 1 M HCl at 298 K. The study was carried out using weight loss, electrochemical tests and surface analysis. It was found that 3-(2-methoxyphenyl)-isoxazole-carvone (MIC) has the best inhibition performance reaching up to 94% at 1.34 mM, the polarization curves demonstrate that the investigated molecule acts as a mixed type inhibitor with a cathodic predominance. The MIC adsorbed chemically and physically on the surface of carbon steel and followed the Langmuir adsorption isotherm model. DFT method was used to investigate the global and local reactivity of our compound and also it's behaviour when complexing with one iron atom. The molecular dynamics simulation results show that MIC compound can adsorb on the iron (1 1 0) surface through the oxygen and nitrogen atoms as well as p-electrons in the Phenyl ring. [ABSTRACT FROM AUTHOR]