Abstract Two new salts of 8-hydrxyquinoline namely: sodium 5-methylthio-8-hydroxyquinolinolate (SMQ) and sodium 5-propylthio-8-hydroxyquinolinolate (SPQ) have been prepared and identified via elemental analyses, Fourier-transform infrared spectroscopy (FTIR) and NMR spectroscopic. Both salts also have been assessed as new organic inhibitors for the corrosion of steel C22E in a molar electrolyte of hydrochloric acid utilizingelectrochemical, gravimetric and theoretical calculation studies. The weight reduction investigation indicated that the rate of corrosion regularly decreased by increasing the concentration of 5-alkylthio-8-hydroxyquinolines in acidic electrolyte. The polarization study data demonstrate that 5-alkylthio-8-hydroxyquinolines have an excellent inhibitive performance for C22E steel in 1 M HCl and behave like mixed-type inhibitors. However, the efficiency of SPQ and SMQ achieved up to 95.8% and 92.1% at 10–3 M, respectively. The impedance experimental results show the frequency distribution of the capacitance, simulated as a constant phase element. The adsorption of synthesized salts complied with the Langmuir's adsorption isotherm and the estimated thermodynamic parameters proposed a combination of physisorption and chemisorption mechanisms. The calculated value of the adsorption-desorption equilibrium constant (797,073 L/mol and 377,182 L/mol) reveals a strong bonding between SPQ and SMQ molecules, respectively, and the steel surface. The inhibition performance for SPQ and SMQ was confirmed by SEM. The results found from theoretical calculations, including the density functional theory (DFT) method and molecular dynamics (MDS) simulations, support the experimental results and explain in a general way how anionic forms adsorb on the iron surface.

中文翻译：

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盐酸摩尔电解液中两种5-烷硫基-8-羟基喹啉盐对钢C22E的抑制作用：实验和理论研究

摘要 制备了两种新的 8-羟基喹啉盐，即 5-甲硫基-8-羟基喹啉钠 (SMQ) 和 5-丙硫基-8-羟基喹啉钠 (SPQ)，并通过元素分析、傅里叶变换红外光谱 (FTIR) 进行鉴定。和核磁共振光谱。利用电化学、重量分析和理论计算研究，这两种盐也被评估为在盐酸摩尔电解质中腐蚀钢 C22E 的新型有机抑制剂。减重研究表明，随着酸性电解液中 5-烷硫基-8-羟基喹啉浓度的增加，腐蚀速率有规律地降低。极化研究数据表明，5-烷硫基-8-羟基喹啉在 1 M HCl 中对 C22E 钢具有优异的抑制性能，并且表现得像混合型抑制剂。然而，SPQ 和 SMQ 的效率在 10-3 M 时分别达到了 95.8% 和 92.1%。阻抗实验结果显示了电容的频率分布，模拟为恒定相位元件。合成盐的吸附符合朗缪尔吸附等温线，估计的热力学参数提出了物理吸附和化学吸附机制的组合。吸附-解吸平衡常数的计算值（797,073 L/mol 和 377,182 L/mol）分别表明 SPQ 和 SMQ 分子与钢表面之间有很强的结合。SEM 证实了 SPQ 和 SMQ 的抑制性能。从理论计算中发现的结果，包括密度泛函理论 (DFT) 方法和分子动力学 (MDS) 模拟，