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<p>We report the first demonstration of an ultrasound-assisted, SnCl<sub>2</sub>·2H₂O-catalyzed one-pot green synthesis of ten 3,4-dihydropyrimidin-2(1<i>H</i>)-one (DHPM) derivatives via the Biginelli reaction of various aromatic aldehydes with ethyl acetoacetate and urea in ethanol at 30&#xa0;°C. The optimized protocol utilizes ultrasound irradiation to significantly accelerate reaction rates, yielding DHPMs in excellent isolated yields (79–98%) within 1–2&#xa0;h. Structural characterization was performed using FT-IR and <sup>1</sup>H/<sup>13</sup>C NMR spectroscopy, confirming product integrity. The corrosion inhibition efficiencies of the synthesized DHPMs were evaluated for mild steel in 0.5&#xa0;M HCl using potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS). Among the tested derivatives, the 2,3-dichlorophenyl-substituted DHPM exhibited the highest inhibition efficiency of ~ 90.1% (Tafel) and ~ 80.5% (EIS), with a marked increase in charge-transfer resistance (<i>R</i><sub>ct</sub> ≈ 72 Ω cm<sup>2</sup>). All compounds acted as mixed-type inhibitors, showing both anodic and cathodic protection mechanisms. The influence of substituents on corrosion inhibition followed expected electronic trends, with halogenated derivatives outperforming those with electron-donating or bulky groups. This study highlights the synergistic role of ultrasound and SnCl<sub>2</sub>·2H₂O in enabling an efficient, environmentally friendly synthesis of tunable DHPM-based corrosion inhibitors.</p> Graphical abstract <p></p>

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Ultrasound-accelerated green synthesis of dihydropyrimidinones as efficient corrosion inhibitors: SnCl2·2H₂O-catalyzed one-pot strategy

  • 期刊论文

  • 发表日期：

    2026年8月3日

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  • Gunjan Salaria,
  • Monika Verma,
  • Ruchi Bharti,
  • Renu Sharma,
  • Shivani Naik

摘要

We report the first demonstration of an ultrasound-assisted, SnCl2·2H₂O-catalyzed one-pot green synthesis of ten 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives via the Biginelli reaction of various aromatic aldehydes with ethyl acetoacetate and urea in ethanol at 30 °C. The optimized protocol utilizes ultrasound irradiation to significantly accelerate reaction rates, yielding DHPMs in excellent isolated yields (79–98%) within 1–2 h. Structural characterization was performed using FT-IR and 1H/13C NMR spectroscopy, confirming product integrity. The corrosion inhibition efficiencies of the synthesized DHPMs were evaluated for mild steel in 0.5 M HCl using potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS). Among the tested derivatives, the 2,3-dichlorophenyl-substituted DHPM exhibited the highest inhibition efficiency of ~ 90.1% (Tafel) and ~ 80.5% (EIS), with a marked increase in charge-transfer resistance (Rct ≈ 72 Ω cm2). All compounds acted as mixed-type inhibitors, showing both anodic and cathodic protection mechanisms. The influence of substituents on corrosion inhibition followed expected electronic trends, with halogenated derivatives outperforming those with electron-donating or bulky groups. This study highlights the synergistic role of ultrasound and SnCl2·2H₂O in enabling an efficient, environmentally friendly synthesis of tunable DHPM-based corrosion inhibitors.

Graphical abstract