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<p>Castor oil was converted into low-molecular-weight, hydroxyl-functional polyol mixtures through a sequential acid–base liquefaction route, and the influence of reaction sequence on ester-linkage cleavage behavior and product distribution was evaluated in comparison with alkali-only caustic fusion and single-catalyst control reactions. In the sequential process, an acid-catalyzed first step promoted initial ester scission, while subsequent neutralization and mild alkaline treatment shifted the product distribution toward lower-molecular-weight, tetrahydrofuran-soluble species. Molecular-weight characteristics were assessed by gel permeation chromatography and are discussed as apparent values obtained under a consistent calibration protocol. Under the optimized sequential condition, the resulting polyol exhibited a lower apparent number-average molecular weight (Mn ≈ 519&#xa0;g/mol), a narrower apparent molecular-weight distribution, and the highest low-molecular-weight fraction within the 300–700&#xa0;g/mol range (51.4%) among the routes evaluated. Fourier-transform infrared analysis showed reduced ester carbonyl intensity together with increased hydroxyl-related absorption, consistent with progressive ester cleavage and hydroxyl generation. The sequential product also showed the highest hydroxyl value (1053.7&#xa0;mg KOH/g), indicating enhanced formation of hydroxyl-functional low-molecular-weight species. Compared with the acid-only and base-only treatments, the sequential route provided a favorable balance between molecular-weight reduction and product uniformity within the tested analytical framework. These results indicate that sequential acid–base liquefaction provides a practical comparative route to low-molecular-weight castor-oil-derived polyol precursors with a narrower apparent molecular-weight distribution.</p>

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Sequential acid–base liquefaction of castor oil for low-molecular-weight polyol precursors

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Young Chan Jeon,
  • Jin-Gyu Min,
  • Won-Bin Lim,
  • Ju-Hong Lee,
  • Jae-Ryong Lee,
  • Seoung-Ho Kim,
  • Ji-Hong Bae,
  • PilHo Huh

摘要

Castor oil was converted into low-molecular-weight, hydroxyl-functional polyol mixtures through a sequential acid–base liquefaction route, and the influence of reaction sequence on ester-linkage cleavage behavior and product distribution was evaluated in comparison with alkali-only caustic fusion and single-catalyst control reactions. In the sequential process, an acid-catalyzed first step promoted initial ester scission, while subsequent neutralization and mild alkaline treatment shifted the product distribution toward lower-molecular-weight, tetrahydrofuran-soluble species. Molecular-weight characteristics were assessed by gel permeation chromatography and are discussed as apparent values obtained under a consistent calibration protocol. Under the optimized sequential condition, the resulting polyol exhibited a lower apparent number-average molecular weight (Mn ≈ 519 g/mol), a narrower apparent molecular-weight distribution, and the highest low-molecular-weight fraction within the 300–700 g/mol range (51.4%) among the routes evaluated. Fourier-transform infrared analysis showed reduced ester carbonyl intensity together with increased hydroxyl-related absorption, consistent with progressive ester cleavage and hydroxyl generation. The sequential product also showed the highest hydroxyl value (1053.7 mg KOH/g), indicating enhanced formation of hydroxyl-functional low-molecular-weight species. Compared with the acid-only and base-only treatments, the sequential route provided a favorable balance between molecular-weight reduction and product uniformity within the tested analytical framework. These results indicate that sequential acid–base liquefaction provides a practical comparative route to low-molecular-weight castor-oil-derived polyol precursors with a narrower apparent molecular-weight distribution.