Catalytic conversions of biomass‐derived compounds like 5‐hydroxymethylfurfural (HMF) and levulinic acid (LA) to value‐added compounds have drawn tremendous interest in recent years. In this study, we report the catalytic upgrading of HMF into HMF levulinate and HMF esters under solvent‐free condition using laboratory‐synthesized bifunctional ionic liquid (IL) catalysts. The synthesized ILs were characterized using ¹H NMR and ¹³C NMR spectroscopy. Pyridine Fourier transform Infrared spectroscopy (FT‐IR) studies were carried out for their detailed Brønsted and Lewis acidity characterization. Catalytic activity of these ILs was tested in the conversion of HMF into HMF levulinate in the temperature range of 75 to 120 °C and 5 h reaction time using 150 mg each of IL catalyst and 4 Å molecular sieves with LA to HMF molar ratio of 5:1. It was found that strong dual acidic catalyst [SMIM][FeCl₄] was found to exhibit highest catalytic activity with 97.0% HMF conversion and 78.1% yield of HMF levuliante. Catalytic activity decreased in the order: [SMIM][FeCl₄]> [BSO₃HMIm][FeCl₄]> [SMIM][Cl]> [BSO₃HMIm][Cl]> [BMIM][FeCl₄]> [BMIM][Cl]. The reaction parameters such as reaction time, temperature, mole ratio of the reactants, and effect of catalyst loading were optimized.The recyclability of these bifunctional catalysts was also tested and found to be intact for three recycles.

中文翻译：

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在无溶剂条件下使用双功能离子液体催化剂将HMF和生物质衍生的酸升级为HMF酯

近年来，诸如5-羟甲基糠醛（HMF）和乙酰丙酸（LA）的生物质衍生化合物的催化转化为增值化合物引起了极大的兴趣。在这项研究中，我们报告了使用实验室合成的双功能离子液体（IL）催化剂在无溶剂条件下将HMF催化升级为HMF乙酰丙酸酯和HMF酯。使用¹ H NMR和¹³ H表征合成的IL13 C NMR光谱。进行了吡啶傅里叶变换红外光谱（FT-IR）研究，以详细了解Brønsted和Lewis酸度特征。在75至120°C的温度范围内，在5 h反应时间下，分别使用150 mg IL催化剂和4Å分子筛（LA与HMF的摩尔比为5），在HMF转化为HMF乙酰丙酸酯的过程中测试了这些IL的催化活性。 ：1。发现强双酸催化剂[SMIM] [FeCl ₄ ]表现出最高的催化活性，具有97.0％的HMF转化率和78.1％的HMF悬浮剂收率。催化活性依次降低：[SMIM] [FeCl ₄ ]> [BSO ₃ HMIm] [FeCl ₄ ]> [SMIM] [Cl]> [BSO ₃ HMIm] [Cl]> [BMIM] [FeCl ₄]> [BMIM] [Cl]。优化了反应时间，温度，反应物的摩尔比和催化剂负载的影响等反应参数，并测试了这些双功能催化剂的可回收性，发现三个循环均完好无损。