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首页> 外文期刊>Chemistry: A European journal >Reactivity of Metal Catalysts in Glucose–Fructose Conversion
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Reactivity of Metal Catalysts in Glucose–Fructose Conversion

机译：金属催化剂在葡萄糖-果糖转化中的反应性

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摘要

A joint experimental and computational study on the glucose–fructose conversion in water is reported. The reactivity of different metal catalysts (CrCl_3, AlCl_3, CuCl_2, FeCl_3, and MgCl_2) was analyzed. Experimentally, CrCl_3 and AlCl_3 achieved the best glucose conversion rates, CuCl_2 and FeCl_3 were only mediocre catalysts, and MgCl_2 was inactive. To explain these differences in reactivity, DFT calculations were performed for various metal complexes. The computed mechanism consists of two proton transfers and a hydrogen-atom transfer; the latter was the rate-determining step for all catalysts. The computational results were consistent with the experimental findings and rationalized the observed differences in the behavior of the metal catalysts. To be an efficient catalyst, a metal complex should satisfy the following criteria: moderate Br?nsted and Lewis acidity (pK_a=4–6), coordination with either water or weaker σ donors, energetically low-lying unoccupied orbitals, compact transition-state structures, and the ability for complexation of glucose. Thus, the reactivity of the metal catalysts in water is governed by many factors, not just the Lewis acidity.
机译：报道了联合实验和计算研究水中葡萄糖-果糖的转化。分析了不同金属催化剂（CrCl_3，AlCl_3，CuCl_2，FeCl_3和MgCl_2）的反应性。实验上，CrCl_3和AlCl_3达到了最佳的葡萄糖转化率，CuCl_2和FeCl_3只是中等水平的催化剂，而MgCl_2没有活性。为了解释这些反应性差异，对各种金属络合物进行了DFT计算。计算机理包括两个质子转移和一个氢原子转移。后者是所有催化剂的决定速率的步骤。计算结果与实验结果一致，并使观察到的金属催化剂行为差异合理化。要成为有效的催化剂，金属络合物应满足以下条件：中等布朗斯台德酸度和路易斯酸度（pK_a = 4–6），与水或较弱σ供体的配位，低能的低空轨道，紧凑的过渡态的结构，以及葡萄糖络合的能力。因此，金属催化剂在水中的反应性受许多因素支配，而不仅仅是路易斯酸度。

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