Porous Tin-Organic Frameworks as Selective Epimerization Catalysts in Aqueous Solutions
Porous Tin-Organic Frameworks as Selective Epimerization Catalysts in Aqueous Solutions
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DOI：
10.1021/acscatal.7b00806
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发表时间：
2017-06-01
期刊：
影响因子：
12.9
通讯作者：
Rose, Marcus
中科院分区：
文献类型：
--
作者：
Delidovich, Irina;Hoffmann, Andreas;Rose, Marcus
糖的差向异构化是一种碳效率高的途径，不仅可以生产稀有碳水化合物，还可以扩大未来生物炼制中化学生产的产品范围。工业上可获得的差向异构化催化剂主要限于可溶性Mo（VI）物种以及底物特异性差向异构酶。在这里，我们报告了高活性和选择性的锡有机框架（锡OF）作为固体催化剂的差向异构化的醛糖在C-2位，如葡萄糖转化为甘露糖。该反应通过碳骨架重排进行，即通过C-2/C-3碳键的断裂和C-1/C-3键的形成。部分水解的Ph 3Sn-OH位点被发现是催化活性中心。研究结果表明，锡的刘易斯酸性、锡的自由基和有机连接基的疏水性决定了锡氧自由基对差向异构化反应的高催化活性。
Epimerization of sugars is a carbon-efficient route not only to produce rare carbohydrates but also to extend the product scope for chemical production in future biorefineries. Industrially available catalysts for epimerization are limited mainly to soluble Mo(VI) species as well as substrate-specific epimerases. Here we report highly active and selective tin-organic frameworks (Sn-OF) as solid catalysts for the epimerization of aldoses at the C-2 position, such as the conversion of glucose to mannose. The reaction proceeds via a carbon skeleton rearrangement, that is, through breaking of a C-2/C-3 carbon bond and formation of a C-1/C-3 bond. Partially hydrolyzed Ph3Sn-OH sites were found to be the catalytically active centers. Our results suggest that the high catalytic activity of Sn-OFs for the epimerization is determined by (1) Lewis acidity of tin; (2) free Sn-OH groups; and (3) the high hydrophobicity of organic linkers applied in the aqueous solutions.