Investigating reaction mechanisms of base-catalyzed isomerization of aldoses into ketoses for developing efficient catalytic processes

醛糖异构化为酮糖是工业上重要的反应。它产生酮基-β-内酰胺，其在食品工业、药物制造、手性有机化合物的合成以及潜在的生物燃料生产中具有很高的需求。目前的酮糖工业生产依赖于酶法，而化学催化方法相对于生物技术生产具有许多优势。例如，化学催化剂成本较低，对原料纯度要求不高。此外，化学催化剂的热稳定性通常优于酶的热稳定性，这使得能够在更高温度下操作，对反应速率和时空产率产生积极影响。考虑到催化剂分离和再循环的容易性，使用固体催化剂是特别有益的。目前的项目重点是研究用于醛糖异构化为酮糖的碱催化剂，最终目标是为这些过程设计高效的化学催化剂。尽管在碱性催化剂上的异构化反应已被人们了解了很长时间，但对该反应的分子机理仍知之甚少。同时，对异构化反应（以及副反应）的动力学和机理的深入了解将有助于高效催化剂的知识驱动开发。在本项目中，将研究葡萄糖异构化为果糖的反应，以了解取决于可溶性和固体催化剂性质的反应动力学和机理。研究了不同结构的其他醛糖的异构化反应，得到了反应效率与醛糖结构的关系。最后，将讨论固体碱性催化剂在反应条件下的稳定性。研究中揭示的相关性将为醛糖异构化为酮糖的催化剂设计和催化过程提供基本的理解。

Isomerization of aldoses into ketoses presents an industrially important reaction. It gives rise to keto-saccharides which are in high demand in food industry, manufacture of pharmaceuticals, synthesis of chiral organic compounds, and potentially for production of biofuels. Current industrial manufactures of ketoses rely on enzymatic processes, whereas chemo-catalytic methods present a number of advantages over biotechnological production. For example, the chemo-catalysts are of lower cost and less demanding to purity of feed. Moreover, thermostability of chemical catalysts typically excels the thermostability of enzymes, which enables operations at higher temperatures with a positive effect on the reaction rates and space-time-yields. Utilization of solid catalysts is especially beneficial considering ease of the catalyst separation and recycling. The current project focuses on investigating the base catalysts for isomerization of aldoses into ketoses with the ultimate goal to elaborate efficient tailor-made chemo-catalysts for these processes. Even though the isomerization over basic catalysts has been known for a long time, a molecular mechanism of this reaction is still poorly understood. At the same time, insight into the kinetics and mechanism of the isomerization (and of side reactions) should facilitate a knowledge-driven development of efficient catalysts.In this project the isomerization of glucose into fructose will be investigated in order to comprehend the kinetics and mechanism of the reaction depending on the nature of soluble and solid catalysts. The isomerization of other aldoses with various structures will be studied; and the dependence of the reaction efficiency on the structure of aldose will be obtained. Finally, stability of solid basic catalysts under the reaction conditions will be addressed. The correlations revealed in the study will provide fundamental understanding for a design of catalysts and catalytic processes for isomerization of aldoses into ketoses.