Reactivity of Metal Catalysts in Glucose–Fructose Conversion. Issue 38 (26th August 2014)

• Record Type: Journal Article
• Authors: Loerbroks, Claudia; van Rijn, Jeaphianne; Ruby, Marc‐Philipp; Tong, Qiong; Schüth, Ferdi; Thiel, Walter
• Is Part Of: Chemistry. Volume 20:Issue 38(2014)
• Page Start: 12298
• Page End: 12309
• Publication Date: 2014-08-26
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402437
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A joint experimental and computational study on the glucose–fructose conversion in water is reported. The reactivity of different metal catalysts (CrCl₃, AlCl₃, CuCl₂, FeCl₃, and MgCl₂) was analyzed. Experimentally, CrCl₃ and AlCl₃ achieved the best glucose conversion rates, CuCl₂ and FeCl₃ were only mediocre catalysts, and MgCl₂ 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 Brønsted and Lewis acidity (p<italic>K</italic>_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.</p> </abstract>