title: Theoretical Insight into the Conversion Mechanism of Glucose to Fructose Catalyzed by CrCl2in Imidazolium Chlorine Ionic Liquids.
abstract: To better understand the efficient transformation of glucose to fructose catalyzed by chromium chlorides in imidazolium-based ionic liquids (ILs), density functional theory calculations have been carried out on a model system which describes the catalytic reaction by CrCl2in 1,3-dimethylimidazolium chlorine (MMImCl) ionic liquid (IL). The reaction is shown to involve three fundamental processes: ring opening, 1,2-H migration, and ring closure. The reaction is calculated to exergonic by 3.8 kcal/mol with an overall barrier of 37.1 kcal/mol. Throughout all elementary steps, both CrCl2and MMImCl are found to play substantial roles. The Cr center, as a Lewis acid, coordinates to two hydroxyl group oxygen atoms of glucose to bidentally rivet the substrate, and the imidazolium cation plays a dual role of proton shuttle and H-bond donor due to its intrinsic acidic property, while the Cl-anion is identified as a Bronsted/Lewis base and also a H-bond acceptor. Our present calculations emphasize that in the rate-determining step the 1,2-H migration concertedly occurs with the deprotonation of O2-H hydroxyl group, which is in nature different from the stepwise mechanism proposed in the early literature. The present results provide a molecule-level understanding for the isomerization mechanism of glucose to fructose catalyzed by chromium chlorides in imidazolium chlorine ILs.
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University , Jinan 250100, P. R. China.
authors.forename: Yaru
authors.identifier: 0000-0002-9025-9360
authors.initials: Y
authors.lastname: Jing
authors.affiliation: Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University , Wuhan 430070, P. R. China.
authors.forename: Jun
authors.identifier: 0000-0002-6692-1828
authors.initials: J
authors.lastname: Gao
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University , Jinan 250100, P. R. China.
authors.forename: Chengbu
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Lab of Colloid and Interface Chemistry, Ministry of Education, Institute of Theoretical Chemistry, Shandong University , Jinan 250100, P. R. China.
authors.forename: Dongju
authors.initials: D
authors.lastname: Zhang
mesh_terms: D002384:Catalysis; D002712:Chlorides / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry*; D005632:Fructose / Q000138:chemical synthesis* / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: C516814:1,3-dimethylimidazolium; D002712:Chlorides; D017608:Chromium Compounds; D007093:Imidazoles; D052578:Ionic Liquids; D005632:Fructose; D005947:Glucose; C022990:chromic chloride