文献类型：期刊文献

英文题名：Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

作者：Chen, Chen[1];Yuan, Haiyang[1];Wang, Haifeng[1];Yao, Yefeng[2,3];Ma, Wenbao[1];Chen, Jizhong[1];Hou, Zhenshan[1]

机构：[1]E China Univ Sci & Technol, Res Inst Ind Catalysis, Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]E China Normal Univ, Dept Phys, Shanghai 200062, Peoples R China;[3]E China Normal Univ, Shanghai Key Lab Magnet Resonance, Shanghai 200062, Peoples R China

年份：2016

卷号：6

期号：5

起止页码：3354

外文期刊名：ACS CATALYSIS

收录：;EI(收录号：20162402498884);WOS:【SCI-EXPANDED(收录号:WOS:000375894500075)】；

基金：The authors are grateful for support from the National Natural Science Foundation of China (21174039, 21373082, 21574043, 21574043), National High-tech R&D Program of China (863 Program) (2014AA123400, 2014AA123401), the Innovation Program of Shanghai Municipal Education Commission (15ZZ031), and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：peroxoniobate anion; ionic liquid; epoxidation; allylic alcohols; DFT

摘要：This work reports new kinds of monomeric peroxoniobate anion functionalized ionic liquids (ILs) designated as [A(+)][Nb=O(O-O)(OH)(2)] (A(+) = tetrapropylammonium, tetrabutylammonium, or tetrahexylammonium cation), which have been prepared and characterized by elemental analysis, HRMS, NMR, IR, TGA, etc. With hydrogen peroxide as an oxidant, these ILs exhibited excellent catalytic activity and recyclability in the epoxidation of various allylic alcohols under solvent free and ice bath conditions. Interestingly, subsequent activity tests and catalyst characterization together with first-principles calculations indicated that the parent [Nb=O(O-O)(OH)(2)](-) anion has been oxidized into the anion [Nb(O-O)(2)(OOH)(2)](-) in the presence of H2O2, which constitutes the real catalytically active species during the reaction; this anion has higher activity in comparison to the analogous peroxotungstate anion. Moreover, the epoxidation process of the substrate (allylic alcohol) catalyzed by [Nb(O-O)(2)(OOH)(2)](-) was explored at the atomic level by virtue of DFT (density functional theory) calculations, identifying that it is more favorable to occur through a hydrogen bond mechanism, in which the peroxo group of [Nb(O-O)(2)(OOH)(2)](-) serves as the adsorption site to anchor the substrate OH group by forming a hydrogen bond, while OOH as the active oxygen species attacks the C=C bond in substrates to produce the corresponding epoxide. This is the first example of the highly efficient epoxidation of allylic alcohols using a peroxoniobate anion as a catalyst.