Baeyer-Villiger Oxidation of Cyclic Ketones Catalyzed by Amino Acid Ionic Liquids
- PDF / 745,955 Bytes
- 5 Pages / 595.32 x 841.92 pts (A4) Page_size
- 37 Downloads / 193 Views
doi: 10.1007/s40242-019-9186-z
Baeyer-Villiger Oxidation of Cyclic Ketones Catalyzed by Amino Acid Ionic Liquids YU Fengli1*, CHI Yujie1, GAO Chong1, CHEN Ruirui2, XIE Congxia1 and YU Shitao2* 1. State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China; 2. College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China Abstract A series of amino-acid-based ionic liquids was synthesized via one-step protonation of the corresponding L-amino acid by utilizing an array of proton sources. The catalytic activity of the amino-acid-based ionic liquids for the Baeyer-Villiger oxidation of cyclic ketones was investigated using cyclopentanone as a model cycloketone. The proline-based ionic liquid [ProH]CF3SO3 was shown to exhibit the best catalytic activity. The reaction condition was optimized to give the following reagent ratio of n(cyclopentanone):n(catalyst):n(H2O2)=1:0.06:4, 60 °C and 6 h. Under the optimum conditions, the conversion of cyclopentanone was 96.57% and the selectivity for δ-valerolactone was 73.01%. The catalytic activity was shown to be constant after 4 cycles. A simple treatment was allowed for the recover and the reuse of [ProH]CF3SO3. The successful utilization of [ProH]CF3SO3 to catalyze a host of cyclic ketones via Baeyer-Villiger oxidation clearly demonstrated the capacity of [ProH]CF 3SO3 to tolerate variation in the substrate. Keywords Amino acid ionic liquid; Baeyer-Villiger oxidation; Cyclic ketone; Lactone
1
Introduction
Lactone is an important organic intermediate for the synthesis of commercially valuable products including polymers, synthetic spices, bactericides, and plant growth regulators[1—3]. In particular, polylactone prepared via the ring-opening polymerization of lactone is extensively used in the generation of materials for medical, environmental and food packaging applications[4]. First reported in 1899, Baeyer-Villiger oxidation of cyclic ketones has become one of the most important synthetic routes to lactone. This, in part, is due to the controllable functional group migration, selective carbonyl oxidation, and stereochemistry retention upon product formation[5—7]. The industrial production of lactone via Baeyer-Villiger oxidation currently utilizes peroxy acid oxidants such as m-chloroperbenzoic acid or potassium monopersulfate[8]. However, the uses of such oxidants present substantial disadvantages including low security, equipment corrosion, and difficult product recovery. The utilization of more processfriendly oxidants for Baeyer-Villiger oxidation including hydrogen peroxide(H2O2) and molecular oxygen(O2) is of current interest[9—11]. Recently, traditional peroxy-based oxidants have been extensively replaced with more economical and environmentally benign H2O2(by-product is H2O). However, due to the lower oxidation potential of H2O2, the catalyst is usually required to promote oxidation via carbonyl and or
H2
Data Loading...
