Chemical Research in Chinese Universities ›› 2020, Vol. 36 ›› Issue (5): 865-869.doi: 10.1007/s40242-019-9186-z

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Baeyer-Villiger Oxidation of Cyclic Ketones Catalyzed by Amino Acid Ionic Liquids

YU Fengli1, CHI Yujie1, GAO Chong1, CHEN Ruirui2, XIE Congxia1, YU Shitao2   

  1. 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
  • Received:2019-07-05 Revised:2019-08-19 Online:2020-10-01 Published:2020-10-01
  • Contact: YU Fengli, YU Shitao E-mail:yufliqust@163.com;yushitaoqust@126.com
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21878166), the Taishan Scholar Project of Shandong Province, China(No.ts201511033), the Emphasis Development Plan of Shandong Province, China(Nos.2017GGX70102, 2017GGX40107) and the Open Project of the Chemistry Department in Qingdao University of Science and Technology of China (No.QUSTHX201811).

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℃ 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]CF3SO3 to tolerate variation in the substrate.

Key words: Amino acid ionic liquid, Baeyer-Villiger oxidation, Cyclic ketone, Lactone