ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Efficient and convenient oxidation of cyclohexene to adipic acid with H2O2 catalyzed by H2WO4 in acidic ionic liquids
Bingtong Wang, Zongbin Zhang, Xinyu Zhang, Shixin Sun, Lin Wu, and Rong Xing
Yancheng Teachers University, Yancheng, China
Abstract: A simple, efficient, and eco-friendly catalytic system for the oxidation of cyclohexene to adipic acid with H2O2 catalyzed by H2WO4 in Brønsted acidic ionic liquids under solvent-free conditions has been developed. Reaction conditions such as the catalysts, the types of anions and cations for Brønsted acidic ionic liquids, reaction temperature, and the amount of hydrogen peroxide, were investigated. Moreover, the Hammett acidity functions (H 0) of Brønsted acidic ionic liquids were determined using UV–visible spectrophotometry. The optimum reaction condition identified was n(H2WO4):n(Brønsted acidic ionic liquids):n(cyclohexene):n(H2O2) = 0.02:0.02:1:4.4, and the yield of adipic acid was 96% under the reaction scale of 10 mmol. The catalytic system can be easily recovered and reused for four reaction runs without significant loss of catalytic activity. Simple operation of the catalyst system and avoidance of the emission of nitrous oxide are the benefits of this work.
Keywords: Acidic ionic liquid ; H2WO4 ; Adipic acid ; Solvent-free oxidation
Full paper is available at www.springerlink.com.
Chemical Papers 72 (3) 643–649 (2018)