Oxidative coupling of 2,6‐dimethylphenol catalyzed by copper(II) complexes in aqueous solution |
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| Authors: | Ying Liu Qin‐Hui Pang Xiang‐Guang Meng Fu‐Rong Liu Jian‐Mei Li Juan Du Chang‐Wei Hu |
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| Affiliation: | 1. Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China;2. College of Information and Control Engineering, Weifang University, Weifang 261061, People's Republic of China |
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| Abstract: | The oxidative coupling reaction of 2,6‐dimethylphenol (DMP) with H2O2 catalyzed by four copper(II) complexes was investigated in Tris‐HNO3 buffer solution at 25°C. The kinetics of formation of diphenoquinone (DPQ, 4‐(3,5‐dimethyl‐4‐oxo‐2,5‐cyclohexadienylidene)‐2,6‐dimethyl‐2,5‐cyclohexadienone) from DMP was studied in detail. The kinetic parameters k2 and Km were obtained in the pH range of 6.0–9.0. The copper(II) complexes exhibited the optimal catalytic activity at around pH 7.0. The pH effect was reasonably explicated by the catalytic kinetic model suggested in this work. The catalytic mechanism was discussed. The deprotonized associated radical LCuI(OH?)‐?OOH was suggested as the possible predominant species to oxidize DMP. The C? C and C? O coupling products were analyzed and the ratio of poly (2,6‐dimethyl‐1,4‐phenylene ether) (PPE) to DPQ was also evaluated. Both in weak acidic (pH < 6.5) and in alkaline aqueous solution (pH > 8) were suitable to the C? O coupling reaction in our catalytic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 |
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| Keywords: | oxidative coupling organometallic catalyst catalysis kinetics PPE |
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