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Oxidative coupling of 2,6‐dimethylphenol catalyzed by copper(II) complexes in aqueous solution
Author(s) -
Liu Ying,
Pang QinHui,
Meng XiangGuang,
Liu FuRong,
Li JianMei,
Du Juan,
Hu ChangWei
Publication year - 2010
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.32320
Subject(s) - catalysis , chemistry , copper , aqueous solution , oxidative coupling of methane , ether , kinetics , polymer chemistry , reaction mechanism , tris , medicinal chemistry , inorganic chemistry , organic chemistry , physics , quantum mechanics , biochemistry
The oxidative coupling reaction of 2,6‐dimethylphenol (DMP) with H 2 O 2 catalyzed by four copper(II) complexes was investigated in Tris‐HNO 3 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 k 2 and K m 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 LCu I (OH − )‐ • OOH was suggested as the possible predominant species to oxidize DMP. The CC and CO 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 CO coupling reaction in our catalytic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010