Kinetics of Oxidation of 2,6-Dimethylphenol (DMP) Using Novel μ-Carbonato [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] Complexes
Kinetics of Oxidation of 2,6-Dimethylphenol (DMP) Using Novel μ-Carbonato [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] Complexes作者机构：Chemistry Department Faculty of Science Alexandria University Alexandria Egypt Chemistry Department Faculty of Science University of Jeddah Jeddah KSA
出 版 物：《Open Journal of Inorganic Chemistry》 (无机化学期刊（英文）)
年 卷 期：2016年第6卷第3期
页 面：183-194页
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学]
主 题：Catalysts Kinetics Thermodynamic Copper Complexes
摘 要：This paper reports the kinetics of the oxidation of 2,6-dimethylphenol (DMP) to get 3,3’,5,5’-tetra- methyl-4,4’-diphenoquinone (DPQ) using novel oxidative coupling complexes [(Pip)4nCu4X4-(CO3)2] (n = 1 or 2, X = Cl or Br, Pip = piperidine). The new prepared tetranuclear complexes were characterized using cryoscopic measurements, electronic spectra, FTIR, EPR and cyclic voltammetry techniques. These complexes are catalytically active. The proposed mechanism of the catalytic oxidative coupling can be illustrated as a pre-equilibrium, K, between the catalyst and DMP to form a complex intermediate which is converted to activated complex through the rate determining step, k2, to form the final product. The inverse of the observed rate constants kobsd versus 1/[DMP]2 gives a straight line with intercept. From the slope and the intercept, both K and k2 are obtained. At different temperatures, thermodynamic and kinetic parameters are evaluated. It is worth to mention that, the dependence of kobsd on [DMP]2 indicates that the coordination number for every copper center in both n = 1 or 2 in [(Pip)4nCu4X4(CO3)2] is equal to six. Therefore, carbonato bridging centers in n = 1 acts as a tridentate ligand, while for n = 2 acts as a bidentate ligand.
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