Zeolite-Y Encapsulated Metal Picolinato Complexes as Catalyst for Oxidation of Phenol with Hydrogen Peroxide

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• 作者：Kusum K. Bania ; Ramesh C. Deka
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：June 6, 2013
• 年：2013
• 卷：117
• 期：22
• 页码：11663-11678
• 全文大小：744K
• 年卷期：v.117,no.22(June 6, 2013)
• ISSN：1932-7455

文摘

A systematic experimental and density functional theory (DFT) study has been carried out on the selective oxidation of phenol to catechol by bis(picolinato) complexes of cobalt, nickel, and copper prepared in solution and encapsulated in zeolite-Y. The catalytic activities of the homogeneous catalysts and their heterogeneous counterparts are compared under microwave irradiation in the presence of H₂O₂ as mild oxidant. Catechol is obtained selectively in good yield when the catalytic oxidation is carried out using bis(picolinato) Cu(II) complex encapsulated in zeolite-Y. An ultraviolet鈥搗isible (UV鈥搗is) spectrum shows that the increase in the amount of H₂O₂ further oxidizes catechol to benzoquinone. Electron paramagnetic resonance (EPR) and cyclic voltammetry studies reveal the existence of cis 鈫?trans isomerization in case of Cu(II) complex, which has been further substantiated by DFT calculations. A plausible mechanism for the formation of catechol mediated by synthesized complexes has been provided by means of DFT calculations from the energetics involved in the transformations.