Efficient Metal-Free Catalytic Reaction Pathway for Selective Oxidation of Substituted Phenols

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• 作者：Yangming Lin ; Bo Li ; Zhenbao Feng ; Yoong Ahm Kim ; Morinobu Endo ; Dang Sheng Su
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：October 2, 2015
• 年：2015
• 卷：5
• 期：10
• 页码：5921-5926
• 全文大小：369K
• ISSN：2155-5435

文摘

Selective oxidation of substituted phenols to p-benzoquinones is known to be inefficient because of the competing C鈥揙 coupling reaction caused by phenoxy radicals. The poor stability of conventional metal-based catalysts represents another bottleneck for industrial application. Here, we describe a metal-free reaction pathway in which onion-like carbon (OLC) as a low-cost catalyst exhibits excellent catalytic activity and stability in the selective oxidation of mono-, di- and trisubstituted phenols to their corresponding p-benzoquinones, even better than the reported metal-based catalysts (e.g., yield, stability) and industrial catalysts for particular substrates. Together with XPS, Raman, DFT calculations, and a series of comparative experiments, we demonstrate that the zigzag configuration as a type of carbon defects may play a crucial role in these reactions by stabilizing the intermediate phenoxy radicals.