Studies on the oxidation of phenols catalyzed by a copper(II)–Schiff base complex in aqueous solution under mild conditions
✍ Scribed by Xiang-Guang Meng; Jie Zhu; Jie Yan; Jia-Qing Xie; Xing-Ming Kou; Xiao-Fan Kuang; Li-Feng Yu; Xian-Cheng Zeng
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2005
- Tongue
- English
- Weight
- 120 KB
- Volume
- 81
- Category
- Article
- ISSN
- 0268-2575
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✦ Synopsis
Abstract
The catalytic oxidation of phenol with hydrogen peroxide using a synthetic copper(II)–Schiff base complex as catalyst has been investigated in phosphate buffer at pH 7 and 25 °C. In order to further investigate the reaction pathway, the catalytic oxidation of hydroquinone, p‐benzoquinone and catechol were also studied under the same conditions. These reactions were found to be pseudo‐first‐order with respect to the concentration of phenolic substances. The rate constants were also calculated. In the presence of catalyst, the kinetics and the HPLC analysis showed that for the first step phenol was oxidized to hydroquinone and catechol, and the catalyst easily promoted the formation of hydroquinone but not catechol, for the second step the dihydroxybenzenes were further oxidized to benzoquinone, and lastly short‐chain acids, including maleic acid and oxalic acid, were formed. The activity of the catalyst hardly decreased during the whole reaction. Addition of imidazole accelerated the oxidation of phenol. The catalytic decomposition of hydrogen peroxide using this catalyst was also investigated. Copyright © 2005 Society of Chemical Industry