(nBu4N)4W10O32-catalyzed selective oxygenation of cyclohexane by molecular oxygen under visible light irradiation
(nBu4N)4W10O32-catalyzed selective oxygenation of cyclohexane by molecular oxygen under visible light irradiation
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DOI：
10.1016/j.apcatb.2014.08.045
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发表时间：
2015-03
影响因子：
22.1
通讯作者：
Wenfeng Wu;Z. Fu;Senbei Tang;Shuai Zou;X. Wen;Y. Meng;Shu-Jing Sun;Jie Deng;Yachun Liu
中科院分区：
文献类型：
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作者：
Wenfeng Wu;Z. Fu;Senbei Tang;Shuai Zou;X. Wen;Y. Meng;Shu-Jing Sun;Jie Deng;Yachun Liu
开发温和高效的分子氧选择性氧化有机化合物的工艺是合成含氧化合物的关键技术之一。在可见光照射和纯o2气氛下，环己烷在十钨酸四丁基铵（W10O324−）上光氧化生成环己醇和环己酮。W10O324−在纯乙腈（MeCN）中具有良好的光氧化活性，在持续可见光照射12 h下，环己烷转化率为8.1%，环己酮选择性为0.64.3%。值得注意的是，在一些酸性添加剂（如10 M HCl、H2SO4或h3po4水溶液和苯磺酸）的存在下，上述光催化氧化在一定程度上得到了改善，提供了ca。环己烷与ca的转化率为12.4-14.3%。环己酮选择性59.7 ~ 69.4%。在加入适量的水的情况下，酸的促进作用进一步增强，可以提高转化率（16.8 ~ 20.0%），提高环己酮的选择性（68.2 ~ 78.3%）。在W10O324−光催化氧化其他底物如甲苯、乙苯和丁酮时，也观察到这种酸性水溶液促进的效应。这可能是由于酸性水溶液在改善W10O324 -的光氧化还原循环和保持其稳定性方面发挥了重要作用，这一点得到了紫外可见光谱和循环伏安测量的支持。
The development of mild and efficient process for the selective oxygenation of organic compounds by molecular oxygen (O2) can be one of the key technologies for synthesizing oxygenates. Here, the photo-oxygenation of cyclohexane to cyclohexanol and cyclohexanone over tetrabutylammonium decatungstate (W10O324−) was carried out under visible light irradiation and pure O2atmosphere. The W10O324−was found to be active to this photo-oxygenation in a pure acetonitrile (MeCN), which can achieveca.8.1% cyclohexane conversion withca.64.3% selectivity for cyclohexanone under sustained visible light irradiation of 12 h. Notably, the above-described photo-catalysis oxygenation was improved to some extent in the presence of some acidic additives such as10 M HCl, H2SO4, or H3PO4aqueous solution and benzenesulfonic acid, providingca. 12.4–14.3% cyclohexane conversion withca. 59.7–69.4% cyclohexanone selectivity. Moreover, this acid-promoted effect was further magnified in the case of adding a suitable amount of water, which can lead to enhancing conversion (16.8–20.0%) and improving cyclohexanone selectivity (68.2–78.3%). This acidic aqueous solution-promoted effect was also observed upon the W10O324−-photocatalyzed oxygenation of other substrates like toluene, ethylbenzene and butanone. This is likely due to the acidic aqueous solutions playing important roles in improving photo-redox cycling of W10O324−and preserving its stability, as supported by the UV–vis spectra and cyclic voltammetry measurements.