Hydrogen-free ring hydrogenation of phenol to cyclohexanol over a rhodium-loaded titanium(IV) oxide photocatalyst
Hydrogen-free ring hydrogenation of phenol to cyclohexanol over a rhodium-loaded titanium(IV) oxide photocatalyst
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DOI：
10.1016/j.apcata.2019.04.001
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
A. Kinoshita;Kousuke Nakanishi;R. Yagi;A. Tanaka;K. Hashimoto;H. Kominami
中科院分区：
文献类型：
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作者：
A. Kinoshita;Kousuke Nakanishi;R. Yagi;A. Tanaka;K. Hashimoto;H. Kominami
由于光催化反应几乎符合绿色化学的概念，利用光催化剂进行物质转化最近引起了有机化学、物理化学和材料化学领域研究人员的关注。我们研究了在不使用氢气的情况下，在负载金属的氧化钛 (TiO2) 光催化剂上苯酚的光诱导环氢化，并在此报告了各种参数（包括 TiO2 上负载的金属助催化剂的类型和数量以及溶剂和空穴清除剂的种类）对环氢化的影响。我们发现Rh助催化剂、水和草酸的组合产生了最高的环己醇产率。详细分析表明，苯酚首先通过环己烯醇的酮-烯醇互变异构作用氢化为环己酮，然后环己酮氢化为环己醇，并且苯酚在Rh-TiO2上的吸附是环氢化的一个重要因素。
Since photocatalytic reactions are almost consistent with the concept of green chemistry, substance conversion using photocatalysts has recently attracted the attention of researchers in the fields of organic chemistry, physical chemistry and material chemistry. We investigated photoinduced ring hydrogenation of phenol over a metal-loaded titanium(IV) oxide (TiO2) photocatalyst without the use of H2gas and we report here the effects of various parameters, including the type and amount of metal co-catalyst loaded on TiO2and the kinds of solvents and hole scavengers, on the ring hydrogenation. We found that the combination of an Rh co-catalyst, water and oxalic acid resulted in the highest yield of cyclohexanol. Detailed analyses revealed that phenol was first hydrogenated to cyclohexanone via keto-enol tautomerism of cyclohexenol followed by hydrogenation of cyclohexanone to cyclohexanol and that adsorption of phenol onto Rh-TiO2is a factor of great importance for the ring hydrogenation.