Controlling Reaction Routes in Noble-Metal-Catalyzed Conversion of Aryl Ethers.
Controlling Reaction Routes in Noble-Metal-Catalyzed Conversion of Aryl Ethers.
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DOI：
10.1002/anie.202203172
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发表时间：
2022-07-25
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芳醚在液相中的氢解和水解是从可再生原料获得官能化环状化合物的重要反应。在负载型贵金属上，氢解反应是通过氢加成到芳环上，然后C-O键断裂而引发的。在水中，水解和氢解通过在水或氢插入之前芳环的部分氢化进行。这些机制对于所研究的金属是常见的，但是在十氢萘和水中对氢解的选择性以Pd<Rh<Ir<Ru <Pt的顺序增加;在水中对水解的选择性观察到相反的情况。氢解选择性与氢吸附的吉布斯自由能相关。氢解具有最高的标准活化自由能和对H2压力的弱依赖性，因此，通过提高温度和降低H2压力使氢解的选择性最大化。在水和碱性条件下，对C−O键断裂的选择性达到> 95%。芳基醚的氢解和水解机理对于所研究的金属是共同的。氢解的选择性随着Pd<Rh<Ir<Ru <Pt在十氢萘和水中增加;对于在水中的水解观察到相反的趋势。氢解选择性与H2吸附的吉布斯自由能相关。通过升高温度和降低H2压力，C-O键断裂的选择性最大化。
Hydrogenolysis and hydrolysis of aryl ethers in the liquid phase are important reactions for accessing functionalized cyclic compounds from renewable feedstocks. On supported noble metals, hydrogenolysis is initiated by a hydrogen addition to the aromatic ring followed by C−O bond cleavage. In water, hydrolysis and hydrogenolysis proceed by partial hydrogenation of the aromatic ring prior to water or hydrogen insertion. The mechanisms are common for the studied metals, but the selectivity to hydrogenolysis increases in the order Pd<Rh<Ir<Ru≈Pt in decalin and water; the inverse was observed for the selectivity to hydrolysis in water. Hydrogenolysis selectivity correlates with the Gibbs free energy of hydrogen adsorption. Hydrogenolysis has the highest standard free energy of activation and a weak dependence on H2 pressure, thus, the selectivity to hydrogenolysis is maximized by increasing temperature and decreasing H2 pressure. Selectivity to C−O bond cleavage reaches >95 % in water and alkaline conditions. The mechanisms of hydrogenolysis and hydrolysis of aryl ethers are common for the studied metals. The selectivity to hydrogenolysis increases as Pd<Rh<Ir<Ru≈Pt in decalin and water; the inverse trend is observed for hydrolysis in water. The hydrogenolysis selectivity correlates with the Gibbs free energy of H2 adsorption. The selectivity to C−O bond cleavage is maximized by increasing temperature and decreasing H2 pressure.