Schmid Julian, Wang Meng, Gutiérrez Oliver Y, Bullock R Morris, Camaioni Donald M, Lercher Johannes A
Institute for Integrated Catalysis, Pacific Northwest National Laboratory (PNNL), P.O. Box 999, Richland, WA 99352, USA.
Department of Chemistry and Catalysis Research Institute, Technische Universität München, Lichtenbergstrasse 4, 85748, Garching, Germany.
Angew Chem Int Ed Engl. 2022 Jul 25;61(30):e202203172. doi: 10.1002/anie.202203172. Epub 2022 Jun 14.
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 H pressure, thus, the selectivity to hydrogenolysis is maximized by increasing temperature and decreasing H pressure. Selectivity to C-O bond cleavage reaches >95 % in water and alkaline conditions.
芳基醚在液相中的氢解和水解是从可再生原料制备功能化环状化合物的重要反应。在负载型贵金属上，氢解反应是通过向芳环上加氢，随后发生C-O键断裂来引发的。在水中，水解和氢解反应是在水或氢插入之前通过芳环的部分氢化进行的。这些机制对于所研究的金属来说是常见的，但在十氢化萘和水中，氢解选择性按Pd<Rh<Ir<Ru≈Pt的顺序增加；而在水中观察到的水解选择性顺序则相反。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，并且对氢气压力的依赖性较弱，因此，通过升高温度和降低氢气压力可使氢解选择性最大化。在水和碱性条件下，C-O键断裂的选择性达到>95%。
