Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA, 99352, USA.
Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4, 85748, Garching, Germany.
Angew Chem Int Ed Engl. 2017 Feb 13;56(8):2110-2114. doi: 10.1002/anie.201611076. Epub 2017 Jan 18.
Metallic palladium surfaces are highly selective in promoting the reductive hydrolysis of aromatic ethers in aqueous phase at relatively mild temperatures and pressures of H . At quantitative conversions, the selectivity to hydrolysis products of PhOR ethers was observed to range from 50 % (R=Ph) to greater than 90 % (R=n-C H , cyclohexyl, and PhCH CH ). By analysis of the evolution of products with and without incorporation of H O, the pathway was concluded to be initiated by palladium metal catalyzed partial hydrogenation of the phenyl group to an enol ether. Water then rapidly adds to the enol ether to form a hemiacetal, which then undergoes elimination to cyclohexanone and phenol/alkanol products. A remarkable feature of the reaction is that the stronger Ph-O bond is cleaved rather than the weaker aliphatic O-R bond.
金属钯表面在水相条件下、温和的温度和氢气压力下，对芳基醚的还原水解具有很高的选择性。在定量转化率下，PhOR 醚的水解产物的选择性范围从 50%（R=Ph）到大于 90%（R=n-C H 、环己基和 PhCH CH ）。通过分析有无 H O 加入时产物的演变，可以得出反应途径是由钯金属催化的苯基部分氢化到烯醇醚引发的。然后水迅速加到烯醇醚中形成半缩醛，然后消除生成环己酮和苯酚/醇产物。该反应的一个显著特点是断裂较强的 Ph-O 键，而不是较弱的脂肪族 O-R 键。
