A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C=O Bonds
A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C=O Bonds
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DOI：
10.1021/jacs.5b04349
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发表时间：
2015-07-01
影响因子：
15
通讯作者：
Kempe, Rhett
中科院分区：
文献类型：
--
作者：
Roesler, Sina;Obenauf, Johannes;Kempe, Rhett
用地球上丰富的廉价金属如Co替代高价贵金属如Ir、Ru、Rh、Pd和Pt是（均相）催化中有吸引力的目标。仅描述了显示有效C=O键氢化速率的Co催化剂的两个实例。在这里，我们报告了一种新型的，易于合成的Co催化剂家族。催化剂活化通过将2当量的金属碱加入到二氯化钴预催化剂中来进行。醛和酮的不同类型（二烷基，芳基-烷基，二芳基）的定量氢化在温和的条件下部分与催化剂负载低至0.25摩尔%。最活跃的Co催化剂与由相同的配体稳定的Ir催化剂的比较表明Co的优越性。已观察到C=C键的存在下，对C=O键的独特选择性。该选择性与现有Co催化剂的选择性相反，并且由于羟基在C=C键氢化中的直接影响而令人惊讶。
The substitution of high-price noble metals such as Ir, Ru, Rh, Pd, and Pt by earth-abundant, inexpensive metals like Co is an attractive goal in (homogeneous) catalysis. Only two examples of Co catalysts, showing efficient C=O bond hydrogenation rates, are described. Here, we report on a novel, easy-to-synthesize Co catalyst family. Catalyst activation takes place via addition of 2 equiv of a metal base to the cobalt dichlorido precatalysts. Aldehydes and ketones of different types (dialkyl, aryl-alkyl, diaryl) are hydrogenated quantitatively under mild conditions partially with catalyst loadings as low as 0.25 mol%. A comparison of the most active Co catalyst with an Ir catalyst stabilized by the same ligand indicates the superiority of Co. Unique selectivity toward C=O bonds in the presence of C=C bonds has been observed. This selectivity is opposite to that of existing Co catalysts and surprising because of the directing influence of a hydroxyl group in C=C bond hydrogenation.