Ytterbium(II) as a mediator in organic electrosynthesis - possibilities and limitations
Ytterbium(II) as a mediator in organic electrosynthesis - possibilities and limitations
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DOI：
10.1016/s0013-4686(02)00844-7
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发表时间：
2003-04-05
影响因子：
6.6
通讯作者：
Pletcher, D
中科院分区：
文献类型：
--
作者：
Andreu, R;Pletcher, D
在几种电极材料上，Yb(III)/Yb(II)在非质子溶剂中的反应动力学很快，Yb(II)的还原能力可以通过溶剂和电解液的选择得到很大程度的改变。当电生Yb(II)以化学计量比存在时，允许1，3-二苯甲酰丙烷的立体选择性还原为环状二醇的顺式异构体。然而，Yb(III)并不是一个直接的‘介体’，因为在Yb(H)还原1，3-二苯甲酰丙烷后，Yb(III)与有机产品结合。使用铝阳极或添加三甲基硅烷都会导致Yb(III)的释放，然后Yb充当催化剂。然而，这些过程导致还原的立体选择性丧失，反应缓慢，因此Yb(III)的再生不会提高电流密度。受催化剂传质的限制，电流密度总是很低。(C)2003爱思唯尔科学有限公司。保留所有权利。
The kinetics of the Yb(III)/Yb(II) couple in aprotic solvents are rapid at several electrode materials and the reducing power of the Yb(II) may be modified substantially by choice of solvent and electrolyte. Electrogenerated Yb(II), when present in stoichiometric amounts, allows the stereoselective reduction of 1,3-dibenzoylpropane to the cis isomer of a cyclic diol. Ytterbium(III) is not, however, a straightforward 'mediator' because, after the reduction of 1,3-dibenzoylpropane by the Yb(H), the Yb(III) is bound to the organic product. Both use of an aluminium anode or addition of trimethylsilylbromide lead to release of the Yb(III); then the ytterbium acts as a catalyst. Such procedures, however, lead to loss in the stereoselectivity of the reduction and the reactions are slow so that the regeneration of the Yb(III) does not enhance the current density. The current density is always low, limited by mass transport of the catalyst. (C) 2003 Elsevier Science Ltd. All rights reserved.