The reduction of organic halides with tributyltin hydride in the presence of a catalytic amount of triethylborane has been studied. (1) Alkyliodides and alkyl bromides reacted easily with tin hydride at −78°C to give the corresponding hydrocarbons, while alkyl chlorides were sluggish to react and recovered unchanged. (2) The reduction of alkenyl halides such as 1-deuterio-1-iodo-1-dodecene and 1-
Rhodium-catalyzed hydrosilylation of alkynes in an aqueous micellar system has been developed. A combination of [RhCl(nbd)](2) and bis(diphenylphosphino)propane (dppp) effects (E)-selective hydrosilylation in the presence of sodium dodecyl sulfate (SDS) in water. The (E)selectivity strongly indicates the formation of a cationic rhodium species via dissociation of the Rh-Cl bond by the action of anionic micelles. The addition of sodium iodide provided (Z)-alkenylsilanes predominantly.
Well-Defined Noble Metal Single Sites in Zeolites as an Alternative to Catalysis by Insoluble Metal Salts
作者:Paula Rubio-Marqués、Miguel A. Rivero-Crespo、Antonio Leyva-Pérez、Avelino Corma
DOI:10.1021/jacs.5b07304
日期:2015.9.16
that the resting insoluble metal is catalytically useless. To circumvent this waste of precious metal and follow a rational design, we generate here well-dispersed Pt(II) and Pd(II) single sites on zeolite Y, with an exquisite control of the Lewis acidity, to catalyze different hydroaddition reactions to alkynes and alkenes with up to 10(4) catalytic cycles (at least 2 orders of magnitude superior to
聚合形式的不溶性贵金属氯化物(即 PtCl2、PdCl2、AuCl、RhCl3)通常用作溶液中大量有机反应的催化剂。在这里,我们表明只有这些贵金属氯化物的少量可溶部分(通常为 5-30%)对炔烃和烯烃的加氢胺化、加氢烷氧基化、氢化硅烷化和环异构化具有催化活性,而其余的不溶性金属在催化上是无用的。为了避免这种贵金属的浪费并遵循合理的设计,我们在沸石 Y 上生成了分散良好的 Pt(II) 和 Pd(II) 单点,并巧妙地控制了路易斯酸度,