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Revision as of 15:05, 5 July 2009 by Rifleman 82 (talk | contribs) (start)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Palladium compounds are used as a catalyst in many coupling reactions, usually as a homogenous catalyst. Examples include:
- Heck reaction between alkenes and aryl halides
- Suzuki reaction between aryl halides and boronic acids
- Stille reaction between an orgnaohalides and organotin compounds
- Sonogashira coupling between aryl halides and alkynes, with copper(I) iodide as a co-catalyst
- Negishi coupling between an organohalide and an organozinc compound
Typical palladium catalysts used include the following compounds:
- palladium acetate
- tetrakis(triphenylphosphine)palladium(0)
- bis(triphenylphosphine)palladium(II) dichloride
- 1,1'-Bis(diphenylphosphino)ferrocene-palladium(II) dichloride
Unoptimized reactions typically use 10-15 mol% of palladium; where optimized, catalyst loadings can be on the order of 0.1 mol % or below.
With these reactions becoming ubiquitous, there has been interest in better techniques for removing the palladium catalyst. Metal scavenger columns such as QuadruPure and ISOLUTE promise more efficient separation than ordinary column chromatography.
References
- http://www.sigmaaldrich.com/chemistry/drug-discovery/medicinal-chemistry/quadrapure.html
- http://www.biotage.com/DynPage.aspx?id=36161