Heterogeneous Copper Catalysts
BACKGROUND: The development of effective asymmetric reactions that enable the enantioselective formation of one chiral center over another continues to be an important area of research. A second important area of research relates to the development of water-soluble organometallic catalysts. Conventionally, catalytically active organometallic complexes have been applied as homogeneous catalysts in solution in the organic reaction phase. Difficulties associated with recovery of the homogeneous catalysts from the reactants and products diminish the utility of these homogeneous catalysts, especially when the cost of the catalyst is high or where there is the need to isolate the reaction products in high purity.
DESCRIPTION: Researchers at the University of California, Santa Barbara have developed a simple, general, inexpensive and efficient heterogeneous copper catalyst. The catalyst is very useful for, among other things, “click” cycloadditions. The researchers used an ultrasound technique to enhance the level of adsorption of copper nanoparticles onto a solid support, which provides a surprisingly high degree of copper immobilization. The ultrasound method can create a wide range of immobilized copper contents. Furthermore, the catalyst appears to be unaffected by exposure to air, suggesting a substantial shelf life. Reactions can be carried out in the absence of additives, and external ligands known to accelerate click reactions are not needed.
ADVANTAGES: The advantages of this catalyst include:
* heterogeneous reactions at normal temperatures
* enhanced levels of copper adsorption onto solid support
* reduced copper contamination of products and negligible leeching of copper into solution
* improved solubility
* good shelf life
* quick reaction time
* high yields
* can be recycled with good selectivity
This technology is available for licensing. Patent pending.
Patent Application Number: 20060165580
* "Heterogeneous Copper-in-Charcoal-Catalyzed Click Chemistry" B. Lipshutz* and B. Taft, Angewandte Chemie - October 2006
PATENT STATUS: US Publication No. 20060165580 published July 27, 2006
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