This laboratory module focuses on aqueous organometallic chemistry where a terminal alkyne (2-methyl-3-butyne-2-ol) is coupled with 4-hydroxy-3-iodo-acetophenone in a reaction catalyzed by a palladium complex resulting in the synthesis of a benzofuran product. Traditional palladium-catalyzed alkyne coupling addition methods, involving deprotonated alkynes, are carried out in organic solvent with the careful exclusion of water. The use of metal-catalyzed reactions in water considerably reduces the hazards and environmental impact associated with traditional reactions because the catalyzed reactions can be conducted under mild conditions and they eliminate or reduce the use and disposal of organic solvents.
This greener synthesis is usually carried out over the course of two lab periods. During the first session, students measure out reagents and set up the reaction and during the second session, students isolate, purify, and characterize the product. The link to the laboratory procedures includes pre- and -post lab questions.
Summary prepared May 2005 by Julie A. Haack, Department of Chemistry at the University of Oregon.
Gilbertson, R.; Doxsee, K. M.; Succaw, G.; Huffman, L. M.; Hutchison, J. E. Palladium-Catalyzed Alkyne Coupling/Intramolecular Alkyne Addition: Synthesis of a Benzofuran Product Greener Approaches to Undergraduate Chemistry Experiments, Print Kirchhoff, M., Ryan, M., Eds.; American Chemical Society: Washington D.C., 2002; pp 4-7.