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Oxidative Coupling of Alkynes: The Glaser-Eglinton-Hay Coupling
Author Contact: hutch@uoregon.edu
Summary
The Glaser-Eglinton-Hay reaction has been used to synthesize a number of fungal antibiotics and is important for carbon-carbon bond formation via the oxidative coupling of alkynes. This laboratory exercise illustrates the oxidative coupling of 1-ethynylcyclohexanol in the presence of cuprous chloride, tetramethylethylenediamine and air. Typically, pyridine has been used as a solvent in this type of reaction, but a greener solvent, 2-propanol, is used in this procedure.
A complex mechanism has been proposed for this copper catalyzed coupling reaction. The acetylide, formed by deprotonation of the terminal alkyne, reacts with the cuprous chloride to produce a copper (Cu+1) acetylide complex. Air is bubbled through the reaction solution to oxidize Cu+1 to Cu+2. The Cu+2 is then reduced to Cu+1, resulting in the formation of the alkyne coupling product. The link to the laboratory procedure includes post-lab questions.
Summary prepared July 2005 by Christine K. F. Hermann, Department of Chemistry and Physics at Radford University.
Source
Doxsee, K. M.; Hutchison, J. E. Green Organic Chemistry - Strategies, Tools, and Laboratory Experiments, Print 2004; pp 142-151.
Category Descriptors
- Chemistry Concepts
- Alkynes
- Catalysis
- Oxidation/Reduction Chemistry
- Laboratory Techniques
- Assembly of Reaction Apparatus
- Decolorization
- IR Spectroscopy
- Measuring Mass and Volume
- Melting Points and Melting Ranges
- Recrystallization
- Rotary Evaporation
- Thin-layer Chromatography
- Vacuum Filtration
- Green Chemistry Principles
- Design Less Hazardous Chemical Syntheses
- Increase Energy Efficiency
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- Use Safer Solvents/Reaction Conditions
- Chemistry Subdiscipline
- Organic Chemistry
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