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Updated: May 22, 2026
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Solvent polarity effects on carbene/ether-O-ylide equilibria.
Pablo A Hoijemberg1, Robert A Moss, Karsten Krogh-Jespersen
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, USA.
p-Nitrophenylchlorocarbene reversibly formed O-ylides with cyclic ethers like THF and dioxane. Spectroscopic and computational studies confirmed these structures and quantified reaction equilibrium, showing solvent polarity dependence.
Area of Science:
- Organic Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Carbenes are highly reactive intermediates with diverse chemical applications.
- Understanding carbene reactivity with cyclic ethers is crucial for synthetic chemistry.
- O-ylides represent a class of compounds with unique electronic properties.
Purpose of the Study:
- To investigate the reversible reaction between p-nitrophenylchlorocarbene (PNPCC) and cyclic ethers.
- To characterize the resulting O-ylides using spectroscopic and computational methods.
- To determine the influence of solvent polarity on the reaction equilibrium.
Main Methods:
- UV-vis spectroscopy was employed to visualize and quantify O-ylide formation.
- Equilibrium constants (K) were determined spectroscopically.
- Density functional theory (DFT) calculations were performed to model structures, energetics, and spectroscopic properties.
Main Results:
- PNPCC reacted reversibly with tetrahydrofuran (THF), tetrahydropyran (THP), 1,3-dioxane (1,3-D), and 1,4-dioxane (1,4-D) to form stable O-ylides.
- Characteristic UV-vis signatures confirmed the presence of the O-ylides.
- Equilibrium constants demonstrated a clear dependence on solvent polarity, as studied in pentane/1,2-dichloroethane blends.
Conclusions:
- The formation of O-ylides from PNPCC and cyclic ethers is a reversible process.
- Spectroscopic and DFT computational data provide a consistent understanding of the carbene-ether O-ylide system.
- Solvent polarity significantly influences the equilibrium of O-ylide formation.
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