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Updated: Apr 26, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
O-ylide and π-complex formation in reactions of a carbene with dibenzo and monobenzo crown ethers
Pablo A Hoijemberg1, Robert A Moss, David V Feinblum
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , New Brunswick, New Jersey 08903, United States.
Abstract:
Reactions of p-nitrophenylchlorocarbene (PNPCC) with various dibenzo crown ethers produce O-ylides and π-complexes; the reactions can be followed via the spectral signatures of the carbene and the products. The O-ylides form most rapidly, but over time they decay in favor of the more stable π-complexes. Extensive computational studies support and refine appropriate structural and mechanistic conjectures. Reactions of PNPCC with monobenzo crown ethers afford only the spectral signatures of O-ylides; monobenzo π-complexes are either not formed in significant concentrations or are spectroscopically silent.
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