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Updated: May 16, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
The benzylidenecarbene-phenylacetylene rearrangement: an experimental and computational study
Kathryn A Moore1, Jesus S Vidaurri-Martinez, Dasan M Thamattoor
1Department of Chemistry, Colby College, Waterville, Maine 04901, United States.
Abstract:
Benzylidenecarbene was generated from a new photochemical source, 1-benzylidene-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, in deuterated benzene at ambient temperature. The carbene undergoes a facile rearrangement to phenylacetylene and could not be trapped by olefins. Generation of the carbene bearing a (13)C label at the β-carbon produced phenylacetylene in which the label was found exclusively at the carbon adjacent to the phenyl ring. This overwhelming preference for H shift is consistent with B3LYP and CCSD(T) calculations. The label distribution observed in this work, however, contrasts previously reported high-temperature flash vacuum pyrolysis results where the interconversion of carbene and alkyne leads to the scrambling of labels over both alkynyl (sp) carbons.
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