Related Experiment Video
Updated: Apr 15, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Polar Effects Control the Gas-phase Reactivity of Charged para-Benzyne Analogs
Ashley M Wittrig1, Enada F Archibold1, Huaming Sheng1
1Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907 (USA).
Abstract:
The gas-phase reactivity of charged para-benzynes is entirely unexplored as they and/or their precursors tend to undergo ring-opening upon their generation. We report here a gas-phase reactivity study of two such benzynes, the 2,5-didehydropyridinium and 5,8-didehydroisoquinolinium cations, generated in a modified dual-linear quadrupole ion trap (DLQIT) mass spectrometer. Both biradicals were found to form diagnostic products with organic molecules, indicating the presence of two radical sites. As opposed to earlier predictions that the singlet-triplet (S-T) splitting controls the radical reactivity of such species, the 2,5-didehydropyridinium cation reacts much faster in spite of its larger S-T splitting. Calculated vertical electron affinities of the radical sites of the para-benzynes, a parameter related to the polarity of the transition states of their reactions, appears to be the most important reactivity controlling factor.
Related Concept Videos
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Directing and Steric Effects in Disubstituted Benzene Derivatives
Reactions at the Benzylic Position: Halogenation
Nucleophilic Aromatic Substitution: Elimination–Addition
Directing Effect of Substituents: ortho–para-Directing Groups
Directing Effect of Substituents: meta-Directing Groups

