Related Experiment Video
Updated: Jul 7, 2026

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
Published on: December 16, 2019
Structural and rate studies of the formation of substituted benzynes
Jason C Riggs1, Antonio Ramirez, Matthew E Cremeens
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
Abstract:
The key elimination step for the formation of 3-substituted and 3,6-disubstituted benzynes from 2-haloaryllithiums displays a pronounced solvent-dependent regioselectivity. All 2-haloaryllithiums with electron withdrawing groups in the 6 position are shown by 6Li and 13C NMR spectroscopic studies to be monomers in THF. DFT computational studies implicate trisolvates. Rate studies reveal that LiF eliminates via monomer-based pathways requiring THF dissociation whereas LiCl eliminates via nondissociative pathways. Elimination to form 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity that is traced to competing solvent-dissociative and nondissociative dissociative pathways for the elimination of LiCl and LiF, respectively.
Related Concept Videos
Structure of Benzene: Kekulé Model
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
Electrophilic Aromatic Substitution: Nitration of Benzene
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
NMR Spectroscopy of Benzene Derivatives
Nomenclature of Aromatic Compounds with Multiple Substituents
For disubstituted benzene derivatives, with two groups attached to the benzene ring, three constitutional isomers are possible. For example, consider dimethyl benzene, often called xylene, where the second methyl group can be substituted at the second, third, or fourth carbon. The relative position of the substituents is represented by prefixes ortho, meta, or...

