D. M. Brouwer
Sep 2, 2010
Citations
0
Influential Citations
2
Citations
Journal
Recueil des Travaux Chimiques des Pays-Bas
Abstract
2-Fluoro-, chloro- and bromomesitylenes, and 5-fluoro-, chloro- and bromo-m-xylenes have been found to form stable benzenium ions in HF-SbF5. The cations give well-resolved PMR spectra, from which their structures have been derived. The 2-halomesitylenes are “exclusively” protonated in the unsubstituted ring positions. The 5-halo-m-xylenes give mixtures of two cations, with the captured proton ortho and para to the halogen, respectively, the preference for the para position increasing from Br to Cl to F. 4-Chloro-m-xylene and 2-chloro-p-xylene give “stable” cations, which slowly rearrange to the 5-chloro-m-xylenium ion. Protonation of 2- and 4-bromo-m-xylenes at 0° yields instantaneously the 5-bromo-m-xylenium ion, probably as the result of intermolecular reactions. A novel and facile synthetic route to 5-bromo-m-xylene is described.