TRAPPING CARBONIUM IONS IN SBF5-HSO3F

Butyl, amyl, and hexyl cations have been generated by the solvolysis of alkyl halides in 2 M SbF5-HSO3F solutions and trapped by hydride transfer from methylcyclopentane both before and after reaching an equilibrium distribution of cations. Tertiary cations predominate at equilibrium in these systems. Under kinetic control tertiary ions may be trapped after little rearrangement but secondary and primary cations show increasing tendencies to isomerize. The data suggest that simple methyl group migrations occur via protonated cyclopropane intermediates rather than by direct methide shifts in the interconversion of methylpentyl and methylbutyl cations. © 1969, American Chemical Society. All rights reserved.