Degenerate rearrangements of 1H- and L-CHLORO-(1,2),(3,4),(5,6)-tripropanobenzenonium carbocations: Unexpected differences in the behavior of the migrants

Conclusions

• 1. Dissolution of (1,2),(3,4),(5,6)-tripropanobenzene in HSO₃r-SbF₅-SO₂FCl generated the 1H-(1,2),(3,4),(5,6)-tripropanobenzenonium ion, which is converted by the action of Cl₂ to the 1-chloro-(1,2),(3,4),(5,6)-tripropanobenzenonium cation, NMR spectroscopy indicates that these ions undergo a degenerate rearrangement by 1,2-shift of the H and Cl atoms, respectively, at approximately the same rate to C₂ and C⁶.

• 2. The experimental value of ΔG^≠ of the 1,2-chlorine shift in the chlorosubstituted cation is close to that expected on the basis for the reported dependence of ΔG^≠ _Cl on δC⁺, while the ΔG^≠ value for the unsubstituted ion is significantly lower than that expected. This is probably a consequence of a difference in the sensitivity of the σ- and n-type orbitals (H and Cl atoms, respectively) to the effect of orbital orientation.