Kinetics of Isomerizations Involving Arenium Ions

After characterizing the rates of the 1,2-shift of hydrogen and different groups it is reasonable to return to isomerizations of substituted benzenium ions. Isomerization of methylated benzenes In HF—SbFj at 25 °C o- and p-xylenes are present as ions (105) and (106) which are further practically completely converted to a conjugate acid of m-xylene, i.e. ion (JOT). 

By conventional kinetic methods, the rate coefficients for the transformation of ions (105) and (106) into ion (107) is determined. Similarly, one can find the rate 

The rate coefficients for most of the mentioned transformations are listed in Table 53 

The data obtained from the degenerate rearrangements of benzenium ions testify that the rate coefficients of intraionic 1,2-hydrogen shifts are usually by several 

Reaction 10 k (s- ) AG kcal/mole Stage of 1,2-CH3-shift 10 kcHj (s- ) AOc h, kcal/mole GcHj kcal/mole 

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