Question

Heating any of the three isomeric dimethylbenzenes with HF in the presence of BF3 to 80oC leads to the equilibrium mixture shown below. Formulate a mechanism for these isomerizations, starting with 1,2-dimethylbenzene and simply using H+ to represent the acid. Why is the equilibrium concentration of the 1,2-isomer the lowest?

Answer 1

The equilibrium concentration of the 1,2-isomer the lowest due to the steric effects.