Why m-xylene is more basic than o- and p-xylene in tetrafluoroboric acid? [closed]








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According to me, the more stable sigma complex should be ortho and para xylene as it stabilizes the positive charge through hyperconjugation but in the book the order is meta xylene is more stable than ortho para xylene. Why is hyperconjugation destabilizing in this case?


Source:
KS Verma Organic Chemistry for JEE Advanced




What stabilizes the carbocation is when the methyl groups are ortho/para *to the protonation site.* (The protonation site is where the proton actually adds to the hydrocarbon molecule.) Getting both methyl groups into these favored positions requires them to be meta *to each other*. So the most stable cation isomers are derived from meta-xylene.


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