Question

This is a question from my 11th grade textbook, why does the alkylation of benzene with 1-chloropropane gives 2-propyl benzene and not 1-propylbenzene?

Answer 1

This I think is an example of Friedel Craft alkylation......

Explanation:

And this usually occurs in the presence of a strong Lewis acid such as `AlCl_3`.

i.e. `H_3C-CH_2CH_2Cl + AlCl_3 rarr H_3C-CH_2CH_2^+ + AlCl_4^(-)`

And, formally, we gots a primary carbocation....

`H_3C-CH_2CH_2^+` WHICH MAY undergo sigmatropic reaction to give the more stable secondary carbocation....i.e.

`H_3C-CH_2CH_2^+ rarr H_3C-stackrel(+)CHCH_3`

And the `2^@` carbocation may be the reactive intermediate in the alkylation.

Are you happy with this?