Question

What will be the product when C6H6Cl6 is heated with alc. KOH? Please explain the mechanim too.

Answer 1

The reaction will occur if all the `Cl` atoms are in same side ie syn and
the reaction will not occur if the `Cl` atoms are alternate syn and anti. Explanation is given below :-

Explanation:

NOTE :-

`E_2` reaction is Anti-elimination reaction so see in the picture given below :-

`1)` in first case the reaction will occur because the adjacent `Cl` and `H` atoms are Anti, so elimination is possible.

`2)` in the second case the reaction will not occur because the adjacent `Cl` and `H` atoms are Syn so elimination is not possible there in second case.

The reaction of Alkyl halide `(RX)` with Strong base like alc. `KOH` in the presence of heat is Elimination reaction and it follows the `E_2` mechanism and this reaction gives Alkene as the final product along with the corresponding Hydrogen halide `(HX)`.

General `E_2` reaction in the Presence of Heat :-

`RX + alc KOH rarr`Alkene `+ HX`