Conversion of I to II :

Options

A. takes place by `S_(N)^(1)`
B. takes place by `S_(N)^(2)`
C. takes place both by `S_(N)^(1)` and `S_(N)^(2)`
D. does not take place

Answer

D

Explanation

In - 1 bromotriptycener,

The bromine atom is found to be virtually inert to nucleophilies. Despite the formal resemblance in the environment ofthe bromine atomin to thatin, they are found to differ in their rate ofreaction under parallel conditions by a factor of `~~ 10^(-23)` : 1 ! This is bacause stabilisation ofthe carbocation in en can occur bydelocalisation ofits charge through the `pi-` orbital systems ofthe three benzene rings, whereas the extremelyrigid structure of (ll) will hold the cation.s emptyorbital (from loss of `Br^(Theta)` but a right angles to these `pi` -orbital systems, thus preventing such delocalisation.