Question

Give reasons for the following: (a) Chlorine is ortho/para directing in electrophilic aromatic substitution reactions, though chlorine is an electron withdrawing group.
(b) Racemic mixture is optically inactive.
(c) Allyl chloride is hydrolysed more readily than n-propyl chloride.

Hint:

- Chlorine is ortho/para directing because of the stabilization of the carbocation through resonance. - Racemic mixtures result in optical inactivity due to the equal amounts of enantiomers canceling each other’s rotation. - Allyl chloride is more readily hydrolyzed than n-propyl chloride due to the resonance stabilization of the allyl carbocation.

Answer 1

(a) Chlorine is ortho/para directing in electrophilic aromatic substitution reactions, though chlorine is an electron withdrawing group.
Chlorine is ortho/para directing in electrophilic aromatic substitution reactions Although chlorine is an electron-withdrawing group through its inductive effect, it acts as an electron-donating group through resonance by donating lone pairs on chlorine to stabilize the intermediate carbocation. This effect is more pronounced at the ortho and para positions relative to the chlorine atom. (b) Racemic mixture is optically inactive.
Racemic mixture is optically inactive A racemic mixture contains two enantiomers in equal proportions. Enantiomers are non-superimposable mirror images of each other, and in a racemic mixture, the optical activities of these enantiomers cancel each other out, leading to zero optical rotation. (c) Allyl chloride is hydrolysed more readily than n-propyl chloride.
Allyl chloride is hydrolysed more readily than n-propyl chloride The allyl carbocation is stabilized by resonance with the adjacent double bond, making the reaction proceed more easily. In contrast, the n-propyl carbocation does not have this resonance stabilization, making it less stable and slower to undergo hydrolysis.