Although chlorine is an electron withdrawing group, yet it is ortho-, Para-directing in electrophilic aromatic substitution reactions. Explain why it is so?
Chlorine withdraws electrons through inductive effect and releases electrons through resonance. Through inductive effect, chlorine destabilises the intermediate carbocation formed during the Electrophilic substitution
Through resonance, halogen tends to stabilise the carbocation and the effect is more pronounced at ortho-and Para-position. The inductive effect is stronger than resonance and causes net electron withdrawal and thus causes net deactivation. The resonance effect tends to oppose the inductive effect for the attack at ortho-and Para-position and hence makes the deactivation less for ortho- and Para-attack. Reactivity is thus controlled, by the stronger inductive effect and orientation is controlled by a resonance effect.
Answer the following:
(i) Haloalkanes easily dissolve in organic solvents, why?
(ii) What is known as a racemic mixture? Give an example.
(iii) Of the two Bromo derivatives, C6H5CH(CH3)Br and C6H5CH(C6H5)Br, which one is more reactive in Sn1 substitution reaction and why?
Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same?
