Question

In the following compound, least number of mono chlorination is possible:

• A. $ C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{3}} $
• B.
• C.
• D.

Answer 1

Answer: (D)

Write chlorination reaction for all of them to find which gives of the maximum number of monochlorination product.
(a) $CH _{3} CH _{2} CH _{2} CH _{2} CH _{3}+ Cl _{2} \xrightarrow{{ UV }}$
$ClCH _{2}-\left( CH _{2}\right)_{3} CH _{3}+ CH _{3}- \overset{\underset{|}{C}l}{CH} -\left( CH _{2}\right)_{2} CH _{3}+ CH _{3}- CH _{2}- \underset{\overset{|}{C}l}{CH} - CH _{2}- CH _{3}$
$\therefore $ Total $3$ monochlorinated products are formed.
(b) $CH _{3}- \underset{\overset{|}{C}H_3}{CH} - CH _{2}- CH _{3}+ Cl _{2} \xrightarrow{{ UV }}$
$ClCH _{2}- \underset{\overset{|}{C}H_3}{CH} - CH _{2}- CH _{3}$
$+ CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}l}{C}} - CH _{2}- CH _{3}$
$+ CH _{3}- \underset{\overset{|}{C}H_3}{C}H - CH _{2}- CH _{2} Cl$
(c) $CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}H_3}{C}} - H + Cl _{2} \xrightarrow{{ Uv }}$
$CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}H_3}{C}} - Cl + CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}H_2Cl}{C}} - H$
$\therefore $ Total $2$- monochlorinated products are formed
(d) $CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}l}{C}} - CH _{3}+ Cl _{2} \xrightarrow{ Uv }$
$CH _{3}- \underset{\overset{|}{C}H_3}{\overset{\underset{|}{C}l}{C}} - CH _{2} Cl$
$\therefore $ Only one monochlorinated product formed.