How can the following conversions be carried out:

(i) Aniline to bromobenzene

(ii) Chlorobenzene to 2-chloroacetophenone

(iii) Chloroethane to butane

OR

What happens when

(i) chlorobenzene is treated with Cl₂/FeCl₃,

(ii) Ethyl chloride is treated with AgNO₂,

(iii) 2-bromopentane is treated with alcoholic KOH?

Write the chemical equations in support of your answer.

(i) When aniline is treated with sodium nitrite, a diazonium salt is formed. Mixing this solution of diazonium salt with CuBr₂ results in replacement of diazonium group by Br.

(ii)

Chlorobenzene is treated with acetyl chloride in the presence of anhydrous AlCl₃ to give a mixture 2-chloroacetophenone and 4- chloroacetophenone.

(iii)

Alkyl halides when treated with metallic Na in presence of dry ether gives a product in which 2 alkyl groups are joined together. Ths is called Wurtz reaction.

OR

(i) When chlorobenzene is treated with Cl₂/FeCl_3, halogenations reaction takes place and a mixture of dichlorobenzene is formed with para product being major product.

(ii) When ethyl chloride is treated with AgNO₂, nucleophilic substitution reaction takes place and NO₂ is substituted at the place of Cl giving nitroethane.

CH₃CH₂Cl + AgNO₂ ¾ CH₃CH₂NO₂ + AgCl

(iii) When 2-bromopentane is treated with alcoholic KOH, it undergoes elimination reaction which is governed by Saytzeff rule. The compound has more than one β-hydrogen, hence there is a possibility of more than one product. According to Saytzeff Rule, the preferred product is one which has the more number of alkyl groups attached to the doubly bonded carbon atom. Hence the major product is pent-2-ene and the minor product is pent-1-ene.

CH₃CH(Br)CH₂CH₂CH₃ + alc. KOH ^-HBr¾ CH₃CH₂CH₂CH=CH₂+CH₃CH₂CH=CHCH₃