Question

Which of the following reaction will give 1 – methoxy – 4 – nitrobenzene.

1. 4 – nitro – 1 – bromobenzene + sodium methoxide.

2. 4 – nitrosodium phenoxide + bromomethane

Answer 1

Chemically both sets equally possible. In Set – 1, the Br – atom is activated by electron withdrawing effect of – NO group. Therefore nucleophilic attack by CH₃ONa followed by elimination of NaBr gives the desired ether. 

Step 1:

In set – 2, nucleophilic attack by 4 – nitrosodium phenoxide ion on methyl bromide gives the desired ether.

Since alkyl halides (CH₃Br) are more reactive than aryl halides in nucleophilic substitution reactions, therefore set – 2 reactants are preferred.