Final answer:
The correct synthesis of p-tert-butylnitrobenzene from benzene involves first a Friedel-Crafts alkylation with tert-butyl chloride and AlCl3, followed by nitration with HNO3 and H2SO4. This sequence introduces the tert-butyl group first, making the introduction of the nitro group at the para position possible. Option A is the correct answer.
Step-by-step explanation:
To synthesize p-tert-butylnitrobenzene from benzene, we need to carry out a two-step synthesis using electrophilic aromatic substitution reactions. The desired product has two substituents on the benzene ring: a tert-butyl group and a nitro group. These substituents direct incoming groups to certain positions on the benzene ring, which is crucial for obtaining the para product.
Firstly, we should introduce the tert-butyl group onto the benzene ring. This is because the nitro group is a strong deactivating and meta-directing group, which would make it difficult to introduce a bulky tert-butyl group at the para position afterward. Thus, the correct sequence would be to first alkylate the benzene ring with tert-butyl chloride ((CH3)3CCl) using an AlCl3 catalyst to get tert-butylbenzene. This step is known as the Friedel-Crafts alkylation.
Following this, the second step is the nitration of the alkylated benzene. This involves treating the tert-butylbenzene with a nitrating mixture of nitric acid (HNO3) and sulfuric acid (H2SO4), which introduces the nitro group at the para position relative to the tert-butyl group, due to the strong electron-donating effect of the tert-butyl group.
Hence, the correct sequence of reactions is Option A: (CH3)3CCl / AlCl3 then HNO3 / H2SO4.