Final answer:
The synthesis of p-chloronitrobenzene from benzene involves a nitration step followed by protection of the ortho and meta positions and a subsequent chlorination step to introduce the chlorine atom in the para position relative to the established nitro group.
Step-by-step explanation:
To synthesize p-chloronitrobenzene from benzene, a multi-step process that includes nitration and chlorination reactions must be followed. Firstly, benzene is nitrated using a mixture of concentrated sulfuric acid (H₂SO₄) and nitric acid (HNO₃) to introduce a nitro group (-NO₂), producing nitrobenzene. The specific reaction is:
NO₂
HNO₃ + H₂SO₄ → Nitrobenzene
Following nitration, the nitro group directs further electrophilic substitution to the meta position; therefore, we must protect the ortho and meta positions to achieve para substitution. After protecting these positions, the chlorination can take place, typically using chlorine (Cl₂) in the presence of a catalyst such as aluminum chloride (AlCl₃), to install the chlorine atom in the para position relative to the nitro group, yielding p-chloronitrobenzene. This is an example of electrophilic aromatic substitution.