Step 1: Understanding the Question:
This is a Friedel-Crafts alkylation reaction. We need to identify the starting aromatic compound 'A'.
Step 3: Detailed Explanation:
The products are 2-chlorotoluene and 4-chlorotoluene.
- 2-chlorotoluene is ortho-chlorotoluene.
- 4-chlorotoluene is para-chlorotoluene.
In these products, a methyl group (\( \text{-CH}_3 \)) from chloromethane has been added to a benzene ring that already contains a chlorine atom.
Therefore, the starting material 'A' must be Chlorobenzene.
The chlorine atom on the benzene ring is an ortho/para directing group, which explains why the methyl group attaches to positions 2 and 4.
Step 4: Final Answer:
The compound 'A' is Chlorobenzene.