Name the product of the following benzene halogenation reaction.

• A. chlorobenzene
• B. 1,1-dichlorobenzene
• C. 1,2-dichlorobenzene
• D. 1,4-dichlorobenzene

Answer: (A)

Verified step by step guidance

1. Identify the starting material and the reagents involved in the reaction. Here, the starting material is chlorobenzene, and the reaction involves halogenation (addition of chlorine) in the presence of a catalyst such as FeCl3.
2. Understand the directing effects of substituents on the benzene ring. The chlorine substituent on chlorobenzene is an ortho/para-directing group due to its electron-donating resonance effect, despite being deactivating overall.
3. Predict the positions on the benzene ring where the new chlorine atom will be introduced. Because chlorine directs new substituents to the ortho and para positions relative to itself, the new chlorine will add to either the 2- (ortho) or 4- (para) position.
4. Determine the possible products. The reaction will produce dichlorobenzene isomers where the two chlorine atoms are either adjacent (1,2-dichlorobenzene) or opposite each other (1,4-dichlorobenzene).
5. Select the correct product name based on the substitution pattern. Since the reaction adds one chlorine to chlorobenzene, the product is either 1,2-dichlorobenzene or 1,4-dichlorobenzene, not chlorobenzene or 1,1-dichlorobenzene (which is not possible on a benzene ring).