Question

Predict the major product at the end of each sequence.(b)

Accepted Answer

Step 1: Analyze the first reaction in the sequence. The benzene ring undergoes electrophilic aromatic substitution with Cl₂ in the presence of AlCl₃, a Lewis acid catalyst. This reaction introduces a chlorine atom onto the benzene ring. The chlorine substituent is an electron-withdrawing group and directs subsequent substitutions to the meta position. Step 2: Consider the second reaction in the sequence. The benzene ring reacts with SO₃ in the presence of H₂SO₄, which is a sulfonation reaction. The sulfonic acid group (-SO₃H) is introduced onto the benzene ring. Since the chlorine substituent directs substitutions to the meta position, the sulfonic acid group will be added to the meta position relative to the chlorine atom. Step 3: Draw the intermediate product after the first reaction, showing the benzene ring with a chlorine atom attached. Then, draw the final product after the second reaction, showing the benzene ring with both the chlorine atom and the sulfonic acid group in a meta relationship. Step 4: Confirm the regioselectivity of the reactions by considering the electronic effects of the substituents. Chlorine is an electron-withdrawing group due to its inductive effect, and it directs electrophilic substitutions to the meta position. The sulfonation reaction follows this directive. Step 5: Ensure the major product is correctly predicted by verifying the positions of the substituents on the benzene ring. The final product should have the chlorine atom and the sulfonic acid group in a meta relationship, consistent with the directing effects of the chlorine substituent.

Predict the major product at the end of each sequence.
(b)

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Key Concepts

Electrophilic Aromatic Substitution

Reagents and Catalysts

Sulfonation of Aromatic Compounds