See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: π-Donor and π-Acceptor Character in Biphenyl **Step 1: Understand π-donors and π-acceptors** - **π-donors**: Aromatic rings with electron-donating groups that increase electron density in the π-system - **π-acceptors**: Aromatic rings with electron-withdrawing groups that decrease electron density in the π-system **Step 2: Analyze biphenyl structure** Biphenyl is two unsubstituted benzene rings connected by a single C–C bond. Each benzene ring is identical with no substituents. **Step 3: Consider resonance effects** When the two rings are conjugated through the central C–C bond, resonance structures form where: - One ring acts as a **π-donor**, pushing electron density into the conjugated system - The other ring acts as a **π-acceptor**, withdrawing electron density from the conjugated system This creates a donor-acceptor resonance interaction that stabilizes the system. **Step 4: Evaluate options** - (A) False: Rings aren't both donors - (B) False: Rings aren't both acceptors - **(C) True**: Resonance polarization creates complementary donor-acceptor character between the two rings - (D) False: Significant resonance exists due to conjugation **Answer: (C)** — One ring functions as a π-donor and the other as a π-acceptor through resonance stabilization of the conjugated system.