See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

## Solution: Steric Inhibition of Resonance **Steric inhibition of resonance** occurs when bulky substituents prevent a group from achieving coplanarity with the aromatic ring, blocking resonance stabilization. **Analysis of each option:** **(A) Aminophenol** — $NH_2$ and $OH$ are both small groups. They can easily achieve coplanarity with the benzene ring and participate in resonance electron donation. **Resonance is NOT inhibited.** **(B) N,N-dimethylaniline with ortho-methyl** - The dimethylamino group has three methyl groups around nitrogen - The ortho-methyl creates steric clash - This forces the $N(CH_3)_2$ group out of planarity - Resonance electron donation is inhibited ✓ **(C) N,N-dimethyl-2,6-dimethylaniline** - Multiple bulky methyl groups (2,6-positions and on N) - Severe steric hindrance prevents planarity - Strong steric inhibition of resonance ✓ **(D) 2,6-dimethylnitrobenzene** - The $NO_2$ group is small enough to remain planar despite ortho-methyls - Resonance is possible (though restricted) - Steric inhibition is minimal **Answer: (A)** — Both $NH_2$ and $OH$ are small, unhindered groups that freely resonate with the benzene ring. No steric inhibition occurs because there are no bulky substituents to create steric clashes preventing coplanarity.