See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Determining % Enol Content Order **Step 1: Identify the structures** - (I) Ethyl acetate: $CH_3COOC_2H_5$ (ester, no enolizable H) - (II) Acetaldehyde: $CH_3CHO$ (aldehyde, one α-H) - (III) Acetylacetone: $CH_3COCH_2COCH_3$ (β-diketone, two α-H's) - (IV) Acrolein: $CH_2=CHCHO$ (α,β-unsaturated aldehyde) **Step 2: Apply enolization factors** The enol content depends on: - **Number of α-hydrogens**: More α-H's → higher enol % - **Resonance stabilization**: Conjugation and multiple carbonyl groups increase enol stability - **Structural factors**: β-Dicarbonyl compounds show dramatically enhanced enolization **Step 3: Rank by % enol content** $$\text{(III)} > \text{(IV)} > \text{(II)} > \text{(I)}$$ | Compound | % Enol | Reason | |----------|--------|--------| | **(III)** | ~76% | β-Diketone: two C=O groups with resonance-stabilized enol | | **(IV)** | ~6-10% | Conjugation with C=C increases enol stability vs simple aldehyde | | **(II)** | ~0.02% | Simple aldehyde; minimal enolization | | **(I)** | ~0% | Ester with no α-hydrogens; cannot enolize | **Answer: (A) $3 < 4 < 2 < 1$** ✓ This ordering reflects decreasing % enol content from compound 3 (III) down to compound 1 (I).