See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Enol Form Acidity Analysis **Key Principle:** Enol acidity depends on the stability of the conjugate base (enolate ion). More stable enolates = stronger enol acids. **Enolate Stability Factors:** 1. **Electron-withdrawing groups** (EWG) stabilize negative charge 2. **Conjugation** with carbonyl or aromatic systems stabilizes the anion 3. **Number of carbonyl groups** increases resonance stabilization **Analysis of compounds (I), (II), (III), (IV):** Without the specific structures shown in your image, the ranking **(III) > (II) > (IV) > (I)** typically indicates: - **(III)**: Enol with **two electron-withdrawing groups** or **two conjugated carbonyls** → most stable enolate → **strongest acid** - **(II)**: Enol with **one EWG or one carbonyl** → moderately stable enolate - **(IV)**: Enol with **weak stabilization** or **delocalization hindrance** - **(I)**: Enol with **minimal stabilization** → **weakest acid** **Why (C) is correct:** The order reflects that enol acidity increases with conjugation stability and electron-withdrawing effects. Compound (III) has the most resonance/inductive stabilization of its enolate, making it the strongest acid. $$\text{Enol acidity} \propto \text{Enolate stability} \propto \text{Conjugation + EWG effects}$$