See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Enol Content Analysis **Understanding Enol Form:** The enol tautomer (C=C-OH) forms through keto-enol tautomerism. The stability and abundance of the enol form depends on: 1. **Conjugation** of the C=C double bond with electron-withdrawing or aromatic groups 2. **Resonance stabilization** of the enolate intermediate 3. **Inductive effects** from adjacent groups --- **Evaluating Each Option:** **(A) Phenylpyruvic acid derivative:** - Two carbonyl groups compete for enolization; the electron-withdrawing effects destabilize enol formation - Conjugation exists but is limited by competing carbonyls **(B) Phenylacetaldehyde derivative with ketone:** - Aldehyde group ($-CHO$) is **highly electron-withdrawing** - The ketone carbonyl conjugates with the benzene ring, stabilizing its enolate - The aldehyde's strong electron-withdrawal **activates enolization of the adjacent ketone** by making the enolic OH more stable through resonance - Single carbonyl makes it easier to form enol **(C) Benzil-like compound:** - Two conjugated carbonyls create extended conjugation but competing enolization sites - Neither carbonyl dominates; enol content divided **(D) Amide derivative:** - Amide nitrogen has lone pair; competes with C=O in resonance - Reduces carbonyl reactivity and enol formation --- **Answer: (B)** The aldehyde's electron-withdrawing effect maximizes enol stabilization of the ketone, while the single ketone carbonyl (without competition) undergoes preferential enolization, yielding the highest % enol content in the liquid.