QNEET-2024-Ch-3: NEET 2024 Chemistry - Class 12 NEET-2024-Ch-3 Solution: Major products A and B formed in the following reaction…

**Core Concept & Governing Principle** The reaction sequence involves (i) oxidation of a primary alcohol to an aldehyde, (ii) nucleophilic addition of phenol to the aldehyde forming a benzylic ether, and (iii) further oxidation of the benzylic carbon to a carboxylic acid which then undergoes intramolecular esterification (lactonisation). The major products are determined by the most favourable oxidation state changes and the stability of the intermediates. **Step 1: Identify the functional groups in the starting material** The substrate contains a primary –CH₂OH group attached to an aromatic ring bearing a phenolic –OH group. **Step 2: First oxidation (e.g., PCC, Swern, or Na₂Cr₂O₇/H₂SO₄)** Primary alcohol → aldehyde. The phenolic –OH remains unchanged under these conditions. **Step 3: Nucleophilic addition of the phenolic oxygen to the aldehyde** The phenolic oxygen attacks the electrophilic carbonyl carbon of the newly formed aldehyde, giving a hemi‑acetal (benzylic alkoxy‑alcohol). Because the aromatic ring can delocalise the positive charge, this intermediate is relatively stable. **Step 4: Further oxidation of the benzylic carbon** A stronger oxidising agent (e.g., KMnO₄, Na₂Cr₂O₇/H₂SO₄) oxidises the benzylic carbon bearing the –O–Ar substituent from the alcohol oxidation level to a carboxylic acid. **Step 5: Intramolecular esterification (lactone formation)** The carboxylic acid and the adjacent phenolic oxygen are positioned ortho‑to‑each other on the same aromatic ring, allowing a favorable 5‑ or 6‑membered cyclic ester (lactone) to form with loss of water. **Step 6: Identify the major products** - **Product A**: The lactone obtained after cyclisation (major, thermodynamically favoured). - **Product B**: The benzylic ether (hemi‑acetal) formed after the phenolic addition, which can be isolated if the oxidation is stopped prematurely. These two structures correspond exactly to the structures shown in option **A**. **Final Conclusion & Correct Option** The major products of the described reaction sequence are the cyclic ester (lactone) and the benzylic ether shown in option **A**.