NEET 2025, Chemistry Q38: Carboxylic Acid Derivatives

NEET2025Chemistry

Identify the suitable reagent for the following conversion:

A
(i) LiAlH $_{4}$ , (ii) H $^{+}$ /H $_{2}$ O
B
(i) AlH(iBu) $_{2}$ , (ii) H $_{2}$ O
C
(i) NaBH $_{4}$ , (ii) H $^{+}$ /H $_{2}$ O
D
H $_{2}$ / Pd-BaSO $_{4}$

Solution

DIBAL-H (diisobutylaluminium hydride, AlH(iBu) $_{2}$ ) selectively reduces an ester to an aldehyde at low temperature by adding just one hydride and stopping at the tetrahedral intermediate. Workup with water then releases the aldehyde.

LiAlH $_{4}$ and NaBH $_{4}$ would reduce the ester all the way to the primary alcohol (PhCH $_{2}$ OH), not the aldehyde.

H $_{2}$ /Pd-BaSO $_{4}$ (Rosenmund) reduces acid chlorides, not esters, to aldehydes.

$∴$ The correct reagent is DIBAL-H followed by aqueous workup.

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NEET 2025, Chemistry Q38: Carboxylic Acid Derivatives

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