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JEE Main · 2023 · 13 Apr 2023 · Shift 1 · Biomolecules

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D- (+)- Glyceraldehyde
(iii)

The products formed in the above reaction are
  1. (A)Two optically active products
  2. (B)One optically active and one meso product✓ Correct
  3. (C)One optically inactive and one meso product.
  4. (D)Two optically inactive products

Answer: (B)

Solution

D-(+)-Glyceraldehyde has one chiral center. When it reacts with HCN, the cyanide attacks the carbonyl from both faces, creating a new chiral center. This gives two diastereomeric cyanohydrins. Upon hydrolysis with H₂O/H⁺ followed by oxidation with HNO₃, these form two α-hydroxy acids. One product retains optical activity (has non-superimposable mirror image), while the other is a meso compound (has an internal plane of symmetry and is optically inactive despite having chiral centers).

JEE Main · 2023 · 13 Apr 2023 · Shift 1 · Single correct option

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