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JEE Main · 2023 · 31 Jan 2023 · Shift 2 · Biomolecules

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Compound A, , given a tetraacetate with and oxidation of A with gives an acid, . Reduction of A with HI gives isopentane. The possible structure of A is :
  1. (A)(see structure)
    ✓ Correct
  2. (B)(see structure)
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (A)

Solution

Formation of a tetra-acetate shows that compound A carries four hydroxyl groups, and oxidation by bromine water to , a gain of one oxygen, shows a terminal aldehyde being raised to a carboxylic acid, so A is an aldopentose. Reduction with hydriodic acid stripping away every oxygen leaves isopentane, which fixes a branched, 2-methylbutane carbon framework rather than a straight chain. The structure meeting all three requirements is the branched-chain aldopentose whose five carbons form the isopentane skeleton with the aldehyde at one end and hydroxyl groups on the remaining carbons.

JEE Main · 2023 · 31 Jan 2023 · Shift 2 · Single correct option

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