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JEE Main · 2023 · 30 Jan 2023 · Shift 1 · Practical and Analytical Chemistry

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Which of the following compounds would give the following set of qualitative analysis?
(i) Fehling's Test : Positive
(ii) Na fusion extract upon treatment with sodium nitroprusside gives a blood red colour but not
  1. (A)(see structure)
  2. (B)(see structure)
  3. (C)(see structure)
  4. (D)(see structure)
    ✓ Correct

Answer: (D)

Solution

A positive Fehling's test needs an easily oxidised aliphatic aldehyde; an aldehyde joined straight to an aromatic ring does not respond. A blood-red colour in the sodium fusion test signals that nitrogen and sulphur are both present together in the molecule. The structure carrying a thiazole ring, which supplies both nitrogen and sulphur, attached to a chain meets both demands: the side-chain aldehyde is aliphatic and reduces Fehling's reagent, while the ring atoms account for the nitrogen and sulphur. The compound answering both tests is the thiazole bearing the aliphatic side chain.

JEE Main · 2023 · 30 Jan 2023 · Shift 1 · Single correct option

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