JEE Main · 2024 · 30 Jan 2024 · Shift 1 · Aldehydes Ketones and Carboxylic Acids

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Sugar which does not give reddish brown precipitate with Fehling's reagent is:
  1. (A)Sucrose✓ Correct
  2. (B)Lactose
  3. (C)Glucose
  4. (D)Maltose

Answer: (A)

Solution

Sucrose has no free anomeric (hemiacetal) carbon — both its anomeric carbons are tied up in the glycosidic bond — so it cannot reduce Fehling's reagent. Glucose, lactose and maltose each retain a free hemiacetal/aldehyde group and give a positive test.

JEE Main · 2024 · 30 Jan 2024 · Shift 1 · Single correct option

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