JEE Main · 2022 · Shift-IImediumBIO-030

When sugar 'X' is boiled with dilute H2SO4 in alcoholic solution, two isomers 'A' and 'B' are formed. 'A' on oxidation…

Biomolecules · Class 12 · JEE Main Previous Year Question

Question

When sugar 'X' is boiled with dilute \ceH2SO4\ce{H2SO4} in alcoholic solution, two isomers 'A' and 'B' are formed. 'A' on oxidation with \ceHNO3\ce{HNO3} yields saccharic acid whereas 'B' is laevorotatory. The compound 'X' is:

Options
  1. a

    Maltose

  2. b

    Sucrose

  3. c

    Lactose

  4. d

    starch

Correct Answerb

Sucrose

Detailed Solution

Step 1: Sucrose Hydrolysis — Boiling sucrose ('X') with dilute acid yields an equimolar mixture of D-(+)\text{D-(+)}-glucose and D-(-)\text{D-(-)}-fructose.

Step 2: Identifying Products — Glucose ('A') is an aldose that oxidizes to saccharic acid. Fructose ('B') is a ketose and is strongly laevorotatory ([α]D=92.4[\alpha]_D = -92.4^\circ).

Step 3: Conclusion — The description of 'X' yielding these two specific isomers identifies the starting compound as sucrose.

Remember: This reaction is the basis for the production of 'invert sugar'.

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When sugar 'X' is boiled with dilute H2SO4 in alcoholic solution, two isomers 'A' and 'B' are… (JEE Main 2022) | Canvas Classes