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Biomolecules appeared 36 times across 3 years — 4.2% of Chemistry. This question is from Carbohydrate Structures.

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Which of the following is the correct structure of L-fructose?

Solution & Explanation

Related Formula

D- and L-enantiomers are non-superimposable mirror images of each other at all chiral centers.

Core Logic

D-fructose has the -OH group at C-5 positioned on the right in its Fischer projection. L-fructose is the exact enantiomer (mirror image) of D-fructose, meaning all chiral centers (C-3, C-4, C-5) have inverted configurations, with the -OH group at C-5 on the left.

Step 1: Structural Verification

Structure (3) correctly displays the Fischer projection of L-fructose with C-3 -OH on the right, and C-4, C-5 -OH groups on the left.

Pattern Recognition

L-isomer is the exact mirror image of the D-isomer across all stereocenters.

Chapter Mix

Class 12 Chemistry: Biomolecules

Reference Study Guides

Biomolecules

More Biomolecules Previous-Year Questions — Page 8

Q78 jee_main_2024_31_jan_morning Reactions of Glucose
Match List I with List II
LIST-ILIST-II
A. Glucose/NaHCO₃/ΔI. Gluconic acid
B. Glucose/HNO₃II. No reaction
C. Glucose/HI/ΔIII. n-hexane
D. Glucose/Bromine waterIV. Saccharic acid
Choose the correct answer from the options given below:
  • A. A-IV, B-I, C-III, D-II
  • B. A-II, B-IV, C-III, D-I
  • C. A-III, B-II, C-I, D-IV
  • D. A-I, B-IV, C-III, D-II

Solution

Core Logic

Matching the reactions of glucose: (A) Glucose does not react with NaHCO₃, so there is no reaction. (A arrow II) (B) Oxidation of glucose with strong oxidizing agents like HNO₃ yields a dicarboxylic acid called saccharic acid. (B arrow IV) (C) Prolonged heating of glucose with HI forms n-hexane, indicating a straight chain of six carbon atoms. (C arrow III) (D) Oxidation with mild agents like bromine water converts glucose to gluconic acid. (D arrow I)

Chapter Mix

Class 12 Chemistry: Biomolecules

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)