From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :

Year	2026	2025	2024	Total
Questions	9	19	8	36

Year

2026

2025

2024

Total

Questions

Solution & Explanation

Core Logic

Tollens' reagent oxidizes aldehydes. In cyclic sugars, this requires a free hemiacetal group (an anomeric carbon bonded to an $-OH$ $-OH$ group) to allow mutarotation and open-chain aldehyde formation.

Step 1: Structural Analysis

Structures (A) and (D) possess a free $-OH$ $-OH$ group at the anomeric carbon (hemiacetal linkage). They are reducing sugars and will react with Tollens' reagent. Structures (B) and (C) have an $-OCH₃$ $-OCH_3$ group at the anomeric carbon instead of a free $-OH$ $-OH$. These are full acetals (glycosides) and cannot ring-open. Thus, they are non-reducing sugars.

Pattern Recognition

Hemiacetal ( $-OH$ $-OH$ on anomeric C) = Reducing Sugar. Acetal ( $-OR$ $-OR$ on anomeric C) = Non-Reducing Sugar.

Chapter Mix

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Q78 jee_main_2024_31_jan_morning Reactions of Glucose

Match List I with List II

LIST-I	LIST-II
A. Glucose/ $NaHCO₃$ $NaHCO_3$/ $Δ$ $\Delta$	I. Gluconic acid
B. Glucose/ $HNO₃$ $HNO_3$	II. No reaction
C. Glucose/HI/ $Δ$ $\Delta$	III. n-hexane
D. Glucose/Bromine water	IV. Saccharic acid

Choose the correct answer from the options given below:

A. $A-IV, B-I, C-III, D-II$ $\text{A-IV, B-I, C-III, D-II}$
B. $A-II, B-IV, C-III, D-I$ $\text{A-II, B-IV, C-III, D-I}$
C. $A-III, B-II, C-I, D-IV$ $\text{A-III, B-II, C-I, D-IV}$
D. $A-I, B-IV, C-III, D-II$ $\text{A-I, B-IV, C-III, D-II}$

Solution

Core Logic

Matching the reactions of glucose: (A) Glucose does not react with $NaHCO₃$ $NaHCO_3$, so there is no reaction. (A $arrow$ $\rightarrow$ II) (B) Oxidation of glucose with strong oxidizing agents like $HNO₃$ $HNO_3$ yields a dicarboxylic acid called saccharic acid. (B $arrow$ $\rightarrow$ IV) (C) Prolonged heating of glucose with $HI$ $HI$ forms n-hexane, indicating a straight chain of six carbon atoms. (C $arrow$ $\rightarrow$ III) (D) Oxidation with mild agents like bromine water converts glucose to gluconic acid. (D $arrow$ $\rightarrow$ I)

Chapter Mix

Class 12 Chemistry: Biomolecules

From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :
Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars

Solution & Explanation

Core Logic

Step 1: Structural Analysis

Pattern Recognition

Chapter Mix

Reference Study Guides

More Biomolecules Previous-Year Questions — Page 8

Solution

Core Logic

Chapter Mix

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From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are : Reducing and Non-Reducing Sugars Reducing and Non-Reducing Sugars Reducing and Non-Reducing Sugars Reducing and Non-Reducing Sugars

Solution & Explanation

Core Logic

Step 1: Structural Analysis

Pattern Recognition

Chapter Mix

Reference Study Guides

More Biomolecules Previous-Year Questions — Page 8

Solution

Core Logic

Chapter Mix

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From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are :
Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars

Reducing and Non-Reducing Sugars