Question

Sucrose is not a reducing sugar since:

• A. it is chemically stable.
• B. it contains no free aldehyde or keto group adjacent to a ${}_{╱}^{╲}CHOH$ group.
• C. it is built up of a fructose unit.
• D. it is optically active.

Answer 1

The correct option is B it contains no free aldehyde or keto group adjacent to a ${}_{╱}^{╲}CHOH$ group.

Sucrose is not a reducing sugar since it contains no free aldehyde or keto group adjacent to a ${}_{╱}^{╲}CHOH$
group.

Sucrose is a non-reducing sugar because the two monosaccharide units are held together by a glycosidic linkage between C1 of α-glucose and C2 of β-fructose. Since the reducing groups of glucose and fructose are involved in glycosidic bond formation, sucrose is a non-reducing sugar.

Note: Reducing sugars reduce Fehling's solution and Tollen's reagent. All monosaccharides are reducing sugars. Disaccharides in which aldehydic and ketonic groups are free, behave as reducing sugars.