Oligosaccharides: Sucrose
Structure of sucrose (non-reducing sugar), its formation from glucose and fructose, and hydrolysis products.
What is Oligosaccharides: Sucrose?
A carbohydrate formed by the linking of a small number (typically 2 to 10) of monosaccharide units.
Key formula / rule: Sucrose Hydrolysis
Key points
- Identify sucrose as a disaccharide.
- Describe the structure and linkage in sucrose.
- Explain why sucrose is a non-reducing sugar.
- List the products of sucrose hydrolysis.
Common exam trap
Confusing sucrose with reducing sugars.
Definitions
- Term
Oligosaccharide
- Meaning
A carbohydrate formed by the linking of a small number (typically 2 to 10) of monosaccharide units.
- Term
Disaccharide
- Meaning
An oligosaccharide composed of exactly two monosaccharide units joined by a glycosidic bond.
- Term
Glycosidic bond
- Meaning
A type of covalent bond that links a carbohydrate molecule to another group, which may be another carbohydrate or, in the case of glycosides, another functional group.
- Term
Reducing sugar
- Meaning
A sugar that has a free aldehyde or ketone group, or a hemiacetal or hemiketal group, which can reduce oxidizing agents.
- Term
Non-reducing sugar
- Meaning
A sugar that lacks a free aldehyde or ketone group (or hemiacetal/hemiketal) and therefore cannot reduce oxidizing agents under mild conditions.
- Term
Invert sugar
- Meaning
An equimolar mixture of D-glucose and D-fructose obtained from the hydrolysis of sucrose.
Learning objectives
Identify sucrose as a disaccharide.
Describe the structure and linkage in sucrose.
Explain why sucrose is a non-reducing sugar.
List the products of sucrose hydrolysis.
Formulae
- Name
Sucrose Hydrolysis
- Note
This reaction is catalyzed by acid or the enzyme invertase.
- Expression
C₁₂H₂₂O₁₁ (sucrose) + H₂O → C₆H₁₂O₆ (glucose) + C₆H₁₂O₆ (fructose)
Prerequisites
Monosaccharides (glucose, fructose)
Glycosidic bond formation
Reducing vs. Non-reducing sugars
Chirality and anomers
Common mistakes
Confusing sucrose with reducing sugars.
Incorrectly identifying the monosaccharide units or the type of glycosidic linkage.
Forgetting that both anomeric carbons are involved in the bond.
Keywords
Sucrose
Oligosaccharide
Disaccharide
Glucose
Fructose
Glycosidic bond
Non-reducing sugar
Hydrolysis
Invert sugar
Carbohydrate
Practice preview
The hydrolysis of sucrose yields:…
easy
When sucrose is hydrolyzed under acidic conditions, the specific rotation of the resulting solution changes from positive to negative. This phenomenon is known as:…
medium
The chemical formula of sucrose is C₁₂H₂₂O₁₁. Upon complete hydrolysis, it yields glucose and fructose, both of which have the chemical formula C₆H₁₂O₆. Which of the following equations correctly represents the hydrolysi…
medium