Which of the following does not reduce Benedict's solution?

Options

A. Glucose
B. Fructose
C. Sucrose
D. Aldehyde

Explanation

To determine which of the following substances does not reduce Benedict's solution, we need to analyze each option in relation to their chemical structures and properties. Benedict's solution is a chemical reagent that is used to test for the presence of reducing sugars, which can reduce copper(II) ions (Cu²⁺) to copper(I) oxide (Cu₂O), resulting in a color change.

### Step-by-Step Solution:

1. **Understanding Benedict's Solution**:
- Benedict's solution contains copper(II) sulfate and is used to test for reducing sugars. When a reducing sugar is present, it reduces the Cu²⁺ ions to Cu₂O, which precipitates out as a red solid.

2. **Analyzing the Options**:
- **Option 1: Glucose**
- Glucose is an aldose sugar with a free aldehyde group. It can reduce Benedict's solution and will yield a positive result.

- **Option 2: Fructose**
- Fructose is a ketose sugar. Although it does not have a free aldehyde group, it can undergo tautomerization to form an aldehyde under basic conditions. Therefore, fructose can also reduce Benedict's solution and will yield a positive result.

- **Option 3: Sucrose**
- Sucrose is a disaccharide formed from glucose and fructose linked by a glycosidic bond. This linkage prevents sucrose from having a free aldehyde group, meaning it cannot reduce Benedict's solution. Thus, it will yield a negative result.

- **Option 4: Aldehyde**
- Aldehydes are known to reduce Benedict's solution. They have a free carbonyl group (CHO) that can easily participate in the reduction reaction.

3. **Conclusion**:
- After analyzing all options, we find that **sucrose** is the only substance that does not reduce Benedict's solution. Therefore, the correct answer is **Option 3: Sucrose**.