Which of the following does/do not react with Fehling's solution?

Options

A. Benzaldehyde
B. Acetaldehyde
C. Glucose
D. Acetophenone

Answer

To determine which of the given compounds do not react with Fehling's solution, we need to understand the conditions under which a compound will react with this solution. Fehling's solution is used to test for the presence of reducing sugars and aldehydes. The key points to consider are:

1. **Understanding Fehling's Solution**: Fehling's solution contains copper(II) ions (Cu²⁺) which are reduced to copper(I) oxide (Cu₂O) in the presence of reducing agents, such as aldehydes.

2. **Enolate Formation**: For certain aldehydes to react with Fehling's solution, they must be able to form an enolate ion. This requires the presence of alpha hydrogen atoms adjacent to the carbonyl group.

3. **Identifying Alpha Hydrogens**: Compounds that lack alpha hydrogens cannot form enolates and therefore will not react with Fehling's solution.

Now, let's analyze the given compounds:

### Step 1: Analyze Each Compound
- **Benzyldehyde (C₆H₅CHO)**:
- Structure: C₆H₅-CHO
- Alpha Hydrogens: No (the carbon adjacent to the carbonyl is part of a phenyl group, which has no hydrogen).

- **Acetaldehyde (CH₃CHO)**:
- Structure: CH₃-CHO
- Alpha Hydrogens: Yes (the methyl group has three hydrogens).

- **Glucose (C₆H₁₂O₆)**:
- Structure: C₆H₁₂O₆ (contains multiple hydroxyl groups and aldehyde).
- Alpha Hydrogens: Yes (the carbon adjacent to the aldehyde has hydrogens).

- **Acetophenone (C₆H₅C(O)CH₃)**:
- Structure: C₆H₅-C(=O)-CH₃
- Alpha Hydrogens: Yes (the methyl group has three hydrogens).

### Step 2: Conclusion
Based on the analysis, the only compound that does not react with Fehling's solution is **Benzyldehyde** because it lacks alpha hydrogens.

### Final Answer
**Benzyldehyde does not react with Fehling's solution.**

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