Cannizzaro reaction is not given by

Options

A. trimethylacetaldehyde
B. acetaldehyde
C. benzaldehyde
D. formaldehyde

Answer

To determine which compound does not undergo the Cannizzaro reaction, we need to understand the conditions required for this reaction to occur. The Cannizzaro reaction is a redox disproportionation reaction that typically involves aldehydes that lack alpha-hydrogens.

Here’s a step-by-step solution:

### Step 1: Understand the Cannizzaro Reaction
The Cannizzaro reaction involves the disproportionation of aldehydes in the presence of a strong base. In this reaction, one molecule of aldehyde is oxidized to a carboxylic acid, while another molecule is reduced to an alcohol.

**Hint:** Remember that disproportionation means one species is both oxidized and reduced.

### Step 2: Identify Alpha-Hydrogens
For an aldehyde to participate in the Cannizzaro reaction, it must not have any alpha-hydrogens. Alpha-hydrogens are the hydrogen atoms attached to the carbon adjacent to the carbonyl group.

**Hint:** Look at the structure of the aldehyde and count the hydrogen atoms on the carbon next to the carbonyl carbon.

### Step 3: Analyze Given Compounds
Now, let’s analyze the given compounds:
1. **Benzaldehyde (C6H5CHO)** - This compound has no alpha-hydrogens (the carbon adjacent to the carbonyl is part of the benzene ring).
2. **Formaldehyde (HCHO)** - This compound also has no alpha-hydrogens (it has only one carbon).
3. **Acetaldehyde (CH3CHO)** - This compound has three alpha-hydrogens (from the methyl group).
4. **Trimethylacetaldehyde** - This compound has no alpha-hydrogens (the structure prevents the presence of alpha-hydrogens).

**Hint:** Check the structure of each compound to determine the presence of alpha-hydrogens.

### Step 4: Conclusion
From the analysis, we can conclude that:
- Benzaldehyde and formaldehyde can undergo the Cannizzaro reaction.
- Trimethylacetaldehyde can also undergo the Cannizzaro reaction.
- Acetaldehyde, however, has alpha-hydrogens and therefore does not undergo the Cannizzaro reaction.

Thus, the compound that does not show the Cannizzaro reaction is **Acetaldehyde**.

**Final Answer:** Acetaldehyde does not undergo the Cannizzaro reaction.