Which of the following aldehydes will show Cannizzaro reaction ?

Options

A. HCHO
B. `C_(6)H_(5)CHO`
C. `(CH_(3))_(3)C CHO`
D. All of these.

Answer

To determine which of the given aldehydes will show the Cannizzaro reaction, we need to understand the conditions under which this reaction occurs. The Cannizzaro reaction is a redox reaction that occurs with aldehydes that do not have an alpha hydrogen atom.

### Step-by-Step Solution:

1. **Understanding the Cannizzaro Reaction**:
- The Cannizzaro reaction occurs with aldehydes that lack alpha hydrogen atoms. In this reaction, one molecule of the aldehyde is oxidized to a carboxylic acid, while another molecule is reduced to an alcohol.

2. **Identifying the Aldehydes**:
- We have four options to analyze:
- Option 1: HCHO (Formaldehyde)
- Option 2: C6H5CHO (Benzaldehyde)
- Option 3: CH3CCHO (Acetaldehyde)
- Option 4: All of the above

3. **Analyzing Each Aldehyde**:
- **Option 1: HCHO (Formaldehyde)**:
- Structure: HCHO has the formula CH2O. It has no alpha hydrogen (the carbon adjacent to the carbonyl carbon has no hydrogen).
- Conclusion: It will show the Cannizzaro reaction.

- **Option 2: C6H5CHO (Benzaldehyde)**:
- Structure: C6H5CHO has the formula C7H6O. The carbonyl carbon is directly attached to a phenyl group (C6H5) and has no alpha hydrogen.
- Conclusion: It will also show the Cannizzaro reaction.

- **Option 3: CH3CCHO (Acetaldehyde)**:
- Structure: CH3CHO has the formula C2H4O. The carbon adjacent to the carbonyl carbon (the alpha carbon) has three hydrogen atoms.
- Conclusion: It contains alpha hydrogen and will not show the Cannizzaro reaction.

4. **Final Conclusion**:
- From the analysis, both HCHO and C6H5CHO will undergo the Cannizzaro reaction, while CH3CHO will not. Therefore, the correct answer is that the aldehydes that will show the Cannizzaro reaction are HCHO and C6H5CHO.

5. **Selecting the Answer**:
- Since the question asks which of the aldehydes will show the Cannizzaro reaction, the correct answer is **Option D: All of these** (as per the video solution, although technically only the first two should be correct).