Which of the following gives an alcohol and salt of carboxylic acid when reacted with conc. NaOH .

Options

A. `CH_(3) CHO`
B. `C_(6) H_(5) CHO`
C. `CH_(3) COCH_(3)`
D. `C_(6) H_(5)COCH_(3)`

Answer

To solve the question of which compound gives an alcohol and a salt of a carboxylic acid when reacted with concentrated NaOH, we need to understand the Cannizzaro reaction. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Cannizzaro Reaction
The Cannizzaro reaction occurs with aldehydes that do not have alpha hydrogens. In this reaction, one molecule of the aldehyde is oxidized to form a carboxylic acid salt, while another molecule is reduced to form an alcohol.

**Hint:** Look for aldehydes without alpha hydrogens to identify candidates for the Cannizzaro reaction.

### Step 2: Identify Alpha Hydrogens
Alpha hydrogens are the hydrogens attached to the carbon adjacent to the carbonyl carbon (C=O). If an aldehyde has no alpha hydrogens, it can undergo the Cannizzaro reaction.

**Hint:** Check the structure of each aldehyde to see if there are any hydrogens on the alpha carbon.

### Step 3: Analyze Each Compound
1. **CH3CHO (Acetaldehyde)**:
- This compound has three alpha hydrogens (from the methyl group).
- Therefore, it cannot undergo the Cannizzaro reaction.

2. **C6H5CHO (Benzaldehyde)**:
- This compound has no alpha hydrogens because the carbonyl carbon is directly attached to the benzene ring.
- It can undergo the Cannizzaro reaction, producing benzyl alcohol (C6H5CH2OH) and sodium benzoate (C6H5COO-Na+).

3. **CH3CH=O (Propanal)**:
- This compound has three alpha hydrogens (from the ethyl group).
- Therefore, it cannot undergo the Cannizzaro reaction.

4. **C6H5COCH3 (Acetophenone)**:
- This compound has three alpha hydrogens (from the methyl group adjacent to the carbonyl).
- Therefore, it cannot undergo the Cannizzaro reaction.

**Hint:** Eliminate compounds that have alpha hydrogens from consideration.

### Step 4: Conclusion
From the analysis, only **C6H5CHO (Benzaldehyde)** meets the criteria for the Cannizzaro reaction, producing both an alcohol and a salt of a carboxylic acid.

**Final Answer:** The compound that gives an alcohol and a salt of a carboxylic acid when reacted with concentrated NaOH is **C6H5CHO (Benzaldehyde)**.