Cynohydrin of the following compound on hydrolysis gives optically active product :

Options

A. HCHO
B. `CH_3CHO`
C. `CH_3COCH_3`
D. All of the above

Answer

To solve the problem of determining which cyanohydrin gives an optically active product upon hydrolysis, we will analyze each compound step by step.

### Step 1: Identify the compounds
We have three compounds to analyze:
1. Compound A: HC≡O (formaldehyde)
2. Compound B: CH3C≡O (acetaldehyde)
3. Compound C: CH3C≡OCH3 (acetone)

### Step 2: Hydrolysis of Compound A
- **Reaction**: HC≡O + H2O (in presence of H+)
- **Product**: On hydrolysis, formaldehyde will yield:
- H2C(OH)2 (a diol)
- **Analysis**: This product has two identical hydrogen atoms attached to the carbon, making it not optically active.

### Step 3: Hydrolysis of Compound B
- **Reaction**: CH3C≡O + H2O (in presence of H+)
- **Product**: On hydrolysis, acetaldehyde will yield:
- CH3C(OH)H (with an OH group and a hydrogen atom)
- **Analysis**: The product has four different groups attached to the carbon atom (CH3, OH, H, and the carbon chain), making it optically active.

### Step 4: Hydrolysis of Compound C
- **Reaction**: CH3C≡OCH3 + H2O (in presence of H+)
- **Product**: On hydrolysis, acetone will yield:
- CH3C(OH)(CH3)
- **Analysis**: This product has two identical methyl groups (CH3) attached to the carbon, making it not optically active.

### Conclusion
From the analysis, we find that only Compound B (acetaldehyde) produces an optically active product upon hydrolysis.

### Final Answer
The compound that gives an optically active product on hydrolysis is **Compound B** (CH3C≡O).

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