The reaction of acetaldehyde with HCN followed by hydrolysis gives a product which exhibits

Options

A. Optical isomerism
B. Geometrical isomerism
C. Metamerism
D. Tautomerism

Answer

To solve the question regarding the reaction of acetaldehyde with HCN followed by hydrolysis, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**: The reactants are acetaldehyde (CH₃CHO) and hydrogen cyanide (HCN).

2. **Reaction Mechanism**: The reaction of acetaldehyde with HCN involves a nucleophilic addition. The cyanide ion (CN⁻) acts as a nucleophile and attacks the carbonyl carbon of acetaldehyde.

3. **Formation of Cyanohydrin**:
- The nucleophilic attack leads to the formation of a cyanohydrin. The structure of the cyanohydrin can be represented as:
\[ CH₃-CH(OH)-CN \]
- Here, the hydroxyl group (OH) and the cyanide group (CN) are attached to the same carbon atom.

4. **Hydrolysis of Cyanohydrin**:
- When the cyanohydrin undergoes hydrolysis, it reacts with water to convert the cyanide group into a carboxylic acid group (COOH). The hydrolysis can be represented as:
\[ CH₃-CH(OH)-CN + H₂O \rightarrow CH₃-CH(OH)-COOH \]
- The product formed is lactic acid (2-hydroxypropanoic acid).

5. **Identify Isomerism**:
- The product, lactic acid, has a chiral center at the carbon atom bonded to the hydroxyl group (OH) and the carboxylic acid (COOH).
- This means lactic acid can exist in two enantiomeric forms (D and L forms), which are non-superimposable mirror images of each other.

6. **Conclusion**:
- Since lactic acid exhibits optical isomerism due to the presence of a chiral center, the final answer to the question is that the product exhibits **optical isomerism**.

### Final Answer:
The product exhibits **optical isomerism**.

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