The addition of HCN to carbonyl compounds is an example of

Options

A. nucleophilic addition
B. electrophilic addition
C. free radical addition
D. elimination addition.

Explanation

To solve the question regarding the addition of HCN to carbonyl compounds, we will break down the process step by step.

### Step-by-Step Solution:

1. **Identify Carbonyl Compounds**:
Carbonyl compounds include aldehydes and ketones, which contain a carbonyl group (C=O).

2. **Reaction with HCN**:
When HCN (hydrogen cyanide) is added to a carbonyl compound, it dissociates into CN⁻ (cyanide ion) and H⁺ (hydrogen ion).

3. **Electrophilic Nature of Carbonyl Carbon**:
The carbon atom in the carbonyl group is electrophilic due to the partial positive charge it carries (because of the electronegativity of oxygen). This makes it susceptible to nucleophilic attack.

4. **Nucleophilic Attack**:
The cyanide ion (CN⁻), which acts as a nucleophile, attacks the electrophilic carbon atom of the carbonyl group. This results in the formation of a tetrahedral intermediate.

5. **Formation of Cyanohydrin**:
After the nucleophilic attack, the pi bond between carbon and oxygen breaks, and the oxygen atom now carries a negative charge. A proton (H⁺) from the solution then adds to this negatively charged oxygen, leading to the formation of a cyanohydrin.

6. **Final Product**:
The final product of this reaction is a cyanohydrin, which contains both a hydroxyl group (-OH) and a cyano group (-CN) attached to the same carbon atom.

7. **Conclusion**:
The addition of HCN to carbonyl compounds is classified as a **nucleophilic addition reaction** because the nucleophile (CN⁻) attacks the electrophilic carbon atom of the carbonyl group, resulting in the formation of a new bond.

### Final Answer:
The addition of HCN to carbonyl compounds is an example of **nucleophilic addition reaction**.

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