The formation of cyanohydrin from a ketone is an example of

Options

A. Electrophilic addition
B. Nucleophilic addition
C. Nucleophilic substitution
D. Electrophilic substitution

Explanation

To determine the type of reaction that the formation of cyanohydrin from a ketone represents, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We start with a ketone, which has the general structure R-C(=O)-R', where R and R' are hydrocarbon groups.

2. **Nucleophilic Attack**:
- The reaction involves the addition of hydrogen cyanide (HCN) to the ketone. In this reaction, the cyanide ion (CN⁻) acts as a nucleophile.
- The carbon atom of the carbonyl group (C=O) in the ketone has a partial positive charge due to the electronegativity difference between carbon and oxygen. This makes it susceptible to attack by the nucleophile (CN⁻).

3. **Formation of the Intermediate**:
- The nucleophile (CN⁻) attacks the electrophilic carbon of the carbonyl group, leading to the formation of a tetrahedral intermediate. This intermediate has the structure R-C(OH)(CN)-R'.

4. **Protonation**:
- The tetrahedral intermediate can then be protonated by an acid (like H₃O⁺), resulting in the formation of the final product, which is a cyanohydrin. The structure of the cyanohydrin is R-C(OH)(CN)-R'.

5. **Conclusion**:
- The overall process involves the addition of a nucleophile (CN⁻) to the electrophilic carbon of the ketone, which is characteristic of a nucleophilic addition reaction.

### Final Answer:
The formation of cyanohydrin from a ketone is an example of **nucleophilic addition**.

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