The formation of cyanohydrin from ketone is an example of :

Options

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

Answer

To determine the type of reaction involved in the formation of cyanohydrin from a ketone, 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. **Introduce the Nucleophile**:
- The nucleophile in this reaction is cyanide ion (CN⁻), which can be derived from hydrogen cyanide (HCN).

3. **Mechanism of Reaction**:
- The carbon atom in the carbonyl group (C=O) of the ketone is electrophilic due to the partial positive charge on it (δ+), while the oxygen carries a partial negative charge (δ-).
- The cyanide ion (CN⁻) attacks the electrophilic carbon atom of the carbonyl group.

4. **Formation of the Intermediate**:
- Upon the attack of CN⁻, the double bond between carbon and oxygen breaks, leading to the formation of a tetrahedral intermediate.

5. **Protonation of the Intermediate**:
- The oxygen atom in the intermediate carries a negative charge and can be protonated by a proton (H⁺) from the solution, resulting in the formation of the cyanohydrin.

6. **Final Product**:
- The final product of this reaction is a cyanohydrin, which has the structure R-C(OH)(CN)-R'.

7. **Classify the Reaction**:
- Since the cyanide ion (nucleophile) adds to the carbonyl carbon without replacing any atom, this reaction is classified as a **nucleophilic addition reaction**.

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

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