The formation of cyanohydrin from a ketone is an example of

Options

A. electrophilic addition
B. nucleophilic addition
C. nucleophilic substitution
D. electrophilic substitution

Answer

To solve the question regarding the formation of cyanohydrin from a ketone, we will break down the process step by step.

### Step-by-Step Solution:

1. **Identify the Reaction Type**: The formation of cyanohydrin from a ketone is an example of a nucleophilic addition reaction. In this type of reaction, a nucleophile attacks an electrophilic carbon atom.

2. **Select a Ketone Example**: We can use acetone (CH₃COCH₃) as our example of a ketone. Acetone has a carbonyl group (C=O) which is susceptible to nucleophilic attack.

3. **Introduce the Nucleophile**: The nucleophile in this reaction is the cyanide ion (CN⁻), which can be generated from hydrogen cyanide (HCN). HCN is a weak acid and can partially dissociate into H⁺ and CN⁻ in solution.

4. **Nucleophilic Attack**: The cyanide ion (CN⁻) attacks the electrophilic carbon atom of the carbonyl group in acetone. This results in the breaking of the π bond of the carbonyl, leading to the formation of a tetrahedral intermediate.

5. **Formation of the Intermediate**: The attack of the cyanide ion on the carbonyl carbon results in the formation of an alkoxide intermediate. The structure now has a negatively charged oxygen atom (O⁻) and the cyanide group (CN) attached to the carbon.

6. **Protonation of the Alkoxide**: To convert the alkoxide intermediate into the final product, water (or H⁺ from HCN) is used to protonate the negatively charged oxygen atom. This results in the formation of the hydroxyl group (OH).

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

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

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