The reaction `: CH_3 CH_2 I + KOH ( aq) to CH_3 CH_2 OH + KI`

Options

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

Explanation

To determine the type of reaction occurring in the given equation, we will analyze the reaction step by step.

### Step 1: Identify the Reactants and Products
The reactants in this reaction are:
- Ethyl iodide (CH₃CH₂I)
- Potassium hydroxide (KOH)

The products of the reaction are:
- Ethanol (CH₃CH₂OH)
- Potassium iodide (KI)

### Step 2: Break Down the Reaction
The reaction can be written as:
\[ \text{CH}_3\text{CH}_2\text{I} + \text{KOH} \rightarrow \text{CH}_3\text{CH}_2\text{OH} + \text{KI} \]

### Step 3: Analyze the Mechanism
1. **Dissociation of KOH**: KOH dissociates in aqueous solution to give K⁺ and OH⁻ ions.
\[ \text{KOH} \rightarrow \text{K}^+ + \text{OH}^- \]

2. **Nucleophilic Attack**: The hydroxide ion (OH⁻) acts as a nucleophile and attacks the carbon atom that is bonded to the iodine in ethyl iodide (CH₃CH₂I). This is a backside attack, which is characteristic of the SN2 mechanism.

3. **Substitution**: During this attack, the iodine atom (I⁻) is displaced, leading to the formation of ethanol (CH₃CH₂OH) and potassium iodide (KI).
\[ \text{CH}_3\text{CH}_2\text{I} + \text{OH}^- \rightarrow \text{CH}_3\text{CH}_2\text{OH} + \text{I}^- \]

### Step 4: Conclusion
Since the reaction involves the substitution of one group (iodine) by another (hydroxide), and it follows the SN2 mechanism (which involves a nucleophile attacking the substrate), we conclude that this reaction is a **nucleophilic substitution reaction**.

### Final Answer
The type of reaction is **nucleophilic substitution reaction**.

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