Butanenitrile may be prepared by heating

Options

A. propyl alcohol with KCN
B. butyl chloride with KCN
C. butyl alcohol with KCN
D. propyl chloride with KCN

Explanation

To prepare butanenitrile, we need to identify the correct reactants and the reaction mechanism involved. Let's break down the steps to arrive at the solution:

### Step-by-Step Solution

1. **Identify the Structure of Butanenitrile**:
- Butanenitrile has the molecular formula \( \text{C}_4\text{H}_7\text{N} \) or structurally, it can be represented as \( \text{CH}_3\text{CH}_2\text{CH}_2\text{CN} \). This indicates that it consists of a four-carbon chain with a nitrile group (\(-C \equiv N\)).

2. **Analyze the Options**:
- The options provided are:
1. Propyl alcohol with casein
2. Butyl chloride with casein
3. Butyl alcohol with casein
4. Propyl chloride with casein

3. **Determine the Role of Casein**:
- Casein is a source of cyanide ions (\( \text{CN}^- \)), which will act as a nucleophile in the reaction.

4. **Evaluate Each Option**:
- **Option 1: Propyl alcohol with casein**:
- Propyl alcohol (\( \text{C}_3\text{H}_7\text{OH} \)) would not work well because the hydroxyl group (\(-OH\)) is a poor leaving group compared to a halide.

- **Option 2: Butyl chloride with casein**:
- Butyl chloride (\( \text{C}_4\text{H}_9\text{Cl} \)) could potentially yield butanenitrile, but we need to consider the nucleophilic substitution mechanism.

- **Option 3: Butyl alcohol with casein**:
- Similar to propyl alcohol, butyl alcohol (\( \text{C}_4\text{H}_9\text{OH} \)) has an -OH group that is not a good leaving group.

- **Option 4: Propyl chloride with casein**:
- Propyl chloride (\( \text{C}_3\text{H}_7\text{Cl} \)) can react with the cyanide ion from casein. The chloride ion is a good leaving group, allowing for a nucleophilic substitution reaction to occur.

5. **Select the Correct Option**:
- The best choice is **Option 4: Propyl chloride with casein**. In this reaction, the cyanide ion will attack the carbon attached to the chlorine in propyl chloride, leading to the formation of butanenitrile.

### Final Answer:
Butanenitrile may be prepared by heating **propyl chloride with casein**.

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