For the preparation of `alpha` -butylene from methyl magnesium chloride, it will be reacted with

Options

A. Propene
B. Propyl chloride
C. 3–Chloro propene
D. 2–Chloro propene

Answer

To prepare alpha-butylene from methyl magnesium chloride, we need to follow a series of steps. Here’s a detailed step-by-step solution:

### Step 1: Understand the Reactants
We start with methyl magnesium chloride (CH₃MgBr), which is a Grignard reagent. Grignard reagents are highly reactive and can react with various electrophiles.

### Step 2: Identify the Desired Product
The target product is alpha-butylene, which has the structure CH₂=CH-CH₂-CH₃. This indicates that we need a four-carbon chain with a double bond between the first and second carbon atoms.

### Step 3: Choose the Electrophile
To form alpha-butylene, we need to react the Grignard reagent with an appropriate electrophile. The electrophile should be a compound that can provide the necessary carbon chain and allow for the formation of a double bond.

### Step 4: Select the Correct Electrophile
In this case, we can use 3-chloropropene (CH₂=CH-CH₂Cl) as the electrophile. The structure of 3-chloropropene is CH₂=CH-CH₂Cl, which has three carbons and a chlorine atom attached to the third carbon.

### Step 5: Mechanism of Reaction
The reaction occurs via an SN2 mechanism. The nucleophilic carbon (from the methyl group of the Grignard reagent) will attack the carbon atom bonded to the chlorine in 3-chloropropene. This will result in the displacement of the chlorine atom and the formation of a new carbon-carbon bond.

### Step 6: Write the Reaction
The reaction can be represented as follows:

\[ \text{CH}_3\text{MgBr} + \text{CH}_2=CH-CH_2\text{Cl} \rightarrow \text{CH}_2=CH-CH_2-CH_3 + \text{MgBrCl} \]

### Step 7: Conclusion
The product formed from this reaction is alpha-butylene (CH₂=CH-CH₂-CH₃), confirming that the correct electrophile to react with methyl magnesium chloride is 3-chloropropene.

### Final Answer
The correct answer is **3-Chloropropene**.

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