Question

Identify the starting compound \(P\) in the following reaction.

• A. 1-Bromo-2-methylpropane
• B. 1-Bromobutane
• C. 2-Bromopropene
• D. 2-Bromobutane

Hint:

In Wurtz reaction, identify the alkyl halide by splitting the product at the newly formed central C-C bond. Each half corresponds to the alkyl group of the original alkyl halide.

Answer 1

The Correct Option is A

Step 1: Identify the reaction type.
The reagent used is \[ Na/\text{dry ether} \] which indicates the

Wurtz reaction.
In a Wurtz reaction, two molecules of an alkyl halide couple together: \[ 2R-X + 2Na \rightarrow R-R + 2NaX \]

Step 2: Analyze the product formed.
The product is \[ (CH_3)_2CHCH_2CH_2CH(CH_3)_2 \] This can be written as \[ (CH_3)_2CH-CH_2-CH_2-CH(CH_3)_2 \] The molecule is symmetrical about the central \[ -CH_2-CH_2- \] unit.

Step 3: Split the product into two identical halves.
Breaking the central carbon-carbon bond gives \[ (CH_3)_2CHCH_2- \] and \[ -CH_2CH(CH_3)_2 \] Thus, each alkyl fragment is \[ (CH_3)_2CHCH_2- \] which is the

isobutyl group.

Step 4: Determine the corresponding alkyl halide.
The alkyl halide that produces the isobutyl group is \[ (CH_3)_2CHCH_2Br \] whose IUPAC name is 1-Bromo-2-methylpropane On Wurtz coupling: \[ 2(CH_3)_2CHCH_2Br \xrightarrow[dry\ ether]{2Na} (CH_3)_2CHCH_2CH_2CH(CH_3)_2 +2NaBr \] which matches the given product.

Step 5: Final conclusion.
Therefore, the starting compound \(P\) is \[ \boxed{\text{1-Bromo-2-methylpropane}} \] Hence, option (1) is correct.