Question

Styrene undergoes the following sequence of reactions Molar mass of product (P) is:

• A. 104
• B. 118
• C. 132
• D. 146

Answer 1

The Correct Option is B

The given reaction sequence involves styrene undergoing a series of chemical transformations to arrive at the product \( P \). Let's analyze each step of the reaction:

1. The styrene molecule is brominated using \( \text{Br}_2/\text{CHCl}_3 \). This step adds bromine across the double bond.
2. The dibromide formed is treated with excess \( \text{NaNH}_2 \). This reagent typically causes the formation of a triple bond (an alkyne) through dehydrohalogenation.
3. The alkyne then undergoes alkylation with \( \text{CH}_3\text{I} \), adding a methyl group to the terminal carbon.
4. Finally, reduction using \( \text{H}_2/\text{Na/liq. NH}_3 \) converts the alkyne to an alkene.

We need to calculate the molar mass of the final product \( P \). Considering the transformations:

• Starting with styrene: \( \text{C}_8\text{H}_8 \) with molar mass 104 g/mol.
• Alkyne CH addition: one \( \text{C} \) and three \( \text{H} \) atoms added.
• Total expected molar mass of \( P \) = 104 + 14 = 118 g/mol.

Therefore, the molar mass of the product \( P \) is 118 g/mol, which matches with the correct option.