Target Exam

CUET

Subject

Chemistry

Chapter

Organic: Haloalkanes and Haloarenes

Question:

Propene on addition with bromine in $CCl_4$ gives

Options:

1,2-Dibromopropane

2,2-Dibromopropane

Propylbromide

2-Bromopropane

Correct Answer:

1,2-Dibromopropane

Explanation:

The correct answer is Option (1) → 1,2-Dibromopropane

Core Concept:

Bromine adds across double bond in nonpolar solvent via electrophilic addition.

Explanation:

When propene reacts with bromine in CCl₄, bromine undergoes electrophilic addition across the double bond. The π-bond breaks and each carbon forms a bond with bromine, resulting in vicinal dibromide formation.

This reaction proceeds via bromonium ion intermediate and results in addition of Br to both carbons of the double bond.

Thus:

 

Option 1: 1,2-Dibromopropane

Correct because bromine adds across the double bond.

Option 2: 2,2-Dibromopropane

Incorrect because addition is across both carbons, not geminal.

Option 3: Propyl bromide

Incorrect because this would require substitution.

Option 4: 2-Bromopropane

Incorrect because this would require HBr addition.