Bromination of Ethylene

C₂H₄ + Br₂ → C₂H₄Br₂

Overview

Ethylene reacts with bromine in an electrophilic addition reaction to form 1,2-dibromoethane. The brown color of bromine water is decolorized instantly, making this the classic qualitative test for unsaturation (C=C double bonds). The mechanism involves a cyclic bromonium ion intermediate.

Participants

Role	Substance	Coefficient	State
Reactant	Ethylene C₂H₄	1	(g)
Reactant	Bromine Br	1	(l)

Everyday Example

The bromine water test for alkenes is one of the most dramatic color-change tests in organic chemistry: brown instantly becomes colorless.

Industrial Importance

1,2-Dibromoethane was historically used as a lead scavenger in leaded gasoline and is now an important chemical intermediate.

Properties

Type: Organic
Reversible: No
Energy: Exothermic
ΔH: -121.0 kJ/mol

Related Reactions

Aldol Condensation of Acetaldehyde Amide Formation (Acetic Acid + Ammonia) Baeyer-Villiger Oxidation Beckmann Rearrangement (Cyclohexanone Oxime) Buchwald-Hartwig Amination Cannizzaro Reaction of Formaldehyde Catalytic Hydrogenation of Ethylene Claisen Condensation (Ethyl Acetate) Condensation Polymerization (Nylon 6,6) Cope Rearrangement

Frequently Asked Questions

What is the equation for Bromination of Ethylene?

The balanced equation is: C₂H₄ + Br₂ → C₂H₄Br₂.

What type of reaction is Bromination of Ethylene?

Bromination of Ethylene is a organic reaction.

Is Bromination of Ethylene exothermic or endothermic?

Bromination of Ethylene is exothermic (releases energy). The enthalpy change (ΔH) is -121.0 kJ/mol.