Halogenation — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Q: What is the formula for Halogenation?

The formula or notation for Halogenation is: C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway

Formula / Notation	C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway
Also Known As	Chlorination, bromination, fluorination, iodination (specific halogens)

What is Halogenation?

A reaction in which halogen atoms are introduced into a molecule. Halogenation of alkanes (radical mechanism) requires UV light or heat. Halogenation of alkenes (electrophilic addition) occurs without light. Used to synthesize pharmaceuticals, pesticides, and flame retardants.

Formula & Notation

C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway

Other Names / Synonyms: Chlorination, bromination, fluorination, iodination (specific halogens)

Properties & Characteristics

Halogenation is the introduction of one or more halogen atoms into a molecule. In alkanes, radical halogenation (initiated by UV light or heat) produces alkyl halides via a chain mechanism. In aromatic compounds, electrophilic halogenation requires a Lewis acid catalyst (AlCl₃, FeBr₃) to generate a halogen electrophile (Cl⁺, Br⁺ equivalent) for EAS. Fluorination is too violent for direct use; iodination often requires an oxidant.

Uses & Applications

Halogenation is industrially important in producing: chloromethanes (solvents, precursors), brominated flame retardants, polyvinyl chloride (PVC from vinyl chloride), pharmaceutical intermediates (fluorinated drugs), and agrochemicals. Selective halogenation at specific sites is a key challenge in synthesis.

Safety Information

Halogenating agents (Cl₂, Br₂, NBS, SO₂Cl₂, PCl₅) are toxic, corrosive, and/or oxidising. HX by-products are acidic and corrosive. Radical halogenation with Cl₂ in sunlight can ignite explosively. All halogenation reactions require fume hoods and appropriate gas scrubbing.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Halogenation

Formula C-X + Cl₂/Br₂ (hv or AlCl₃) → C-X(halogen); EAS or radical pathway

Index All "H" terms

Synonyms Chlorination, bromination, fluorination, iodination (specific halogens)

Frequently Asked Questions

What is Halogenation?

A reaction in which halogen atoms are introduced into a molecule. Halogenation of alkanes (radical mechanism) requires UV light or heat. Halogenation of alkenes (electrophilic addition) occurs without light. Used to synthesize pharmaceuticals, pesticides, and flame retardants.

What is Halogenation used for?

Is Halogenation hazardous?

What is the formula for Halogenation?

More "H" Terms

Haber Process N₂ + 3H₂ ⇌ 2NH₃ | ΔH = −92 kJ/mol Hafnium Hf Half Cell Half Life Half-Cell E = E° − (RT/nF)lnQ Half-Life A(t) = A₀e^(−λt); t½ = ln2/λ Half-Reaction Halide X⁻ (e.g., F⁻, Cl⁻, Br⁻, I⁻) Halogen F₂, Cl₂, Br₂, I₂, At; Group 17; ns²np⁵ valence configuration Halogens Hard Acid Hard acid: small, highly charged, low polarisability (e.g., H⁺, Mg²⁺, Al³⁺) Hard Base Hard base: high EN, low polarisability (e.g., F⁻, OH⁻, NH₃, H₂O)

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