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Alkenes (Olefins)

CₙH₂ₙ (acyclic); R-CH=CH-R' (general)
Quick Reference
Formula / NotationCₙH₂ₙ (acyclic); R-CH=CH-R' (general)
Also Known AsOlefins; alkene hydrocarbons; unsaturated hydrocarbons (monounsaturated); CₙH₂ₙ series; ethylene (ethene)

What is Alkenes (Olefins)?

Alkenes (also called olefins) are unsaturated hydrocarbons containing at least one carbon–carbon double bond (C=C). The general formula for acyclic alkenes is CₙH₂ₙ. The simplest alkene is ethene (ethylene, CH₂=CH₂). Alkenes are more reactive than alkanes due to the π bond in the double bond, which readily undergoes addition reactions.

Formula & Notation

CₙH₂ₙ (acyclic); R-CH=CH-R' (general)

Other Names / Synonyms: Olefins; alkene hydrocarbons; unsaturated hydrocarbons (monounsaturated); CₙH₂ₙ series; ethylene (ethene)

Properties & Characteristics

General formula CₙH₂ₙ; contain C=C double bond (one σ + one π bond); planar geometry around double bond; exhibit geometric (cis/trans) isomerism; undergo electrophilic addition reactions; lighter alkenes are gases, heavier ones are liquids or solids; Markovnikov's rule for HX addition

Uses & Applications

Ethylene is the largest-volume organic chemical produced (polyethylene, PVC, ethylene glycol); propylene for polypropylene and acrylics; industrial monomers for polymers; starting materials for alcohols, aldehydes, and other organic compounds; ripening agent (ethylene gas)

Safety Information

Lower alkenes are highly flammable gases or volatile liquids. Ethylene and propylene are explosive when mixed with air in certain proportions. Some alkenes are irritants. Proper ventilation and flame precautions required. Industrial-scale alkene handling requires explosion-proof equipment.

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

Key Facts

Term Alkenes (Olefins)
Formula CₙH₂ₙ (acyclic); R-CH=CH-R' (general)
Synonyms Olefins; alkene hydrocarbons; unsaturated hydrocarbons (monounsaturated); CₙH₂ₙ series; ethylene (ethene)

Frequently Asked Questions

Alkenes (also called olefins) are unsaturated hydrocarbons containing at least one carbon–carbon double bond (C=C). The general formula for acyclic alkenes is CₙH₂ₙ. The simplest alkene is ethene (ethylene, CH₂=CH₂). Alkenes are more reactive than alkanes due to the π bond in the double bond, which readily undergoes addition reactions.

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