Alkenes
Alkenes (or olefins) are hydrocarbons with at least one double bond between carbons. The double bond makes the molecule more reactive than an alkane — it's the starting point for addition reactions (halogenation, hydration, polymerization).
General formula
CnH2n (one double bond)
Naming rule
Name = numerical prefix + infix -en- + suffix -e, with the double bond's locant before the name (e.g., but-1-ene). Chain numbering starts from the end that gives the lowest locant to the double bond.
Examples
| Name | Formula |
|---|---|
| Ethene (ethylene) | C₂H₄ |
| Propene | C₃H₆ |
| But-1-ene | C₄H₈ |
| But-2-ene | C₄H₈ |
| Buta-1,3-diene | C₄H₆, 2 double bonds |