Terminal alkene
= Terminal alkene
A <terminal alkene> has a carbon-carbon double bond at the end of its carbon framework, commonly written $\mathrm{RCH{=}CH_2}$. The terminal carbon is a methylene group.
It differs from an internal alkene whose double-bond carbons both continue into carbon substituents. This distinction affects substitution, possible geometrical isomerism, and the regioselectivity of reactions across the double bond.