Allylic systems participate in chemical reactions distinctly from non-allylic systems mainly due to the presence of resonance stabilization. The allylic position, which is the carbon atom adjacent to a double bond, has a p-orbital that overlaps with the π-orbitals of the double bond, allowing delocalization of electrons. This delocalization can stabilize carbocation, radical, or anion intermediates formed during a reaction, often leading to increased reactivity and selectivity at the allylic position.
Allylic systems are prone to nucleophilic substitution reactions and unique reactions such as allylic oxidations, which do not occur as readily with saturated carbons.