CHEMISTRY · Multi-part · A Level · Chemistry · Introduction to organic chemistry · Introduction to organic chemistry
Problem
The allyl radical, C₃H₅•, is an important intermediate in combustion chemistry. The carbon skeleton is H₂C═CH–CH₂•, where the dot indicates an unpaired electron.
(a) Determine the total number of valence electrons that must be shown in a complete set of Lewis resonance structures for the allyl radical.
(b) Draw all significant resonance contributors for the allyl radical, clearly indicating the position of the unpaired electron in each contributor.
(c) Assign formal charges to every atom in each resonance contributor drawn in part (b).
(d) Using your resonance and formal-charge analysis, explain how electron delocalization stabilizes the allyl radical and predict which carbon atom is most electron-deficient in the overall resonance hybrid.