CHEM 3410 Lecture Notes - Lecture 1: Ultraviolet–Visible Spectroscopy, Electrophilic Addition, Allyl Group
Document Summary
Compounds that have alternating double and single bonds. Conjugated dienes are more stable because their electrons are delocalized. They are also more stable because of their closer bond at the central carbon-carbon bond due to their sp2 hybridization. Conjugated dienes can be prepared by elimination of hx from an allylic halide. The most striking difference between conjugated and nonconjugated alkenes is the way it reacts in an electrophilic addition. Normal alkenes follow markovnikov"s rule and rearranges to make the most stable carbocation. In a conjugated diene, there are several places in which the double bonds are and can react. With each area, there can be a resonance. With resonance, the carbocation rearrangements can double, thus having many more products. Strategy: protonate both ends of diene, draw resonance structures. Below or at room temperature, the 1,2 addition reaction is favored. Kinetic control: the product of an irreversible reaction depends only on relative rates, but not stability.
