Presentation on theme: "Side chain It’s the aliphatic portion of the alkenylbenzene."— Presentation transcript:
Side chain It’s the aliphatic portion of the alkenylbenzene.
Benzylic Radicals and Cations Benzyl radical: is a specific name for the radical produces from the Hydrogen abstraction from the methyl group of methylbenzene (tolune).
Benzylic Radicals and Cations Benzylic radical: is the general name applies to all radicals that have unpaired electron on the side- chain carbon atom that attached directely to the benzene ring.
Benzylic Radicals and Cations Benzylic hydrogen atoms: is the hydrogen atom of the carbon atom that directly attached to the benzene ring.
Benzylic Radicals and Cations Benzylic cation: is the departure of a leaving group (LG) from a benzylic position.
Benzylic Radicals and Cations They have approximately the same stabilities, this stability can be explained by resonance theory.
Halogenation of the side chain Side- chain halogenationRing halogenation It take place when the reaction is carried out in the absence of lewis acid and under condition that favor the formation of the radicals. The halogens dissociate to produce halogen atoms and then halogen atoms initiate chain reaction by abstracting hydrogens of the methyl group. The electrophiles are positive chlorin or bromine ion or they are lewis acid complexes that have positive halogen. These positive electrophiles attack the ∏ electron of the benzene ring, the aromatic substitution takes place.