CHM247H1 Chapter Notes - Chapter 16: Electrophilic Aromatic Substitution, Organochloride, Nitro Compound
Document Summary
16. 1 electrophilic aromatic substitution reactions: bromination: aromatic rings are less reactive towards electrophiles than alkenes, bromination of benzene takes place with a catalyst like febr3. The catalyst makes the br2 molecule more electrophilic by polarizing it: this reaction leads to a less stable carbocation, making it endergonic and slow. If addition occurred, the ring would lose its stability gained from being an aromatic compound, therefore, only substitution occurs. Aromatic fluorination, chlorination, and iodination: chlorine and iodine can be introduced with electrophilic substitution reactions, but fluorine is too reactive and gives poor yield. I2 is also not reactive enough under standard conditions and therefore not used. Aromatic nitration: aromatic rings are nitrated by a reaction with a mixture of concentrated nitric and sulfuric acids. Electrophile is the nitronium ion: nitro groups can be reduced to amines. Aromatic sulfonation: reaction uses h2so4 and so3. Note reversible reaction: forward in concentrated acid, backwards in dilute acid.
