Electrophilic aromatic substitution reactions: halogenation, nitration, sulfonation, friedel-crafts acylation: (rc=o) sub. Vinylic halides and ary halides carbocations are unstable no rearrangement. Product contains a c=o group, that can complex, f/c acylations must be carried out with more than one equivalent of alcl3: water is added. Formyl cl is unstable & must be generated in situ. Gatterman koch uses high p of co and hcl formyl cl & alcl3-cucl catalyst: friedel-crafts alkylation: (r) sub. Carbocation rearrangement to most stable carbocation (hydride shift/methyl shift) Straight-chain alkyl group can be placed on a benzene ring by means of friedel-crafts acylation, followed by reduction of the carbonyl group to methylene. Do not have to use large excess of benzene. 19. 12 how some substituents on a benzene ring can be chemically changed. 19. 14 the effect of substituents on reactivity. The slow step of an eas rxn is the addition of an electrophile to the nucleophilic aromatic ring to form a carbocation intermediate.