Problem 1
Step 2 of the iodination of benzene shows water acting as a base and removing a proton from the sigma complex. We did not consider the possibility of water acting as a nucleophile and attacking the carbocation, as in an electrophilic addition to an alkene. Draw the reaction that would occur if water reacted as a nucleophile and added to the carbocation. Explain why this type of addition is rarely observed.
Problem 2
Propose a mechanism for the aluminum chloride–catalyzed reaction of benzene with chlorine.
Problem 3
p-Xylene undergoes nitration much faster than benzene. Use resonance forms of the sigma complex to explain this accelerated rate
Problem 5b
(b) Explain why m-xylene undergoes nitration 100 times faster than p-xylene.
Problem 6
Styrene (vinylbenzene) undergoes electrophilic aromatic substitution much faster than benzene, and the products are found to be primarily ortho- and para-substituted styrenes. Use resonance forms of the intermediates to explain these results.
Problem 7
Propose a mechanism for the bromination of ethoxybenzene to give o- and p-bromoethoxybenzene.
Ch. 17 - Reactions of Aromatic Compounds