19. Reactions of Aromatics: EAS and Beyond

p-Xylene undergoes nitration much faster than benzene. Use resonance forms of the sigma complex to explain this accelerated rate

For each horizontal row of substituted benzenes, indicate

a. the one that is the most reactive in an electrophilic aromatic substitution reaction.

List the compounds in each set from most reactive to least reactive toward electrophilic aromatic substitution:

b. dichloromethylbenzene, difluoromethylbenzene, toluene, chloromethylbenzene

List the compounds in each set from most reactive to least reactive toward electrophilic aromatic substitution:

a. benzene, phenol, toluene, nitrobenzene, bromobenzene

Rank each group of compounds from most reactive to least reactive toward electrophilic aromatic substitution:

b. 1-chloro-2,4-dinitrobenzene, 2,4-dinitrophenol, 1-methyl-2,4-dinitrobenzene

Rank each group of compounds from most reactive to least reactive toward electrophilic aromatic substitution:

e. p-methylnitrobenzene, 2-chloro-1-methyl-4-nitrobenzene, 1-methyl-2,4-dinitrobenzene, p-chloromethylbenzene

Rank each group of compounds from most reactive to least reactive toward electrophilic aromatic substitution:

f. bromobenzene, chlorobenzene, fluorobenzene, iodobenzene

For each horizontal row of substituted benzenes, indicate

c. the one that yields the highest percentage of meta product in an electrophilic aromatic substitution reaction.

Why is anisole nitrated more rapidly than thioanisole under the same conditions?

A mixture of 0.10 mol benzene and 0.10 mol p-xylene was allowed to react with 0.10 mol nitronium ion until all the nitronium ion was gone. Two products were obtained: 0.002 mol of one and 0.098 mol of the other.

b. Why was more of one product obtained than of the other?

Indigo is a dye that was originally isolated from coal tar. In 1905, Johann Friedrich Wilhelm Adolf von Baeyer won a Nobel Prize for a method that allowed indigo to be isolated from plants [a green chemist ahead of his time.] If you nitrated indigo using the reaction learned in this chapter, at which carbon would you expect the nitro group to attach?

Substitution at the benzylic position of the molecules shown was observed to occur at different rates. Explain this observation.

Which of the following phenoxides should be a stronger nucleophile?