19. Reactions of Aromatics: EAS and Beyond

Predict the site(s) of electrophilic attack on these compounds.

Predict the major products formed when benzene reacts (just once) with the following reagents.

f. fuming sulfuric acid

Predict the major product(s) that would result when molecules (a)–(i) are allowed to react under the following conditions. (iv) chlorocyclopentane, AlCl₃, (v) 1-chloro-1-methylcyclohexane , AlCl₃, (vi) PhCOCl, AlCl₃. If no reaction will occur, indicate by writing NR.

(a)

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

Predict the major product of the following electrophilic aromatic substitution reactions.

(c)

Which reactions will produce the desired product in good yield? You may assume that aluminum chloride is added as a catalyst in each case. For the reactions that will not give a good yield of the desired product, predict the major products.

(e) Reagents: toluene + HNO₃, H₂SO₄, heat

Desired Product: 2,4,6-trinitrotoluene (TNT)

The nitro group directs electrophilic aromatic substitution to the meta position. After reduction by hydrogenation, to which carbon(s) does it direct?

Predict the mononitration products of the following compounds.

e. m-cresol (m-methylphenol)

Biphenyl is two benzene rings joined by a single bond. The site of substitution for a biphenyl is determined by (1) which phenyl ring is more activated (or less deactivated), and (2) which position on that ring is most reactive, using the fact that a phenyl substituent is activating and ortho, para-directing.

b. Predict the mononitration products of the following compounds

(vi)

Predict the major products of the following reactions.

(c) nitrobenzene + fuming sulfuric acid

Biphenyl is two benzene rings joined by a single bond. The site of substitution for a biphenyl is determined by (1) which phenyl ring is more activated (or less deactivated), and (2) which position on that ring is most reactive, using the fact that a phenyl substituent is activating and ortho, para-directing.

b. Predict the mononitration products of the following compounds

(v)

Despite the amino group being an ortho/para director, nitration of aniline gives the meta isomer predominantly. Explain this result.

a. Does a coupling reaction have to be used to synthesize p-dipropylbenzene?

b. Can a coupling reaction be used to synthesize p-dipropylbenzene?

Protonation of aniline slows electrophilic aromatic substitution and directs electrophiles to the meta position. Why?

Draw the resonance contributors for:

a. benzaldehyde