19. Reactions of Aromatics: EAS and Beyond

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

Predict the products (if any) of the following reactions.

b. (excess) toluene + butan-1-ol + BF₃

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.

3.

Predict the products of the following electrophilic aromatic substitution reactions.

(b)

Predict the product(s) of the following reactions.

(d)

Predict the product of the following Friedel–Crafts acylation reactions.

(b)

Are the following substituents ortho–para directors or meta directors?

d. COOH

e. CF₃

f. N=O

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.

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

d. bromine + a nail

Give the products, if any, of each of the following reactions:

a. benzonitrile + methyl chloride + AlCl₃

b. phenol + Br₂

Predict the products formed when m-cresol (m-methylphenol) reacts with

(c) bromine in CCl₄ in the dark

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.

(d) Reagents: benzamide (PhCONH₂) + CH₃CH₂Cl

Desired Product: p-ethylbenzamide

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.

a. Use resonance forms of a sigma complex to show why a phenyl substituent should be ortho, para-directing.

(i)

Rank the following compounds from most reactive to least reactive in an electrophilic aromatic substitution reaction: