Exam 16: Chemistry of Benzene: Electrophilic Aromatic Substitution

Exhibit 16-2 Consider the Friedel-Crafts alkylation reaction below to answer the following question(s): -Refer to Exhibit 16-2.Write the complete stepwise mechanism for this reaction.Show all electron flow with arrows and include all intermediate structures.

Which of the following is an ortho- and para- director and a deactivator?

Exhibit 16-7 Consider the reaction below to answer the following question(s). -Refer to Exhibit 16-7.The Lewis acid catalyst in the reaction is:

Which of the following could successfully undergo a Friedel-Crafts alkylation? Assume an appropriate catalyst.

Exhibit 16-7 Consider the reaction below to answer the following question(s). -Refer to Exhibit 16-7.The nucleophile in the reaction is:

Exhibit 16-1 MATCH a structure or term from the following list with each description below.Place the letter of the structure or term in the blank to the left of the description. -______ Groups which activate aromatic rings towards nucleophilic substitution.

Exhibit 16-1 MATCH a structure or term from the following list with each description below.Place the letter of the structure or term in the blank to the left of the description. -__________Source of F⁺ in fluorination reactions.

The following reaction proceeds by an intramolecular nucleophilic aromatic substitution mechanism.Write the complete stepwise mechanism,showing all intermediate structures and all electron flow with arrows.

Exhibit 16-3 Consider the data below to answer the following question(s). The −NH₂ group is listed in our textbook as the strongest o,p-directing activator in electrophilic aromatic substitution reactions.However,when aniline is subjected to standard nitration conditions poor yields of m-nitroaniline result. -Refer to Exhibit 16-3.Clearly,the reaction conditions are influencing the directing effect of the −NH₂ group.Explain why this occurs,using both words and structures.

Tetracyclone is often used to trap benzynes as Diels-Alder adducts.What is the structure of the Diels-Alder adduct that results when benzyne is trapped by tetracyclone?

Exhibit 16-6 To answer the following question(s),refer to the data below: Isobutylbenzene is the starting material for the industrial synthesis of the NSAID,ibuprofen. -Refer to Exhibit 16-6.Propose a synthesis for isobutylbenzene which avoids the problems of direct Friedel-Crafts alkylation.

Exhibit 16-1 MATCH a structure or term from the following list with each description below.Place the letter of the structure or term in the blank to the left of the description. -______ Intermediate in the elimination-addition mechanism of nucleophilic aromatic substitution.

Arrange the following compounds in order of increasing reactivity to electrophilic aromatic substitution. bromobenzene nitrobenzene benzene phenol

Which of the following is a meta-deactivating group?

Exhibit 16-3 Consider the data below to answer the following question(s). The −NH₂ group is listed in our textbook as the strongest o,p-directing activator in electrophilic aromatic substitution reactions.However,when aniline is subjected to standard nitration conditions poor yields of m-nitroaniline result. -Refer to Exhibit 16-3.Draw all the resonance forms of aniline showing the electron-donating effect of the −NH₂ substituent.

Exhibit 16-4 Consider the reaction below to answer the following question(s). -Refer to Exhibit 16-4.Write the complete stepwise mechanism for the formation of the ortho product.Show all intermediate structures and show all electron flow with arrows.

Exhibit 16-1 MATCH a structure or term from the following list with each description below.Place the letter of the structure or term in the blank to the left of the description. -______ The reactive electrophile in Friedel-Crafts acylation reactions.

Would you expect (nitromethyl)benzene to be more reactive or less reactive than toluene toward electrophilic substitution? Explain.

Exhibit 16-4 Consider the reaction below to answer the following question(s). -Refer to Exhibit 16-4.Draw resonance structures for the intermediate carbocation that explain the directing effect of the −Br.

Aniline reacts with nitrous acid,HNO₂,to yield a stable diazonium salt.This diazonium salt undergoes electrophilic aromatic substitution on activated aromatic rings to yield brightly colored azo compounds that are widely used as dyes.The intermediate structures for the mechanism of this reaction are given below.Show all electron flow with arrows for this mechanism on the structures provided.