Quiz 5-Chapter 16

What is the driving force for loosing a proton as the last step in electrophilic aromatic substitution?

to rearomatize the ring system

What is the reactive intermediate formed in the addition-elimination mechanism of nucleophilic aromatic substitution?

carboanion

What are the3 two distinct pathways for nucleophilic aromatic substitution?

Addition-elimination and elimination-addition

Which of the following substituents is a meta director?

SO3H

II < I < III < IV

What is the reactive intermediate formed in the elimination-addition mechanism of nucleophilic aromatic substitution?

Benzyne

How can polyalkylation be minimized in Friedel-Crafts alkylation?

use large excess of benzene relative to the alkyl halide

H2, Pd-C

I < II < III

none of them

III

II

II

Only III

CH3CH2C(O)Cl, AlCl3 2. HNO3, H2SO4 3. Zn(Hg), HCl

What is the electrophile in aromatic nitration?

NO2+

Which of the following substituents is a deactivator in electrophilic aromatic substitution?

(CH3)3N+

IV

Which of the following statements about the mechanism of electrophilic aromatic substitution is not true?

the transition state of the first step is lower in energy

I

II

Which of the following statements about nucleophilic aromatic substitution is true?

the elimination-addition mechanism is not as common as the addition-elimination mechanism

IV

IV

NBS and light