Chapter 19: Aromatic Substitution Reactions

Question 1

X2, Fe/AlBr3

With benzene

Answer 1

Electrophilic Aromatic Substitution: Halogenation

• Add one Br in place of H
• Deactivator: ortho-para director

Question 2

Cl2, AlCl3

With benzene

Answer 2

Electrophilic Aromatic Substitution: Halogenation

• Add one Br in place of H
• Deactivator: ortho-para director

Question 3

Fuming H2SO4

With benzene

Answer 3

Electrophilic Aromatic Substitution: Sulfonation

• Add HSO3 in place of H
• (with So3 Gas)
• reversible process with dilute H2SO4
• Can be a blocking group
• Two protenation steps
• Activator, ortho-para

Question 4

HNO3, H2SO4

With benzene

Answer 4

Electrophilic Aromatic Substitution: Nitration

• Add one NO2 in place of H
• Acid protenates HNO# and water leaves, forming nitronium ion (+)
• Deactivator, meta director

Question 5

Zn, HCl

With nitro-benzene

Answer 5

Reduction of Nitro group

Adds: H2 on N in place of O2

Question 6

XR, AlCl3

With benzene

Answer 6

Electrophilic Aromatic Substitution: Friedal Crafts Alkylation
Add R in place of H
-must not be primary position of halide, to limit rearrangments
-Activator, ortho-para director

Question 7

O=CX-R, AlCL3

With benzene

Answer 7

Electrophilic Aromatic Substitution: Friedal Crafts Acylation

• Add O=C-R in place of H
• Acyllium ion is resonance stabilized and can add primary carboations without rearrangement

Question 8

Zn[Hg], HCl, Heat

With Acyl-benzene

Answer 8

Clemmonson Reduction
Reduces C=O
-Can add primry alkyl chain to benzene in this way from friedal crafts acylation

Question 9

1) NaOH, Heat
2) H3O+
With halide-benzene with nitro

Answer 9

Nucleophilic Aromatic Substitution
-Changes a halide into an OH
-Ring must have nitro group
-ring must have LG
-These must be ortho or para to each other
Acid protenates the OH at the end
-forms meisenheimer complex intermediate

Question 10

1) NaOH, heat
2) H3O+
or
1)NaNH2, NH3(l)
2)H3O+
With halide-benzene

Answer 10

Elimination-Addition

• Eliminates halide and forms benzyne, and then the nuc attacks either carbon, H3O+ protenates the anionic carbon
• Nuc acts as base and nucleophile
• forms benzyne intermediate