Benzene

Question 1

Nitration
HNO3, H2SO4

Answer 1

• Meta-directing: substituent to the 1,3 position
• The groups are electron-withdrawing, destabilizing the carbocation at the ortho and para positions

Question 2

Sulfonation/Desulfonation
SO3, H2SO4

Answer 2

Meta-directing: substituent to the 1,3 position

Question 3

Halogenation
X2, FeX3

Answer 3

• Ortho/para-directing: substituent to the 1,2 and 1,4 positions
• The groups are electron-donating, either through resonance or inductive effects.
• NOTE: The halogenation of Cl also works with AlCl3 (Friedel-Crafts Reagents)

Question 4

Friedel-Crafts Alkylation
R’-X, AlCl3

Answer 4

• Favours tertiary and secondary alkylating agents due to their greater stability as carbocations

Question 5

Friedel-Crafts Acylation
RCOCl, AlCl3

Answer 5

Question 6

Clemmensen Reduction
Zn(Hg), HCl

Answer 6

• Not limited to aromatics

Question 7

Wolff-Kishner
H2 NNH2, KOH, Heat

Answer 7

• Not limited to aromatics

Question 8

Side-Chain Oxidation
1) KMnO4, Heat, H2O 2) H3O+

Answer 8

Question 9

Intramolecular Friedel-Crafts

Answer 9

• The reaction is favoured when the distance between the electrophilic center and the aromatic ring is within a range conducive to forming a 5- or 6-membered ring

Question 10

Catalytic Hydrogenation of Ring

Answer 10

• Removes all the double bonds from the ring

Question 11

Birch Reduction
Na, NH3, Ethanol

Answer 11

Question 12

Benzylic Radical Halogenation

Answer 12

• Prefers the secondary position

Question 13

Benzylic Substitution/Elimination

Answer 13

• SN1 or SN2 reactions
• SN1: Favored by tertiary or benzylic substrates, good leaving groups, polar protic solvents, and nonbasic nucleophiles
• SN2: Strong nucleophiles, a good leaving group, a relatively unhindered electrophilic center (primary or methyl), and a polar aprotic solvent