Chapter 17: Aromatic Compounds

Question 1

Answer 1

Toluene

Question 2

Answer 2

Phenol

Question 3

Answer 3

Anisole

Question 4

Answer 4

Aniline

Question 5

Answer 5

Benzoic Acid

Question 6

Answer 6

Benzaldehyde

Question 7

Answer 7

Acetophenone

Question 8

Answer 8

Styrene

Question 9

Answer 9

Chlorobenzene

Question 10

Answer 10

Nitrobenzene

Question 11

Answer 11

Ethylbenzene

Question 12

Answer 12

ortho-Xylene

(1,2-dimethylbenzene)

Question 13

Answer 13

meta-Xylene

(1,3-dimethylbenzene)

Question 14

Answer 14

para-Xylene

(1,4-dimethylbenzene)

Question 15

Answer 15

ortho-Nitroanisole

(2-nitroanisole)

Question 16

Answer 16

meta-Bromotoluene

(3-bromotoluene)

Question 17

Answer 17

para-Chlorobenzaldehyde

(4-chlorobenzaldehyde)

Question 18

Criteria for aromaticity

Answer 18

1. Fully conjugated ring with overlapping p orbitals
2. Follow **Hückel’s rule-**: *odd* number of electron pairs with 4*n*+2 π electrons
3. Adopt a planar configuration

Any ring that is not conjugated is just *cyclic*

Question 19

Benzylic position

Answer 19

Any carbon atom attached directly to a benzene ring

α to the ring

Question 20

Alkylbenzene oxidation

Answer 20

Reagent

Na₂Cr₂O₇ (sodium dichromate) & H₂SO₄, H₂O

or

1. KMnO₄ (potassium permanganate) , H₂O, heat
2. H₃O⁺

Mechanism

Replaces alkyl group with a benzylic carboxy group converting the compound into a benzoic acid regardless of alkyl group

Does NOT work if the benzylic position is quaternary

Question 21

Radical bromination

Alkylbenzenes

Answer 21

Reagents

NBS & heat

Mechanism

Free-radical bromination occurs readily at the benzylic position due to the resonance stabilization of the intermediate benzylic radical

Question 22

Substitution Reactions

Alkylbenzenes

Answer 22

Benzylic bromides can undergo S_N1 reactions if sterically hindered such as tertiary alkylhalides

Can also do S_N2 reactions when unhindered such as primary

Question 23

Elimination Reactions

Alkylbenzenes

Answer 23

Benzylic bromides can undergo elimination reactions

Question 24

Birch Reduction

Answer 24

Reagents

Na(s), MeOH & NH₃

Mechanism

Will selectively reduce sp² carbons on opposite sides of a benzene ring to sp³

Will similarly reduce alkylbenzens but it will NOT reduce the carbon atom connected to the alkyl group due to electron-donating effects

WILL reduced carbon atom connected to an electron-withdrawing group such as a carbonyl group