History of Benzene1824 - 1825 Isolated from burnt whale oil by Michael Faraday1834 Eilhardt Mitscherlich finds benzene has formula of C6H6

1861 Loschmidt proposes structure for benzoic acid and aniline

History of Benzene1824 - 1825 Isolated from burnt whale oil by Michael Faraday1834 Eilhardt Mitscherlich finds benzene has formula of C6H6

1861 Loschmidt proposes structure for benzoic acid and aniline

O

OH

N

H

H

History of Benzene1865 Kekule has a dream1865 Kekule invokes sausage diagramsBulletin de la Société Chimique de France, 3, 98 (1865)

10–4

History of Benzene1865 Kekule has a dream1865 Kekule invokes sausage diagramsBulletin de la Société Chimique de France, 3, 98 (1865)

1866 Kekule introduces ring model for benzene

Alternate Benzene Structures

Dewar 18671972

proposedsynthesized

Landenburg Prismane

18691973

Claus18671967

Fig. 15-2, p. 521

Hückel’s Rules for aromaticity

p. 521

H

H

H

H

H

H

Benzene electron distribution map

Fig. 15-12, p. 532

Hückel’s Rules for aromaticity

Aromaticity vs. antiaromaticity

p. 523

p. 524

Hückel’s Rules for aromaticity

Aromaticity vs. antiaromaticity

Why 4n + 2 for aromatic and 4n for antiaromatic?Frost’s cycle

Fig. 15-3, p. 522

Benzene Molecular Orbitals

Cyclopentadienyl ions

Fig. 15-11, p. 531

H H H

Fig. 15-5, p. 526

Fig. 15-7, p. 527

Fig. 15-9a, p. 529

Fig. 15-9b, p. 529

17%

27%

57% A. Aromatic

B. Antiaromatic

C. Neither

5. 14-annulene

NN

OCH3CH3O

Pyridyl DHA Targets

NN

OCH3CH3O

N

N

OCH3CH3O

NN

OCH3CH3O1+2 1+2 1+0, 1+2 none 1+0 1+0

N

N

CH3O OCH3

N

N

CH3O OCH3

N

N

CH3O OCH3

N

N

CH3O OCH3

2+1 1+1 2+0, 2+1 none none 1+0, 1+1 2+0 1+0

Fig. 15-14, p. 535

p. 535

p. 540

p. 535

TIPSTIPS

Br Br

19 11

Aromatic Biomolecules

1.Amino acids2.Nucleic acids

Fig. 15-8, p. 528

Fig. 15-9, p. 529

p. 533

p. 529

p. 533

p. 530

p. 540

p. 541

p. 337

p. 338

Table 9-2, p. 337

Summary

-H (unsubstituted)

-R or -Ar, ortho- and para- -R or -Ar, meta-

-NH2 or -OH, meta-

-NH2 or -OH, ortho- and para-

-Cl or -Br, ortho- and para-

-Cl or -Br, meta-

-NO2 or -CO2H, meta-

-NO2 or -CO2H, ortho- and para-

Deactivators

Activators

Reactants

[CarbocationIntermediate]

Reaction Progress

Energy

Fig. 9-16, p. 338

p. 340

p. 345