Organic Chemistry I:CHEM 2211

Chapter 17

Aromaticity

Chapter 17 Problem Set

17.1-17.4, 17.6-17.18, 17.20-23 (in chapter, help to understand materials);

17.24-69

I do recommend more practice to everyone. Please do all the book questions as much as you can.

Keys for this chapter

• Nomenclature (easy!);

• Aromaticity (energy as the driving force);

• Reactivity at the benzylic position (most from Org-I)

17.1 Introduction of aromatic compounds

N

14.2 Nomenclature: functional group and position

F

fluorobenzene

NO2

nitrobenzene

CH3

toluene

OH

phenol

NH2

aniline

17.2 Nomenclature: functional group and position

o-xylene m-xylene p-xylene

17.2 Nomenclature: functional group and position

O2N

Br

COOH

3-bromo-5-nitrobenzoic acid

Br1-(3-bromo-5-(tert-butyl)phenyl)ethan-1-one

O

17.3 Structure of benzene: the self-bitting snake

17.3 Reactivity: too stable to be a simple C=C!

Improved stability

+ H2

HH

ΔHo = -120 kJ/mol

+ H2

HH

ΔHo = -232 kJ/mol2H

H

+ H2

HH

ΔHo = -208 kJ/mol3H

H

H

H

17.5 Aromaticity

• Cyclic

• Conjugate

• Planner

• 4n+2

Aromatic, anti-aromatic and non-aromatic

• Cyclic

• Conjugate

• Planner• 4n+2

Hetero-Aromatic compounds

N NH

N N

Other weird cases Aromatic compounds

17.6 Reaction at benzylic positions