Why are they not CC

1
Why are they not CC?

• Conjugation in the ring allows the p orbitals to
  bond in a lower energy way.

Not this way, which makes C C
2
Why are they not CC?

• Conjugation in the ring allows the p orbitals to
  bond in a lower energy way.

But all around the ring which makes a low energy
total ring bond.
3
All Aromatic Compounds

• Low energy takes a lot of energy to
• break the p bond

4
Nomenclature of Aromatics

• Benzene is the simplest aromatic compound

C6H6
Aromatic rings do not behave like they have
double bonds.
5
Nomenclature of Benzene Derivatives

• Benzene

H H
H H H
H
C C C C C
C
Remember, the lines indicate C and H.
6
Nomenclature of Benzene Derivatives

• Benzene can be substituted.

Cl
Cl
Br
chlorobenzene
1-bromo-3-chlorobenzene
7
Nomenclature of Benzene Derivatives

• Some have common names.

OH
CH3
phenol
toluene
8
Nomenclature of Benzene Derivatives

• Some have common names.

O COH
NH2
benzoic acid
aniline
9
Nomenclature of Benzene Derivatives

• To name benzene derived compounds, name and
  number the substituents.
• The substituent with the higher mass has priority.

Cl
(CH3)2CH CH2CH3
CH3
1-isopropyl-3-ethylbenzene
3-chlorotoluene
10
Aromatic Nomenclature

• A common system can be used for disubstituted
  benzenes.

CH3
CH3
CH3
CH3
CH3
CH3
ortho meta
para
11
Aromatic Nomenclature
CH2CH3
OH
CH3
Cl
CH2CH3
CH2CH3
o-chlorotoluene
m-ethylphenol
p-diethylbenzene
12
Aromatic Substituents

• On larger compounds, benzene rings are
  substituents

CH2
phenyl
benzyl
A general symbol for an aromatic substituent is
-Ar
13
You try it!

• Name these compounds both ways.

NH2
Cl
OH
CH2CH3
Br
Cl
14
You draw it!

• 2,6-dichlorotoluene
• p-bromophenol