ORGANIC CHEMISTRY (PETRO)

ORGANIC CHEMISTRY
Dr Nam T. S. Phan
Faculty of Chemical Engineering
HCMC University of Technology
Office: room 211, B2 Building
Phone: 8647256 ext. 5681
Email:
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Chapter 8:

ARENES

Benzene

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CRITERIA FOR AROMATICITY
To be classified as aromatic, a compound must
meet both of the following criteria:
• It must have an un-interrupted cyclic π cloud
above & below the plane of the molecule
• The π cloud must contain (4n + 2) π electrons (n
= 0, 1, 2…)

un-interrupted
cyclic π cloud

6πe=4x1+2

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Aromatic:

(+)
(-)

(+)

N
H

O

S
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NOT (4n + 2) π e

NOT aromatic:

(.)

(+)
4πe

(-)

(.)

5πe

7πe

8πe

Interrupted
cyclic π
cloud
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NOMENCLATURE OF
MONOSUBSTITUTED BENZENES
Name of substituent + benzene

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Names have to be memorized:

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NOMENCLATURE OF DI- &
POLYSUBSTITUTED BENZENES

Alphabetical order, 1-position for the 1st stated substituent

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1 of the substituents can be incorporated into a name:

Names
incorporating
2 substituents
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Alphabetical
order

Lowest possible
numbers

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PREPARATION OF BENZENE

Petroleum

Bezene
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REACTIONS OF BENZENE
Halogenations of benzene

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Reaction mechanism: electrophilic substitution

Catalyst regeneration 13


Nitration of benzene

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Sulfonation of benzene

Reversible reaction
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Reaction mechanism: electrophilic substitution

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Friedel-Crafts Alkylations of benzene

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Carbocation
rearrangement

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Friedel-Crafts Acylations of benzene

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Reaction mechanism: electrophilic substitution

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Rearrangement

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REACTIONS OF SUBSTITUTED
BENZENES
Relative rates of electrophilic substitutions:

Electrondonating

Electronwithdrawing
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+I,
+C,
+H

Relative reactivity

- I,
-C,

Electron-donating

Eelectron-withdrawing

Activating

Deactivating

ortho/para-directing

meta-direcring
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