1-4-17
Ch.9
* Benzene and its Derivatives
C6H6 Not double – single – double – etc
Does not do alkene reactions
All C – C bonds are ~ 1.5 bonds
All C are sp2
All have p orbitals
Forms π bonds
O–O
C–C
O–O
*
Benzene Naphthalene Anthracene
,* Aromatic compounds
Aromaticity: unusual stability like benzene
Hacked: criteria for aromaticity
- Be a closed loop (ring)
- Every atom in the ring must have a p orbital
- Must be planar (flat) or nearly flat
- Must have 4n + 2 π electrons where n = 0, 1, 2, 3, etc (2, 6, 10, 14, etc)
Double bond = 2 π electrons 10 π e-
Total: 6 π e- Is aromatic
Is aromatic
4 π e-
Not aromatic 8 π e-
Not aromatic
,* H 6 π e- in loop
H H
H H
N not in loop
Pyridine
N N N
H H H
6 π e-
4 from double bond + 2 from lone pair
Is aromatic
*
O O O
In loop out loop 6 π e- in loop
, *
B B
H H
Empty p orbital 4 π e-
2 π e- Not aromatic
Is aromatic
*
H
Empty p orbital
2 π e-
Is aromatic
H
6 π e-
Is aromatic
Ch.9
* Benzene and its Derivatives
C6H6 Not double – single – double – etc
Does not do alkene reactions
All C – C bonds are ~ 1.5 bonds
All C are sp2
All have p orbitals
Forms π bonds
O–O
C–C
O–O
*
Benzene Naphthalene Anthracene
,* Aromatic compounds
Aromaticity: unusual stability like benzene
Hacked: criteria for aromaticity
- Be a closed loop (ring)
- Every atom in the ring must have a p orbital
- Must be planar (flat) or nearly flat
- Must have 4n + 2 π electrons where n = 0, 1, 2, 3, etc (2, 6, 10, 14, etc)
Double bond = 2 π electrons 10 π e-
Total: 6 π e- Is aromatic
Is aromatic
4 π e-
Not aromatic 8 π e-
Not aromatic
,* H 6 π e- in loop
H H
H H
N not in loop
Pyridine
N N N
H H H
6 π e-
4 from double bond + 2 from lone pair
Is aromatic
*
O O O
In loop out loop 6 π e- in loop
, *
B B
H H
Empty p orbital 4 π e-
2 π e- Not aromatic
Is aromatic
*
H
Empty p orbital
2 π e-
Is aromatic
H
6 π e-
Is aromatic
