Ring Current in Benzene

1
SOME NMR PROBLEMS
2
An ester -- C4H8O2
1
3
Monosubstituted Aromatic Hydrocarbon -- C9H12
2
4
Carboxylic Acid - C4H7O2Br
3
10.97 ppm
5
Ester derived from acetic acid (C5H10O2)
4
2.5 / 3 0.83
6
Ester derived from acetic acid (C5H10O2)
5
1 3 6
7
C3H6Br2
6
2 1
8
C8H12O4
7
(IR shows strong band at 977 cm-1)
9
C5H10O2
8
a,b triplets c,d quartets
10
C5H7NO2
9
a triplet b singlet c quartet
11
C4H8O
10
b
a
a triplet b singlet c quartet
c
12
C6H12O2
11
a
b
a,b singlets
13
C8H8O2
12
c
a
b
a,c singlets
b unresolved multiplet
14
C5H12O
13
a
b
c
d
e
a doublet, b quartet, c nonet, d
singlet, e triplet
15
CORRELATION CHARTS
16
NMR Correlation Chart
-OH
-NH
DOWNFIELD
UPFIELD
DESHIELDED
SHIELDED
CHCl3 ,
TMS
d (ppm)
12
11
10
9
8
7
6
5
4
3
2
1
0
H
CH2Ar CH2NR2 CH2S C C-H CC-CH2 CH2-C-
CH2F CH2Cl CH2Br CH2I CH2O CH2NO2
C-CH-C
RCOOH
RCHO
CC
C
C-CH2-C C-CH3
O
Ranges can be defined for different general types
of protons. This chart is general, the next slide
is more definite.
17
m
10 11 12 13 14
15
ALKENES
s
s
Monosubstituted
Disubstituted
cis-1,2-
s
trans-1,2-
s
1,1-
s
Trisubstituted
m
C-H OUT OF PLANE BENDING
Tetrasubstituted
1000
900
800
700
cm-1
18
m
10 11 12 13 14
15
BENZENES
Monosubstituted
s
s
Disubstituted
s
ortho
s
s
m
meta
para
s
RING Hs
Trisubstituted
OOPS
s
m
1,2,4
1,2,3
s
m
1,3,5
s
m
combination bands
1000
900
800
700
cm-1