IR Frequencies Flashcards
(42 cards)
1
Q
Stiffer bonds vibrate…
A
faster
2
Q
Heaver atoms vibrate…
A
slower
3
Q
Hydrogen bonding groups have…
A
broad absorptions
4
Q
C-C
A
1200
5
Q
C=C, general
A
1660
6
Q
C=C, isolated
A
1640-1680
7
Q
C=C, conjugated
A
1620-1640
8
Q
C=C, aromatic
A
1600
9
Q
C(trip)C, terminal
A
2100-2200
sharp; moderate or weak
10
Q
C(trip)C, internal
A
very weak or absent
11
Q
C-H, sp3
A
2800-3000
12
Q
C-H, sp2
A
3000-3100
13
Q
C-H, sp
A
3300
sharp
14
Q
Alcohol O-H
A
3300
broad
15
Q
Amine N-H
A
3300
broad with spikes
16
Q
Primary amine/amide N-H
A
3300
broad with 2 spikes
17
Q
Secondary amine/amide N-H
A
3300
broad with 1 spike
18
Q
C-O
A
1000-1200
unreliable if present
indicative if absent
could be only clue for ethers
19
Q
Ketone C=O
A
1710
intense
20
Q
Aldehyde C=O
A
1725
intense
21
Q
Aldehyde C-H
A
2700 and 2800
22
Q
Acid C=O
A
1710
intense
23
Q
Acid O-H
A
2500-3500
broad; overlaps C-H region
24
Q
Ketone
A
C=O at 1710
25
Aldehyde
C=O at 1725
| Carbonyl C-H at 2700 and 2800
26
Acid
C=O at 1710
| O-H at 2500-3500, broad
27
Conjugated C=O
1685
C=C might not be evident
look for =C-H at 3000-3100
28
Amide C=O
1640-1680
| strong and broad
29
Primary amide C=O
1640
| strong and broad
30
Small carboxylic ester C=O
1735
characteristic!
lowered by conjugation
31
C-N
1200
| rarely useful
32
C=N
1660
| intense
33
C(trip)N
2200-2300
| strong
34
N-H, O-H, C-H region
2700-3500
35
C(trip)C and N(trip)N region
2100-2300
36
C=C, C=O, C=N region
1600-1850
37
C-C, C-O, C-N region
fingerprint region: 600-1400
38
Aromatic compound
C=C @ 1600
| =C-H > 3000
39
Acid chloride C=O
1800
40
Acid anhydride C=O
1750 and 1800
41
Ring strain...
raises frequency
42
Conjugation...
lowers frequency
