IR Tables, UCSC
Table 1. Characteristic IR Absorption Peaks of Functional Groups
*
Vibration
Position (cm
-1
)
Intensity*
Notes
Alkanes
C-H stretch
2990 – 2850
m to s
Alkenes
=C-H stretch
3100 – 3000
m
C=C stretch
1680 – 1620 (sat.)
1650 – 1600 (conj.)
w to m
=C-H bend
995 – 685
s
See Table 2 for detail
Alkynes
≡C-H stretch
3310 – 3200
s
C≡C stretch
2250 – 2100
m to w
Aromatic Compounds
C-H stretch
3100 – 3000
m to w
C=C stretch
1625 – 1440
m to w
Hidden in fingerprint region
C-H bend
900 – 680
s
See Table 2 for detail
Alcohols**
O-H stretch
3550 – 3200
br, s
Hydrogen bonded (typical)
Amines
N-H stretch
3550 – 3250
br, m
Primary (two bands)
Secondary (one band)
Nitriles
C≡N stretch
2280 – 2200
s
Aldehydes
C-H stretch
2900 – 2800 &
2800 – 2700
s
H-C=O Fermi doublet
C=O stretch
1740 – 1720 (sat.)
1715 – 1680 (conj.)
s
Ketones
C=O stretch
1750 – 1705 (sat.)
1700 – 1665 (conj.)
s
Esters**
C=O stretch
1765 – 1735 (sat.)
1730 – 1715 (conj.)
s
Carboxylic Acids**
O-H stretch
3200 – 2500
br, m to w
C=O stretch
1725 – 1700 (sat.)
1715 – 1680 (conj.)
s
Amides
N-H stretch
3500 – 3150
m
Primary (two bands)
Secondary (one band)
C=O stretch
1700 – 1630
s
IR Tables, UCSC
Table 1 cont’d
Vibration
Position (cm
-1
)
Intensity
Notes
Anhydrides**
C=O stretch
1850 – 1800 &
1790 – 1740
s
Acid Chlorides
C=O stretch
1815 – 1770
s
Nitro Compounds
NO
2
stretch
1570 – 1490 &
1390 – 1300
s
Thiols
†
R-S-H stretch
2550 – 2600
Alkyl & Aryl Halides
†
C-F stretch
1000 – 1400
Hidden in fingerprint region
C-Cl stretch
< 600 – 840
C-Br stretch
< 700
C-I stretch
< 600
* Abbreviations: s = strong; m = medium; w = weak; br = broad; sat. = saturated; conj. = conjugated
** Alcohols, Esters, Carboxylic Acids, and Anhydrides also absorb in the fingerprint region due to the C-O
stretch (1300 – 1000, s).
Table 2. Out-of-Plane C-H Bending Vibrations in Alkenes and Aromatics
Alkene Structure
Position (cm
-1
)
Phenyl Structure
Position (cm
-1
)
Mono-substituted
997 – 985
&
915 – 905
Mono-substituted
770 – 730
&
720 – 680
Disubstituted, trans
980 – 960
Disubstituted, ortho
770 – 735
Disubstituted, cis
730 – 665
Disubstituted, meta
810 – 750
&
725 – 680
Disubstituted, symm.
895 – 885
Disubstituted, para
860 – 800
Trisubstituted
840 – 790
*
Adapted from…Mohrig, J. R.; Hammond, C. N.; Schatz, P. F. “Infrared Spectroscopy” in Techniques in
Organic Chemistry. Freeman: New York, 2006.
†
Palleros, D. R. “Infrared Spectroscopy” in Experimental Organic Chemistry. Wiley: New York, 2000. p.
688.
R
H
H
H
R
R
H
R
H
R
R
R
H
H
R
RR
R
R
H
H
R
R
R
R
H
R
CHEM 108M, Nuclear Magnetic Resonance (NMR) UCSC, Binder
Figures from Mohrig’s Techniques in Organic Chemistry, 3
rd
Edition.
3
CHEM 108M, Nuclear Magnetic Resonance (NMR) UCSC, Binder
Figures from Mohrig’s Techniques in Organic Chemistry, 3
rd
Edition.
4
CHEM 108M, Nuclear Magnetic Resonance (NMR) UCSC, Binder
Figures from Mohrig’s Techniques in Organic Chemistry, 3
rd
Edition.
5
CHEM 108M, Nuclear Magnetic Resonance (NMR) UCSC, Binder
Figures from Mohrig’s Techniques in Organic Chemistry, 3
rd
Edition.
6
