4 Feb 2019

Functional Group Characteristic Infrared Frequencies | Spectroscopy Guides

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This lookup chart is designed to provide insight into unknown peaks in your IR spectrum. It contains many common functional groups along with their characteristic IR absorption frequencies (in wavenumbers). Please insert your unknown peak in wavenumbers.

Potential matches are then displayed along with the other expected peaks, an indication of peak intensities and when the peak is expected to be broad followed by the peak assignment.

No frequency found
Alkane Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1350-1380 cm-1 ; Strong ; δ(-(H)2C-H)
1400-1470 cm-1 ; Medium ; δ(-C-H)
2800-3000 cm-1 ; Strong ; ν(-C-H)
Alkene Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
650-1000 cm-1 ; Medium ; δ(=C-H)
1640-1680 cm-1 ; Strong ; ν(-C=C-)
3000-3100 cm-1 ; Medium ; ν(=C-H)
Alkyne Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
610-700 cm-1 ; Medium ; δ(≡C-H)
2100-2260 cm-1 ; Weak ; ν(-C≡C-)
3270-3330 cm-1 ; Medium ; ν(≡C-H)
Aromatic Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
680-860 cm-1 ; Strong ; δ(≡C-H)
1550-1700 cm-1 ; Medium ; ν(-C≡C-)
3330-3335 cm-1 ; Variable ; ν(≡C-H)
Alcohol Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1087-1205 cm-1 ; Strong ; δ(-(C)O-H)
3200-3550 cm-1 ; Strong, Broad ; ν(-(C)O-H)
Phenol Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
680-860 cm-1 ; Strong ; δ(C-H)
1310-1390 cm-1 ; Strong ; δ(-(C)O-H)
1550-1700 cm-1 ; Medium ; ν(-C=C-)
3200-3550 cm-1 ; Strong, Broad ; ν(-(C)O-H)
3330-3335 cm-1 ; Variable ; ν(=C-H)
Aldehyde/Ketone Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1680-1750 cm-1 ; Strong ; ν(-C=O)
Ester Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1163-1210 cm-1 ; Strong ; ν(-C-O-)
1735-1750 cm-1 ; Strong ; ν(-C=O)
Carboxylic Acid Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
910-950 cm-1 ; Medium ; δ(-(C)O-H)
1210-1320 cm-1 ; Medium ; ν(-C-OH)
1395-1440 cm-1 ; Medium ; δ(-(C)O-H)
1680-1760 cm-1 ; Strong ; ν(-C=O)
2500-3300 cm-1 ; Strong , Broad ; ν(-(C)O-H)
Carboxylic Acid Anhydride Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1040-1050 cm-1 ; Strong , Broad ; ν(-(O=)C-O-C(=O)-)
1750-1820 cm-1 ; Strong ; ν(-C=O)
Primary Amine Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
660-900 cm-1 ; Medium ; δ(-(C)-N-H)
1020-1200 cm-1 ; Medium ; ν(-C-N-)
1500-1650 cm-1 ; Medium ; δ(-(C)-N-H)
3200-3500 cm-1 ; Medium, Two Bands ; ν(-(C)-N-H)
Secondary Amine Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
660-900 cm-1 ; Medium ; δ(-(C)-N-H)
1020-1200 cm-1 ; Medium ; ν(-C-N-)
3310-3350 cm-1 ; Medium ; ν(-(C)-N-H)
Tertiary Amine Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1020-1200 cm-1 ; Medium ; ν(-C-N-)
Imine Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2220-2260 cm-1 ; Weak ; ν(-C=N-)
Nitrile Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1640-1690 cm-1 ; Medium ; ν(-C≡N)
Azide Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2120-2160 cm-1 ; Strong ; ν(-N=N=N)
Oxyamine Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1290-1370 cm-1 ; Strong ; ν(-N-O-)
1475-1550 cm-1 ; Strong ; ν(-N-O-)
Isocyanate Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2250-2275 cm-1 ; Strong, Broad ; ν(-N=C=O)
Carbodiimide Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2120-2145 cm-1 ; Strong ; ν(-N=C=N-)
Thiocyanate Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2140-2175 cm-1 ; Strong ; ν(-S-C≡N)
Isothiocyanate Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2140-2175 cm-1 ; Strong ; ν(-N=C=S)
Akyl Fluoride Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1000-1400 cm-1 ; Strong ; ν(-C-F)
Alkyl Chloride Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
550-850 cm-1 ; Strong ; ν(-C-Cl)
Alkyl Bromide Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
515-690 cm-1 ; Strong ; ν(-C-Br)
Alkyl Iodide Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
500-600 cm-1 ; Strong ; ν(-C-I)
Thiol Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
2550-2600 cm-1 ; Weak ; ν(-S-H)
630-790 cm-1 ; Medium ; ν(-C-S-)
Sulfoxide Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1030-1372 cm-1 ; Strong ; ν(-S=O)
Thioketone Expected Bands; Intensity/Width; Assignment [δ = bend/ ν=stretch]
1000-1250 cm-1 ; Weak ; ν(-C=S)

A downloadable Lab Wall Poster containing this information is also available below.

Window and Frequency Guide

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