Infrared spectroscopy correlation table

Short description: Table listing infrared absorption peaks for various bonds

Further information: Physics:Infrared spectroscopy

An infrared spectroscopy correlation table (or table of infrared absorption frequencies) is a list of absorption peaks and frequencies, typically reported in wavenumber, for common types of molecular bonds and functional groups.[1][2] In physical and analytical chemistry, infrared spectroscopy (IR spectroscopy) is a technique used to identify chemical compounds based on the way infrared radiation is absorbed by the compound.

The absorptions in this range do not apply only to bonds in organic molecules. IR spectroscopy is useful when it comes to analysis of inorganic compounds (such as metal complexes or fluoromanganates) as well.[3]

## Group frequencies

Tables of vibrational transitions of stable[4] and transient molecules[5] are also available.

Bond  | Type of bond  | Specific type of bond  | Absorption peak (cm−1)  | Appearance

|
|
|
|

C─H  | alkyl  | methyl  | 1260  | strong
1380  | weak
2870  | medium to strong
2960  | medium to strong
methylene | 1470  | strong
2850  | medium to strong
2925  | medium to strong
methine  | 2890  | weak
vinyl | C═CH2 | 900  | strong
2975  | medium
3080  | medium
C═CH  | 3020  | medium
monosubstituted alkenes | 900  | strong
990  | strong
cis-disubstituted alkenes  | 670–700  | strong
trans-disubstituted alkenes  | 965  | strong
trisubstituted alkenes  | 800–840  | strong to medium
aromatic  | benzene/sub. benzene  | 3070  | weak
monosubstituted benzene  | 700–750  | strong
690–710  | strong
ortho-disub. benzene  | 750  | strong
meta-disub. benzene  | 750–800  | strong
860–900  | strong
para-disub. benzene  | 800–860  | strong
alkynes  | any  | 3300  | medium
aldehydes  | any  | 2720  | medium
2820
C═C  | acyclic C═C  | monosub. alkenes  | 1645  | medium
1,1-disub. alkenes  | 1655  | medium
cis-1,2-disub. alkenes  | 1660  | medium
trans-1,2-disub. alkenes  | 1675  | medium
trisub., tetrasub. alkenes  | 1670  | weak
conjugated C═C  | dienes  | 1600  | strong
1650  | strong
with benzene ring  | 1625  | strong
with C═O  | 1600  | strong
C═C (both sp2)  | any  | 1640–1680  | medium
aromatic C═C  | any  | 1450  | weak to strong (usually 3 or 4)
1500
1580
1600
C≡C  | terminal alkynes  | 2100–2140  | weak
disubst. alkynes  | 2190–2260  | very weak (often indistinguishable)
C=O  | aldehyde/ketone  | saturated aliph./cyclic 6-membered  | 1720  |
α,β-unsaturated  | 1685  |
aromatic ketones  | 1685  |
cyclic 5-membered  | 1750  |
cyclic 4-membered  | 1775  |
aldehydes  | 1725  | influenced by conjugation (as with ketones)
carboxylic acids/derivates  | saturated carboxylic acids  | 1710  |
unsat./aromatic carb. acids  | 1680–1690  |
esters and lactones  | 1735  | influenced by conjugation and ring size (as with ketones)
anhydrides  | 1760  |
1820  |
acyl halides | 1800  |
amides | 1650  | associated amides
carboxylates (salts)  | 1550–1610  |
amino acid zwitterions  | 1550–1610  |
O─H  | alcohols, phenols | low concentration  | 3610–3670  |
high concentration  | 3200–3400  | broad
carboxylic acids  | low concentration  | 3500–3560  |
high concentration  | 3000  | broad
N─H  | primary amines | any  | 3400–3500  | strong
1560–1640  | strong
secondary amines  | any  | >3000  | weak to medium
ammonium ions  | any  | 2400–3200  | multiple broad peaks
C─O  | alcohols  | primary  | 1040–1060  | strong, broad
secondary  | ~1100  | strong
tertiary  | 1150–1200  | medium
phenols  | any  | 1200  |
ethers  | aliphatic  | 1120  |
aromatic  | 1220–1260  |
carboxylic acids  | any  | 1250–1300  |
esters  | any  | 1100–1300  | two bands (distinct from ketones, which do not possess a C─O bond)
C─N  | aliphatic amines  | any  | 1020–1220  | often overlapped
C═N  | any  | 1615–1700  | similar conjugation effects to C═O
C≡N (nitriles)  | unconjugated  | 2250  | medium
conjugated  | 2230  | medium
R─N─C (isocyanides)  | any  | 2165–2110  |
R─N═C═S (isothiocyanates)  | any  | 2140–1990  |
C─X | fluoroalkanes  | ordinary  | 1000–1100  |
trifluoromethyl  | 1100–1200  | two strong, broad bands
chloroalkanes  | any  | 540–760  | weak to medium
bromoalkanes  | any  | 500–600  | medium to strong
iodoalkanes  | any  | 500  | medium to strong
N─O  | nitro compounds | aliphatic  | 1540  | stronger
1380  | weaker
aromatic  | 1520  | lower if conjugated
1350
P─C  | Organophosphorus compound | aromatic  | 1440-1460  | medium
P─O  | phosphorus oxide  | bonded  | 1195-1250  | strong
free  | 1250-1300  | strong

## See also

* Applied spectroscopy
* Absorption spectroscopy

## References

1. ↑ George Socrates (12 April 2004). Infrared and Raman Characteristic Group Frequencies: Tables and Charts. John Wiley & Sons. pp. 18–. ISBN 978-0-470-09307-8. https://books.google.com/books?id=LDoAAjMnwEIC&pg=PP18. Retrieved 5 December 2012.
2. ↑ Peter Larkin (25 May 2011). Infrared and Raman Spectroscopy; Principles and Spectral Interpretation. Elsevier. ISBN 978-0-12-386984-5. https://books.google.com/books?id=KPyV1DRMRbwC. Retrieved 5 December 2012.
3. ↑ Kazuo Nakamoto (16 January 2009). Infrared and Raman Spectra of Inorganic and Coordination Compounds, Applications in Coordination, Organometallic, and Bioinorganic Chemistry. John Wiley & Sons. pp. 9–. ISBN 978-0-470-40587-1. https://books.google.com/books?id=IQZKdQ1rSKQC&pg=PR9. Retrieved 13 December 2012.
4. ↑ NSRDS-NBS: National Standard Reference Data Series, National Bureau of Standards. U.S. Government Printing Office. June 1972. https://nvlpubs.nist.gov/nistpubs/Legacy/NSRDS/nbsnsrds6.pdf. Retrieved 13 December 2012.
5. ↑ Jacox, Marilyn E. (2003). "Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules. Supplement B". Journal of Physical and Chemical Reference Data 32 (1): 1–441. doi:10.1063/1.1497629. ISSN 0047-2689. Bibcode: 2003JPCRD..32....1J.

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