Infrared spectroscopy correlation table

Further information: 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