Infrared spectroscopy correlation table
Encyclopedia
In physical
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...

 and analytical chemistry
Analytical chemistry
Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials. Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of...

, infrared spectroscopy
Infrared spectroscopy
Infrared spectroscopy is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic...

 ("IR spectroscopy") is a technique used to identify chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

s based on how infrared radiation
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 is absorbed by the compounds' chemical bond
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

s. This article is an IR spectroscopy correlation table that lists some general absorption peaks for common types of atomic bonds and functional groups. Note that this information is unreferenced, and may not be accurate.

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.

Phosphonates could be also characterized by two middle-sized bands between 2300 and 2400 cm-1.
Bond Type of bond Specific type of bond Absorption peak Appearance
C─H alkyl methyl 1260 cm−1 strong
1380 cm−1 weak
2870 cm−1 medium to strong
2960 cm−1 medium to strong
methylene
Methylene
Methylene is a chemical species in which a carbon atom is bonded to two hydrogen atoms. Three different possibilities present themselves:* the -CH2- substituent group: e.g., dichloromethane ....

1470 cm−1 strong
2850 cm−1 medium to strong
2925 cm−1 medium to strong
methine
Methine
In chemistry, methine is a trivalent functional group CH, derived formally from methane. The methine group consists of a carbon atom bound by two single bonds and one double bond, where one of the single bonds is to a hydrogen...

2890 cm−1 weak
vinyl
Vinyl
A vinyl compound is any organic compound that contains a vinyl group ,which are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group...

C═CH2 900 cm−1 strong
2975 cm−1 medium
3080 cm−1 medium
C═CH 3020 cm−1 medium
monosubstituted alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s
900 cm−1 strong
990 cm−1 strong
cis-disubstituted alkenes 670–700 cm−1 strong
trans-disubstituted alkenes 965 cm−1 strong
trisubstituted alkenes 800–840 cm−1 strong to medium
aromatic benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

/sub. benzene
3070 cm−1 weak
monosubstituted benzene 700–750 cm−1 strong
690–710 cm−1 strong
ortho-disub. benzene 750 cm−1 strong
meta-disub. benzene 750–800 cm−1 strong
860–900 cm−1 strong
para-disub. benzene 800–860 cm−1 strong
alkynes any 3300 cm−1 medium
aldehydes any 2720 cm−1 medium
2820 cm−1
C─C acyclic C─C monosub. alkenes 1645 cm−1 medium
1,1-disub. alkenes 1655 cm−1 medium
cis-1,2-disub. alkenes 1660 cm−1 medium
trans-1,2-disub. alkenes 1675 cm−1 medium
trisub., tetrasub. alkenes 1670 cm−1 weak
conjugated
Conjugated system
In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in compounds with alternating single and multiple bonds, which in general may lower the overall energy of the molecule and increase stability. Lone pairs, radicals or carbenium ions may be part of the...

 C─C
dienes 1600 cm−1 strong
1650 cm−1 strong
with benzene ring 1625 cm−1 strong
with C═O 1600 cm−1 strong
C═C (both sp2) any 1640–1680 cm−1 medium
aromatic C═C any 1450 cm−1 weak to strong (usually 3 or 4)
1500 cm−1
1580 cm−1
1600 cm−1
C≡C terminal alkynes 2100–2140 cm−1 weak
disubst. alkynes 2190–2260 cm−1 very weak (often indisinguishable)
C═O aldehyde/ketone saturated aliph./cyclic 6-membered 1720 cm−1
α,β-unsaturated 1685 cm−1
aromatic ketones 1685 cm−1
cyclic 5-membered 1750 cm−1
cyclic 4-membered 1775 cm−1
aldehydes 1725 cm−1 influence of conjugation (as with ketones)
carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

s/derivates
saturated carboxylic acids 1710 cm−1
unsat./aromatic carb. acids 1680–1690 cm−1
esters and lactones 1735 cm−1 influenced by conjugation and ring size (as with ketones)
anhydrides 1760 cm−1
1820 cm−1
acyl halide
Acyl halide
An acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group....

s
1800 cm−1
amide
Amide
In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

s
1650 cm−1 associated amides
carboxylates (salts) 1550–1610 cm−1
amino acid zwitterions 1550–1610 cm−1
O─H alcohols, phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

s
low concentration 3610–3670 cm−1
high concentration 3200–3400 cm−1 broad
carboxylic acids low concentration 3500–3560 cm−1
high concentration 3000 cm−1 broad
N─H primary amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s
any 3400–3500 cm−1 strong
1560–1640 cm−1 strong
secondary amines any >3000 cm−1 weak to medium
ammonium ions any 2400–3200 cm−1 multiple broad peaks
C─O alcohols primary 1040–1060 cm−1 strong, broad
secondary ~1100 cm−1 strong
tertiary 1150–1200 cm−1 medium
phenols any 1200 cm−1
ethers aliphatic 1120 cm−1
aromatic 1220–1260 cm−1
carboxylic acids any 1250–1300 cm−1
esters any 1100–1300 cm−1 two bands (distinct from ketones, which do not possess a C─O bond)
C─N aliphatic amines any 1020–1220 cm−1 often overlapped
C═N any 1615–1700 cm−1 similar conjugation effects to C═O
C≡N (nitriles) unconjugated 2250 cm−1 medium
conjugated 2230 cm−1 medium
R─N─C (isocyanide
Isocyanide
An isocyanide is an organic compound with the functional group -N≡C. It is the isomer of the related cyanide , hence the prefix iso....

s)
any 2165–2110 cm−1
R─N═C═S any 2140–1990 cm−1
C─X
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...

fluoroalkanes ordinary 1000–1100 cm−1
trifluromethyl 1100–1200 cm−1 two strong, broad bands
chloroalkanes any 540–760 cm−1 weak to medium
bromoalkanes any 500–600 cm−1 medium to strong
iodoalkanes any 500 cm−1 medium to strong
N─O nitro compounds aliphatic 1540 cm−1 stronger
1380 cm−1 weaker
aromatic 1520, 1350 cm−1 lower if conjugated

External links

  • http://wwwchem.csustan.edu/tutorials/quickir.htm
  • http://wwwchem.csustan.edu/tutorials/infrared.htm
  • http://orgchem.colorado.edu/hndbksupport/specttutor/irchart.html
  • http://www2.chemistry.msu.edu:80/faculty/reusch/VirtTxtJml/Spectrpy/InfraRed/infrared.htm
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