Infrared spectroscopy correlation table
Encyclopedia
In physical
and analytical chemistry
, infrared spectroscopy
("IR spectroscopy") is a technique used to identify chemical compound
s based on how infrared radiation
is absorbed by the compounds' chemical bond
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.
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