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. 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.
Group frequencies Tables of vibrational transitions of stable and transient molecules are also available.
Bond Type of bond Specific type of bond Absorption peak (cm−1) AppearanceC─Halkylmethyl1260strong1380weak2870medium to strong2960medium to strongmethylene1470strong2850medium to strong2925medium to strongmethine2890weakvinylC═CH2900strong2975medium3080mediumC═CH3020mediummonosubstituted alkenes900strong990strongcis-disubstituted alkenes670–700strongtrans-disubstituted alkenes965strongtrisubstituted alkenes800–840strong to mediumaromaticbenzene/sub. benzene3070weakmonosubstituted benzene700–750strong690–710strongortho-disub. benzene750strongmeta-disub. benzene750–800strong860–900strongpara-disub. benzene800–860strongalkynesany3300mediumaldehydesany2720medium2820C═Cacyclic C═Cmonosub. alkenes1645medium1,1-disub. alkenes1655mediumcis-1,2-disub. alkenes1660mediumtrans-1,2-disub. alkenes1675mediumtrisub., tetrasub. alkenes1670weakconjugated C═Cdienes1600strong1650strongwith benzene ring1625strongwith C═O1600strongC═C (both sp2)any1640–1680mediumaromatic C═Cany1450weak to strong (usually 3 or 4)150015801600C≡Cterminal alkynes2100–2140weakdisubst. alkynes2190–2260very weak (often indistinguishable)C=Oaldehyde/ketonesaturated aliph./cyclic 6-membered1720α,β-unsaturated1685aromatic ketones1685cyclic 5-membered1750cyclic 4-membered1775aldehydes1725influenced by conjugation (as with ketones)carboxylic acids/derivatessaturated carboxylic acids1710unsat./aromatic carb. acids1680–1690esters and lactones1735influenced by conjugation and ring size (as with ketones)anhydrides17601820acyl halides1800amides1650associated amidescarboxylates (salts)1550–1610amino acid zwitterions1550–1610O─Halcohols, phenolslow concentration3610–3670high concentration3200–3400broadcarboxylic acidslow concentration3500–3560high concentration3000broadN─Hprimary aminesany3400–3500strong1560–1640strongsecondary aminesany>3000weak to mediumammonium ionsany2400–3200multiple broad peaksC─Oalcoholsprimary1040–1060strong, broadsecondary ~1100strongtertiary1150–1200mediumphenolsany1200ethersaliphatic1120aromatic1220–1260carboxylic acidsany1250–1300estersany1100–1300two bands (distinct from ketones, which do not possess a C─O bond)C─Naliphatic aminesany1020–1220often overlappedC═Nany1615–1700similar conjugation effects to C═OC≡N (nitriles)unconjugated2250mediumconjugated2230mediumR─N─C (isocyanides)any2165–2110R─N═C═S (isothiocyanates)any2140–1990C─Xfluoroalkanesordinary1000–1100trifluoromethyl1100–1200two strong, broad bandschloroalkanesany540–760weak to mediumbromoalkanesany500–600medium to strongiodoalkanesany500medium to strongN─Onitro compoundsaliphatic1540stronger1380weakeraromatic1520lower if conjugated1350P─COrganophosphorus compoundaromatic1440-1460mediumP─Ophosphorus oxidebonded1195-1250strongfree1250-1300strong
See also Applied spectroscopy Absorption spectroscopy
References