Chemical Sciences: A Manual for CSIR-UGC National Eligibility Test for Lectureship and JRF/Infrared spectroscopy correlation table

In physical chemistry|physical and analytical chemistry, infrared spectroscopy ("IR spectroscopy") is a technique used to identify chemical compounds based on how infrared|infrared radiation is absorbed by the compounds' chemical bonds. 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. BondType of bondSpecific type of bondAbsorption peakAppearanceC─Halkylmethyl1260 cm−1strong1380 cm−1weak2870 cm−1medium to strong2960 cm−1medium to strongmethylene1470 cm−1strong2850 cm−1medium to strong2925 cm−1medium to strongmethine2890 cm−1weakvinylC═CH2900 cm−1strong2975 cm−1medium3080 cm−1mediumC═CH3020 cm−1mediummonosubstituted alkenes900 cm−1strong990 cm−1strongcis-disubstituted alkenes670–700 cm−1strongtrans-disubstituted alkenes965 cm−1strongtrisubstituted alkenes800–840 cm−1strong to mediumaromaticbenzene/sub. benzene3070 cm−1weakmonosubstituted benzene700–750 cm−1strong690–710 cm−1strongortho-disub. benzene750 cm−1strongmeta-disub. benzene750–800 cm−1strong860–900 cm−1strongpara-disub. benzene800–860 cm−1strongalkynesany3300 cm−1mediumaldehydesany2720 cm−1medium2820 cm−1C─Cacyclic C─Cmonosub. alkenes1645 cm−1medium1,1-disub. alkenes1655 cm−1mediumcis-1,2-disub. alkenes1660 cm−1mediumtrans-1,2-disub. alkenes1675 cm−1mediumtrisub., tetrasub. alkenes1670 cm−1weakconjugated system|conjugated C─Cdienes1600 cm−1strong1650 cm−1strongwith benzene ring1625 cm−1strongwith C═O1600 cm−1strongC═C (both sp2)any1640–1680 cm−1mediumaromatic C═Cany1450 cm−1weak to strong (usually 3 or 4)1500 cm−11580 cm−11600 cm−1C≡Cterminal alkynes2100–2140 cm−1weakdisubst. alkynes2190–2260 cm−1very weak (often indisinguishable)C═Oaldehyde/ketonesaturated aliph./cyclic 6-membered1720 cm−1α,β-unsaturated1685 cm−1aromatic ketones1685 cm−1cyclic 5-membered1750 cm−1cyclic 4-membered1775 cm−1aldehydes1725 cm−1influence of conjugation (as with ketones)carboxylic acids/derivatessaturated carboxylic acids1710 cm−1unsat./aromatic carb. acids1680–1690 cm−1esters and lactones1735 cm−1influenced by conjugation and ring size (as with ketones)anhydrides1760 cm−11820 cm−1acyl halides1800 cm−1amides1650 cm−1associated amidescarboxylates (salts)1550–1610 cm−1amino acid zwitterions1550–1610 cm−1O─Halcohols, phenolslow concentration3610–3670 cm−1high concentration3200–3400 cm−1broadcarboxylic acidslow concentration3500–3560 cm−1high concentration3000 cm−1broadN─Hprimary aminesany3400–3500 cm−1strong1560–1640 cm−1strongsecondary aminesany>3000 cm−1weak to mediumammonium ionsany2400–3200 cm−1multiple broad peaksC─Oalcoholsprimary1040–1060 cm−1strong, broadsecondary~1100 cm−1strongtertiary1150–1200 cm−1mediumphenolsany1200 cm−1ethersaliphatic1120 cm−1aromatic1220–1260 cm−1carboxylic acidsany1250–1300 cm−1estersany1100–1300 cm−1two bands (distinct from ketones, which do not possess a C─O bond)C─Naliphatic aminesany1020–1220 cm−1often overlappedC═Nany1615–1700 cm−1similar conjugation effects to C═OC≡N (nitriles)unconjugated2250 cm−1mediumconjugated2230 cm−1mediumR─N─C (isocyanides)any2165–2110 cm−1R─N═C═Sany2140–1990 cm−1C─Halide|Xfluoroalkanesordinary1000–1100 cm−1trifluromethyl1100–1200 cm−1two strong, broad bandschloroalkanesany540–760 cm−1weak to mediumbromoalkanesany500–600 cm−1medium to strongiodoalkanesany500 cm−1medium to strongN─Onitro compoundsaliphatic1540 cm−1stronger1380 cm−1weakeraromatic1520, 1350 cm−1lower if conjugated __NOTOC__ __NOEDITSECTION__