Infrared spectroscopy correlation table
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In physical and analytical chemistry, infrared spectroscopy ("IR spectroscopy") is a technique used to identify chemical compounds based on how 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.
Phosphonates could be also be characterized by two middle-sized bands between 2300 and 2400 cm−1.
| Bond | Type of bond | Specific type of bond | Absorption peak cm-1 (nm) | Appearance |
|---|---|---|---|---|
| C─H | alkyl | methyl | 1260 cm−1 (7937 nm) | strong |
| 1380 cm−1 (7246 nm) | weak | |||
| 2870 cm−1 (3484 nm) | medium to strong | |||
| 2960 cm−1 (3378 nm) | medium to strong | |||
| methylene | 1470 cm−1 (6803 nm) | strong | ||
| 2850 cm−1 (3509 nm) | medium to strong | |||
| 2925 cm−1 (3419 nm) | medium to strong | |||
| methine | 2890 cm−1 (3460 nm) | weak | ||
| vinyl | C═CH2 | 900 cm−1 (11111 nm) | strong | |
| 2975 cm−1 (3361 nm) | medium | |||
| 3080 cm−1 (3247 nm) | medium | |||
| C═CH | 3020 cm−1 (3311 nm) | medium | ||
| monosubstituted alkenes | 900 cm−1 (11111 nm) | strong | ||
| 990 cm−1 (10101 nm) | strong | |||
| cis-disubstituted alkenes | 670–700 cm−1 (14286-14925 nm) | strong | ||
| trans-disubstituted alkenes | 965 cm−1 (10363 nm) | strong | ||
| trisubstituted alkenes | 800–840 cm−1 (11905-12500 nm) | strong to medium | ||
| aromatic | benzene/sub. benzene | 3070 cm−1 (3257 nm) | weak | |
| monosubstituted benzene | 700–750 cm−1 (13333-14286 nm) | strong | ||
| 690–710 cm−1 (14085-14493 nm) | strong | |||
| ortho-disub. benzene | 750 cm−1 (13333 nm) | strong | ||
| meta-disub. benzene | 750–800 cm−1 (12500-13333 nm) | strong | ||
| 860–900 cm−1 (11111-11628 nm) | strong | |||
| para-disub. benzene | 800–860 cm−1 (11628-12500 nm) | strong | ||
| alkynes | any | 3300 cm−1 (3030 nm) | medium | |
| aldehydes | any | 2720 cm−1 (3676 nm) | medium | |
| 2820 cm−1 (3546 nm) | ||||
| C─C | acyclic C─C | monosub. alkenes | 1645 cm−1 (6079 nm) | medium |
| 1,1-disub. alkenes | 1655 cm−1 (6042 nm) | medium | ||
| cis-1,2-disub. alkenes | 1660 cm−1 (6024 nm) | medium | ||
| trans-1,2-disub. alkenes | 1675 cm−1 (5970 nm) | medium | ||
| trisub., tetrasub. alkenes | 1670 cm−1 (5988 nm) | weak | ||
| conjugated C─C | dienes | 1600 cm−1 (6250 nm) | strong | |
| 1650 cm−1 (6061 nm) | strong | |||
| with benzene ring | 1625 cm−1 (6154 nm) | strong | ||
| with C═O | 1600 cm−1 (6250 nm) | strong | ||
| C═C (both sp2) | any | 1640–1680 cm−1 (5952-6098 nm) | medium | |
| aromatic C═C | any | 1450 cm−1 (6897 nm) | weak to strong (usually 3 or 4) | |
| 1500 cm−1 (6667 nm) | ||||
| 1580 cm−1 (6329 nm) | ||||
| 1600 cm−1 (6250 nm) | ||||
| C≡C | terminal alkynes | 2100–2140 cm−1 (4673-4762 nm) | weak | |
| disubst. alkynes | 2190–2260 cm−1 (4425-4566 nm) | very weak (often indisinguishable) | ||
| C═O | aldehyde/ketone | saturated aliph./cyclic 6-membered | 1720 cm−1 (5814 nm) | |
| α,β-unsaturated | 1685 cm−1 (5935 nm) | |||
| aromatic ketones | 1685 cm−1 (5935 nm) | |||
| cyclic 5-membered | 1750 cm−1 (5714 nm) | |||
| cyclic 4-membered | 1775 cm−1 (5634 nm) | |||
| aldehydes | 1725 cm−1 (5797 nm) | influence of conjugation (as with ketones) | ||
| carboxylic acids/derivates | saturated carboxylic acids | 1710 cm−1 (5848 nm) | ||
| unsat./aromatic carb. acids | 1680–1690 cm−1 (5917-5952 nm) | |||
| esters and lactones | 1735 cm−1 (5764 nm) | influenced by conjugation and ring size (as with ketones) | ||
| anhydrides | 1760 cm−1 (5682 nm) | |||
| 1820 cm−1 (5495 nm) | ||||
| acyl halides | 1800 cm−1 (5556 nm) | |||
| amides | 1650 cm−1 (6061 nm) | associated amides | ||
| carboxylates (salts) | 1550–1610 cm−1 (6211-6452 nm) | |||
| amino acid zwitterions | 1550–1610 cm−1 (6211-6452 nm) | |||
| O─H | alcohols, phenols | low concentration | 3610–3670 cm−1 (2725-2770 nm) | |
| high concentration | 3200–3400 cm−1 (2941-3125 nm) | broad | ||
| carboxylic acids | low concentration | 3500–3560 cm−1 (2809-2857 nm) | ||
| high concentration | 3000 cm−1 (3333 nm) | broad | ||
| N─H | primary amines | any | 3400–3500 cm−1 (2857-2941 nm) | strong |
| 1560–1640 cm−1 (6098-6410 nm) | strong | |||
| secondary amines | any | >3000 cm−1 (>3333 nm) | weak to medium | |
| ammonium ions | any | 2400–3200 cm−1 (3125-4167 nm) | multiple broad peaks | |
| C─O | alcohols | primary | 1040–1060 cm−1 (9434-9615 nm) | strong, broad |
| secondary | ~1100 cm−1 (~9091 nm) | strong | ||
| tertiary | 1150–1200 cm−1 (8333-8696 nm) | medium | ||
| phenols | any | 1200 cm−1 (8333 nm) | ||
| ethers | aliphatic | 1120 cm−1 (8929 nm) | ||
| aromatic | 1220–1260 cm−1 (7937-8197 nm) | |||
| carboxylic acids | any | 1250–1300 cm−1 (7692-8000 nm) | ||
| esters | any | 1100–1300 cm−1 (7692-9091 nm) | two bands (distinct from ketones, which do not possess a C─O bond) | |
| C─N | aliphatic amines | any | 1020–1220 cm−1 (8197-9804 nm) | often overlapped |
| C═N | any | 1615–1700 cm−1 (5882-6192 nm) | similar conjugation effects to C═O | |
| C≡N (nitriles) | unconjugated | 2250 cm−1 (4444 nm) | medium | |
| conjugated | 2230 cm−1 (4484 nm) | medium | ||
| R─N─C (isocyanides) | any | 2165–2110 cm−1 (4739-4619 nm) | ||
| R─N═C═S | any | 2140–1990 cm−1 (5025-4673 nm) | ||
| C─X | fluoroalkanes | ordinary | 1000–1100 cm−1 (9091-10000 nm) | |
| trifluromethyl | 1100–1200 cm−1 (8333-9091 nm) | two strong, broad bands | ||
| chloroalkanes | any | 540–760 cm−1 (13158-18519 nm) | weak to medium | |
| bromoalkanes | any | 500–600 cm−1 (16667-20000 nm) | medium to strong | |
| iodoalkanes | any | 500 cm−1 (20000 nm) | medium to strong | |
| N─O | nitro compounds | aliphatic | 1540 cm−1 (6494 nm) | stronger |
| 1380 cm−1 (7246 nm) | weaker | |||
| aromatic | 1520, 1350 cm−1 (7407-6579 nm) | lower if conjugated |
See also
External links
moniquedavis42@yahoo.com www.usm.edu/soar www.intheknow.com www.greendot.com
editing infrared spectroscopy correlation table (section)://wwwchem.csustan.edu/tutorials/infrared.htm