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Unformatted text preview: Useful Spectroscopic Data Important Infrared Absorptions Type of Absorption Frequency, cm –1 , (Intensity) Comment Alkanes C–H stretch 2850–3000 (m) occurs in all compounds with aliphatic C–H bonds Alkenes C=C stretch –CH=CH 2 1640 (m) C CH 2 1655 (m) others 1660–1675 (w) not observed if alkene is symmetrical =C–H stretch 3000–3100 (m) =C–H bend –CH=CH 2 910–990 (s) C CH 2 890 (s) C C H H 960–980 (s) C C H H 675–730 (s) position is highly variable C C H 800–840 (s) Alcohols and Phenols O–H stretch 3200–3400 (s) C–O stretch 1050–1250 (s) also present in other compounds with C–O bonds: ethers, esters, etc. Alkynes C ≡ C stretch 2100–2200 (m) not present or weak in many internal alkynes ≡ C–H stretch 3300 (s) present only in terminal alkynes Aromatic Compounds C=C stretch 1500, 1600 (s) two absorptions C–H bend 650–750 (s) overtone 1660–2000 (w) Aldehydes C=O stretch ordinary 1720–1725 (s) α , β-unsaturated 1680–1690 (s) benzaldehydes...
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- Fall '10
- Carboxylic acid, stretch C=O stretch, Infrared Absorptions, stretch C=C stretch