Infrared and NMR Spectroscopic Data for Organic Compounds - Prof. John A. Colapret, Study notes of Chemistry

Download Infrared and NMR Spectroscopic Data for Organic Compounds - Prof. John A. Colapret and more Study notes Chemistry in PDF only on Docsity! CH 318N Dr. John A. Colapret 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=CH2 1640 (m) C CH2 1655 (m) others 1660–1675 (w) not observed if alkene is symmetrical =C–H stretch 3000–3100 (m) =C–H bend –CH=CH2 910–990 (s) C CH2 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 1700 (s) C–H stretch 2720 (m) Ketones C=O stretch ordinary 1710–1715 (s) increases with decreasing ring size α,β-unsaturated 1670–1680 (s) aryl ketones 1680–1690 (s) 2 Important Infrared Absorptions (continued…) Carboxylic Acids C=O stretch ordinary 1710 (s) benzoic acids 1680–1690 (s) O–H stretch 2400–3000 (s) very broad Esters and Lactones C=O stretch 1735 (s) increases with decreasing ring size Acid Chlorides C=O stretch 1800 (s) second weaker band sometimes observed at 1700–1750 Acid Anhydrides C=O stretch 1760, 1820 (s) two bands; increases with decreasing ring size in cyclic anhydrides Amides and Lactams C=O stretch 1650–1655 (s) increases with decreasing ring size N–H bend 1640 (s) N–H stretch 3200–3400 (m) doublet absorption observed for some primary amides Nitriles C≡N stretch 2200–2250 (m) Amines N–H stretch 3200–3375 (m) several absorptions sometimes observed, especially for primary amines Characteristic 1 H NMR Chemical Shifts Type of Hydrogen (R = alkyl, Ar = aryl) Chemical Shift (δ)* Type of Hydrogen (R = alkyl, Ar = aryl) Chemical Shift (δ)* (CH3)4Si 0 (by definition) O RCCH2R 2.2–2.6 RCH3 0.8–1.0 O RCOCH3 3.7–3.9 RCH2R 1.2–1.4 O RCOCH2R 4.1–4.7 R3CH 1.4–1.7 RCH2I 3.1–3.3 R2C=CRCHR2 1.6–2.6 RCH2Br 3.4–3.6 RC≡CH 2.0–3.0 RCH2Cl 3.6–3.8 ArCH3 2.2–2.5 RCH2F 4.4–4.5 ArCH2R 2.3–2.8 ArOH 4.5–4.7 ROH 0.5–6.0 R2C=CH2 4.6–5.0 RCH2OH 3.4–4.0 R2C=CHR 5.0–5.7 RCH2OR 3.3–4.0 ArH 6.5–8.5 R2NH 0.5–5.0 O RCH 9.5–10.1 RCCH3 O 2.1–2.3 O RCOH 10–13 *Values are relative to TMS. Other nearby functional groups may cause the signal to appear outside of these general ranges.