1. Enterpretation of IR-spectra Tables and charts Assigning functional groups

2. Kort repetisjon/Short summery: -IR er meget godt egnet til identifisering av funksjonelle grupper. -IR is well suited for identification of functional groups - Funksjoneller grupper har karakteristiske absorbsjoner - Functional groups have characteristic absorptions - Absorbsjoner fra funksjonelle grupper er vanligvis relativt konstant - Absorption-frequencies from functional groups are relative constant -Symmetriske molekyler er inaktive for de frekvenser som tilsvarer symmetrisk strekk - Symmetrical molecules are inactive for symmeterical stretching frequencies

3. Alkanes C-H-stretch for CH 2 -groups in hydrocarbones occur in three areas: - Two bands at 2966 og 2853 (s) - Two band at 1375 og 1450 (m) - One band at 720 (not always) Branching has no significant influence. Ring strain increases C-H stretching frequency. Cyclo- propanes : 3100 – 2990.

5. Alkenes Non conjugated system : Mono substituted : C=C stretch at 1640 (m to w) Di(trans)-, tri- og tetra-substituted: C=C stretch at 1670 (weak if symmetry) Disubstituted cis (also cyclic): C=C ved 1650 Conjugated system: Often two C=C bands at 1650 og 1600 (of unsymmetric) Conjugation with aromat gives C=C strekk ved 1625 C-H stretch generally over 3000.

7. Alkynes C-H stretch for mono substituted 3333 – 3267 (s) Broad absorption at 700 – 610 Triple bond stretch at 2260 – 2100 (m to w) No or low absorption if symmetric molecule

9. Aromatics Aromatic C-H stretch at 3000 – 3100 (s) C-H bend at 900 – 675 (often strong and informative) C-C stretch at 1600 – 1585 and 1500 – 1400 (m) Overtones and combination tones at 2000 – 1650 (w)

11. Alcoholes og Phenoles Characterized by O-H og O-C stretch ”Free” O-H stretch at 3650 – 3584 (sharp) H-bondet O-H stretch at 3550 – 3200 (s, broad) C-O stretch at 1260 – 1000 (s)

14. Ethers and epoxides Alifatic C-O stretch ved 1115 – 1085 Aryl alkyl ethers at 1275 – 1200 and 1075 - 1020

16. C=O stretch Ketones, aldehydes, carboxylic acids, esters, lactones, acid halides, anhydrides, amides og laktames : All have C=O stretch in the area 1870 – 1540 which are relatively constant and easily recognizable. The frequency depends on: - Phase (solid, liquid or gas) - Elektronic and mass effects by neighbor substituent - Conjugation - Hydrogen bonding - Ring strain

17. Ketones Standard value for keton C=O stretch is 1715 (s) Conjugation gives delocalisation and reduction of C=O dobbel bond character. Weaker bond gives lower frequency. Conjugation with alken or aromat give C=O stretch at 1685 – 1666 Polar solvents reduce C=O stretch a little (5 – 15) Beta-diketones give keto-enol equil. and broad bands Ring strain increases C=O strekk (1775 for 4 ring) Electronegative alfa subs. increase frequency

20. Aldehydes Alifatic aldehyde C=O stretch at 1740 – 1720 (s) Electronegative substituents on alfa C increase frequency Conjugation give C=O stretch at 1710 – 1685 H-bonding reduce the C=O frequency C-H stretch at 2830 – 2695 A medium strong abs. at 2720 + C=O stretch give aldehyde

22. Carboxylic acids Dominenated by O-H stretch at 3300 – 2500 (H-bondet) Predominately dimers except at very low consentration C=O stretch for monomer vat 1760 (s) C=O stretch for dimer ved 1720 - 1706 Conjugation gives C=O stretch at 1710 - 1680 C=O stretch for carboxylate anion at 1650 – 1550 og 1400.

25. Esters and lactones Alifatic C=O stretch at 1750 – 1735 (s) Conjugation give C=O stretch ved 1730 – 1715 C-O stretch at 1300 – 1000 (s)

27. Carboxylic anhydrides Characterized by 2 C=O stretch at 1818 og 1750 (s) Conjugation give 2 C=O stretch ved 1775 og 1720 Ring strain increases the frequency C-O strekk ved 1047 (s)

29. Nitriles Alifatic C-N triple bond stretch at 2260 – 2240 (m) Conjugation give reduction to 2240 - 2222

31. Amines Primary amines give 2 bands at 3500 og 3400 (w) Secondary amines give 1 band at 3350 – 3310 H-bonding give lower frequency N-H bending at 1650 – 1580 (m)

33. Amides Amide C=O stretch at 1650 (s) N-H bending at 1655 – 1620 (m) N-H stretch ved 3520 – 3400 (2 bands for primary amide) Ring strain (lactames) increase C=O stretch frequency