Aromatics

1. Aromatics Prominent (strong) features: C-H stretch 3100-3000 in-plane C-H bend 1300-1000 out of plane C-H bend 900-675 C=C ring stretches 1600-1585 and 1500-1400 out of plane C=C bend 450-400

2. combinationbands

3. IR of Alcohols O-H bend overlaps C-H bend 1209 C-O stretch 1023 O-H H-bonded 3331

4. IR of Alcohols cyclohexylcarbinol O-H non-hydrogen bonded or free OH 3650-3584 (sharp bands in gas phase) Intermolecular H-Bonding in solution increase with concentration gives bands at 3550-3200 (broader)

5. Ethers and Epoxides Ethers: C-O-C asymmetric stretch 1150-1085 (strong) C-O-C symmetric stretch is usually weak at 1075-1000 Epoxides: ring stretch near 1250and 950-810

6. Carbonyl Groups Ketones, aldehydes, carboxylic acids, carboxylic esters, lactones, acid halides, anhydrides, amides, lactams all show C=O stretch 1870-1540

7. IR of 2-Pentanone C-CO-C stretch 1171 C=O stretch 1717

8. Carbonyl Groups normal aliphatic ketones (acetone, cyclohexanone) 1715 replacement of alkyl group by heteroatom (G) shifts C=O stretch direction depends on inductive or resonance effect inductive: increases C=O freq. resonance: decreases

9. Effect of G G C=O Cl 1815-1785 F 1869 Br 1812 OH (monomer) 1760 OR 1750-1735 NH2 1695-1650 SR 1720-1690 Inductive Resonance

10. Aldehydes Aldehydes slightly higher freq. than methyl ketones C-H bend 760 C(O)-H stretch 2825, 2720 C=O stretch 1724

11. overtoneband combinationbands

12. Carboxylic Acids Broad OH absorption due to H-bonding 3300-2500 C=O stretch near 1760 ( aliphatic monomer) reduced to 1700 (aliphatic dimers) intramolecular H-bonding is usually stronger C=O stretch can be reduced to 1680

13. Acid Halide C-H stretch 3065 C=O stretch 1774 Fermi Resonance overtone of 872

14. Esters C=O stretch 1765 O-C=C asymmetric stretch 1193 C-H stretches

15. Amines N-H Stretch (as) 3372, (ss) 3290 N-H wag 900-700 N-H Bend 1617 C-N stretch 1073 octylamine Aliphatic C-H bands

16. Nitriles CºN stretch 2226 Aromatic C-H bands

17. IR of Benzylthiol S-H Bend 2565 Aromatic overtones Aliphatic C-H bands Aromatic C-H bands

18. IR of p-toluenesulfonate S=O stretch 1355, 1177 S-C-O stretch

19. Sample 1a

20. Solution Band at 2200 suggests CºC bands at 3300 suggest H-CºC bands around 3000 aliphatic C-H one possibility: C3H3Cl

21. Sample 1b

22. Solution High frequency bands suggest aromatic C-H and aliphatic C-H bands around 1600 suggest substituted aromatic one possibility: C10H14

23. Sample 1c

24. Solution High frequency bands suggest N-H, aromatic C-H and aliphatic C-H bands around 1600 suggest substituted aromatic one possibility: C7H9N

25. Sample 1d

26. Solution High frequency bands suggest O-H, aromatic C-H and aliphatic C-H bands around 1600 suggest substituted aromatic one possibility: C7H8O

27. Sample 1e

28. Solution High frequency bands suggest N-H, aromatic C-H and aliphatic C-H Note: N-H band is sharp… bands around 1600 suggest substituted aromatic one possibility: C8H11N

29. Sample 1f

30. Solution High frequency bands suggest aromatic C-H and aliphatic C-H bands around 1600 suggest substituted aromatic one possibility: C7H7Cl

31. Sample 1g

32. Solution High frequency bands suggest H-bonding and O-H and aliphatic C-H O2 suggest acid? But band at 1728 suggests strong C=O ….perhaps inductive effect of Cl one possibility: C3H5O2Cl

33. Sample 1h

34. Solution High frequency bands suggest H-bonding and O-H and aliphatic C-H O suggest alcohol? Note: no unsaturation one possibility: C5H12O

35. Sample 1i

36. Solution High frequency bands suggest aliphatic C-H band at 1718 suggests ketone band at 1650 suggest some unsaturation one possibility: C6H10O

37. Sample 1j

38. Solution High frequency bands suggest aromatic and aliphatic C-H bands at 1500-1400 suggest aromatic one possibility: C10H12

39. Sample 1k

40. Solution High frequency bands suggest aliphatic C-H bands at 2300 suggest CN second N; note no evidence of N-H one possibility: C5H10N2