1. Electromagnetic Spectrum

2. 5.7 X 10 5 9.5 X 10 3 1.7 X 10 3 4.8 X 10 2 9.5 X 10 -3 1.27210 -4 Electromagnetic Spectrum (Kcal/mol)

3. Pi and non-bonding electrons Electromagnetic Spectrum Proton Spin Molecular Rotation Molecular Vibration and rotation nucleus valence electrons

4. Pi and non-bonding electrons Electromagnetic Spectrum Proton Spin Molecular Rotation Molecular Vibration and rotation nucleus NMR MicrowaveInfraredUltraviolet - Visible Mass Spectrometry X-ray diffractometry valence electrons

5. Infrared Spectroscopy To here!From here… Functional Groups: √ OH × C=O × C=C √ C-O Infrared (IR) Spectroscopy gives information on the functional groups within molecules

7. Infrared Spectroscopy

8. Typical stretching vibrations of a methylene group 12a–8

9. Different kinds of bending vibrations for a methylene group

10. RockingWaggingTwisting Symmetrical stretching Antisymmetrical stretching Scissoring

11. Schematic diagram of a typical infrared spectrophotometer

12. Fourier Transform Spectrometer, Interferogram and Spectrum

13. Factors affecting IR Stretch Frequency Masses of atoms at ends of a bond Springs connecting small weights vibrate faster than springs with large weights. H-C > C-C H-O > C-O Type of bond (force constant) Shorter, stronger springs vibrate faster than long, weak springs C ≡ C > C=C > C-C Hookes’ Law m2m2 m1m1

15. Fig. 10.15, p. 383 A Good Guide Low EnergyHigh Energy

16. Infrared spectra of 1-hexyne & 1-hexene

17. Infrared spectra of 1-hexene & 1-hexanol

18. Infrared spectra of butanal and 2-butanone

19. A Closer Look at Carbonyl Compounds