Today: IR Next time: (see our website!) Partition coefficient and partition calculations

1. Today: IR Next time: (see our website!) Partition coefficient and partition calculations Separations of mixtures

2. Infrared (IR) spectroscopy http://www.chem.ucla.edu/~webspectra/index.html • IR region = 4000 - 400 cm-1(cm-1 unit is the wave number scale and is given by 1/wavelength in cm) E= h n • IR spectroscopy deals with the interactions between a molecule and radiation from the IR region of the electromagnetic spectrum • IR radiation causes the excitation of the natural vibrations of covalent bonds within that molecule and includes stretching and bending modes (C 334 molecular modeling experiments!) • Excitation of the natural vibrations of a bond leads to absorption of light of typical frequencies. This is recorded as a minimum on the IR spectrum. • The frequencies are typical for the atoms and bond types involved and allow us to determine functional groups.

3. Fingerprint region butyl acetate

4. http://www.chem.ucla.edu/~webspectra/index.html

5. http://www.chem.ucla.edu/~webspectra/index.html

6. Aromatics

7. http://www.chem.ucla.edu/~webspectra/index.html

8. http://www.chem.ucla.edu/~webspectra/index.html

9. Alcohols OH non-hydrogen bonded Gas phase!

10. Phenol OH hydrogen bonded

12. Ketones

13. Carboxylic Acids

14. ? ? ? ? ? ? ? ? C6H12O2

15. Next time: Partition coefficient and partition calculations Separations of mixtures (Print out from our Website and bring to class)