Today:
IR
Next time:
(see our website!)
Partition coefficient and partition calculations
Separations of mixtures
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.
Fingerprint region
butyl acetate
http://www.chem.ucla.edu/~webspectra/index.html
http://www.chem.ucla.edu/~webspectra/index.html
Aromatics
http://www.chem.ucla.edu/~webspectra/index.html
http://www.chem.ucla.edu/~webspectra/index.html
Alcohols
OH
non-hydrogen
bonded
Gas phase!
Phenol
OH
hydrogen bonded
Ketones
Carboxylic Acids
????????
C6H12O2
Next time:
Partition coefficient and partition calculations
Separations of mixtures
(Print out from our Website and bring to class)