CHEM 222 – Review Session. February 9, 2009. Topics to be Covered. Theory behind: Separations IR NMR MS Practice Problems. Separations. Chromatography: a powerful separation method used to separate a mixture of compounds
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February 9, 2009
The components are separated accordingto the degree to which they are retained bythe stationary phase.
Areas of peaks are proportional to their concentration in the mixture.
Rf = distance travelled by compound
distance travelled by solvent front
(change in bond angle relativeto original bond axis)
(change in distance betweenatoms along bond axis)
-C C 2150 cm-1
-C N 2150 cm-1
-C=C- 1640 cm-1
-C=O 1720 cm-1
Double bond = 1
Ring = 1
Triple bond = 2
For a rotating positive charge
(reverse direction of μ for negative charge)
ΔE = hv
1. # of signals = # of types of protons
All protons do not absorb energy at the same frequency due to difference in electronic environments
2. Position of signals = chemical environment of protons
3. Intensity of signals = # of protonsIntegration of peaks gives relative amounts of each kind of proton.
The most intense (tallest) peak is the Base Peak.
Its fixed at 100%
Molecular Ion: last peak to the right
But molecular ion is not always present
If MW is even, most fragments will have odd mass
If MW is odd, most fragments will have even mass
ONLY compounds with an odd number of Nitrogenswill have an odd MW