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Lecture 5

CHEM 235 Lecture Notes - Lecture 5: Petroleum Ether, Silica Gel, Ethyl Acetate


Department
Chemistry
Course Code
CHEM 235
Professor
Dana Zendrowski
Lecture
5

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NOTES:
Thin layer chromatography
- An indispensable analytical and preparative tool in organic chemistry
- Usually employed for the rapid separation and quantitative analysis of small
amounts of material
- Extremely convenient method: fast, reproducible and uses only a small amount of
sample (1 - 100 µg)
- Cannot be used with volatile compounds
- Process: based on the relative degree of partition of compounds between the given
moving liquid phase and a given solid stationary phase
Purposes:
a) Determine the number of compounds in a mixture (indicated by number of spots on
the developed plate)
b) Establish if two compounds are identical (indicated by identical Rf values with at least
two different developing solvents)
c) Determine the appropriate solvent for column chromatographic separation
d) Monitor a column chromatographic separation
e) Check the effectiveness of separation by column, recrystallization or extraction
f) Monitor the process of a reaction
EQUIPMENT:
100 mL beaker 10 mL graduated cylinder
watchglass micropipets
spatula TLC plates
3 - small test tubes filter paper
CHEMICAL HAZARDS AND WASTE DISPOSAL
Acetic acid
-
PROCEDURE:
1. Prepare developing chamber by adding approximately 8 mL of the premixed 1:1
petroleum ether: ethyl acetate solution
2. Add 3-4 drops of acetic acid to the chamber
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