4,Purification by Flash Column Chromatography
4.1,Competent Chemist Rating:,Looks Can Be Deceiving”
Techniques Checklist,
Analyzing mixtures by TLC?
Assembling a silica gel column?
Applying crude mixtures to a silica gel column?
Separating simple mixtures with a silica gel column?
Pre-lab Discussion and Required Reading,
Theory of column chromatography, Zubrick Ch,27
TLC - polarity/solvent systems,Zubrick Ch,28,LLP Ch,9.3.1
Setting up a silica gel column,Zubrick Ch,29,LLP Ch,11.6
Applying crude mixtures to the column
Running a flash column
Equipment,
Flash Chromatography Column
Air flow apparatus (stopper,T-valve,screw clamp,tubing)
100-mL Round-bottomed flask
Test tubes - 18x150 mm
Test tube rack
TLC plates and spotters
UV lamp
Large plastic funnels
Digital Lab Techniques Manual,
3,TLC,The Basics
10,Column Chromatography
Goal,
Purify a contaminated compound using silica gel flash column chromatography.
28
WARNING NOTICE,The experiments described in these materials are potentially hazardous and require a high level
ofsafety training,special facilities and equipment,and supervision by appropriate individuals,You bear the sole
responsibility,liability,and risk for the implementation of such safety procedures and measures,MIT shall have no
responsibility,liability,or risk for the content or implementation of any of the material presented,Legal Notices
Experiment Outline,
You will receive 2 mL of an ether/pentane solution containing 1.00 g of
benzylacetone contaminated with a small amount of guaiazulene,
Make a TLC sample,and analyze this mixture by TLC,using 10% ethyl
acetate/hexanes as the solvent system - see TLC Guide,
Record the R
f
values,
Prepare the column in the hood,using 10% ether/pentane and 50 g (about 5’’) of
silica gel - see Flash Column Chromatography Guide,
Elute the column with 10 mL of pentane.
Apply your sample to the column,being careful not to disturb the top layer of
sand,Rinse the sample flask three times with 1 mL pentane each,and use the rinses
to wash the sides of the column,
Run the column - See Flash Column Chromatography Guide,
Monitor the fractions by TLC - See TLC Guide,
Concentrate the set of fractions containing pure benzylacetone.
Weigh the purified compound and prepare a GC sample.
Obtain a TLC and a gas chromatogram of the purified compound.
CH
3
H
3
C
O
CH
3
CH
3
H
3
C
Benzylacetone Guaiazulene
Results,
To obtain your "CC Rating" in Purification by Flash Column Chromatography,
you must collect at least 0.95 g of benzylacetone,This sample must be at least 95% pure as
demonstrated using gas chromatography,Your sample must also be submitted to the TA
for possible weight and purity verification,
29
4.1,Competent Chemist Rating:,Looks Can Be Deceiving”
Techniques Checklist,
Analyzing mixtures by TLC?
Assembling a silica gel column?
Applying crude mixtures to a silica gel column?
Separating simple mixtures with a silica gel column?
Pre-lab Discussion and Required Reading,
Theory of column chromatography, Zubrick Ch,27
TLC - polarity/solvent systems,Zubrick Ch,28,LLP Ch,9.3.1
Setting up a silica gel column,Zubrick Ch,29,LLP Ch,11.6
Applying crude mixtures to the column
Running a flash column
Equipment,
Flash Chromatography Column
Air flow apparatus (stopper,T-valve,screw clamp,tubing)
100-mL Round-bottomed flask
Test tubes - 18x150 mm
Test tube rack
TLC plates and spotters
UV lamp
Large plastic funnels
Digital Lab Techniques Manual,
3,TLC,The Basics
10,Column Chromatography
Goal,
Purify a contaminated compound using silica gel flash column chromatography.
28
WARNING NOTICE,The experiments described in these materials are potentially hazardous and require a high level
ofsafety training,special facilities and equipment,and supervision by appropriate individuals,You bear the sole
responsibility,liability,and risk for the implementation of such safety procedures and measures,MIT shall have no
responsibility,liability,or risk for the content or implementation of any of the material presented,Legal Notices
Experiment Outline,
You will receive 2 mL of an ether/pentane solution containing 1.00 g of
benzylacetone contaminated with a small amount of guaiazulene,
Make a TLC sample,and analyze this mixture by TLC,using 10% ethyl
acetate/hexanes as the solvent system - see TLC Guide,
Record the R
f
values,
Prepare the column in the hood,using 10% ether/pentane and 50 g (about 5’’) of
silica gel - see Flash Column Chromatography Guide,
Elute the column with 10 mL of pentane.
Apply your sample to the column,being careful not to disturb the top layer of
sand,Rinse the sample flask three times with 1 mL pentane each,and use the rinses
to wash the sides of the column,
Run the column - See Flash Column Chromatography Guide,
Monitor the fractions by TLC - See TLC Guide,
Concentrate the set of fractions containing pure benzylacetone.
Weigh the purified compound and prepare a GC sample.
Obtain a TLC and a gas chromatogram of the purified compound.
CH
3
H
3
C
O
CH
3
CH
3
H
3
C
Benzylacetone Guaiazulene
Results,
To obtain your "CC Rating" in Purification by Flash Column Chromatography,
you must collect at least 0.95 g of benzylacetone,This sample must be at least 95% pure as
demonstrated using gas chromatography,Your sample must also be submitted to the TA
for possible weight and purity verification,
29
