TLC preparations:
Before starting the experiment, it is important to set up two TLC plates for testing purposes:
On one plate will be spotted samples from the beginning (pre-rxn) & ending (post-rxn) crude reaction mixtures. On another plate will be spotted samples from your three collected fractions.
Carry out the reaction (as specified in your text) in a medium sized test tube.
Before beginning to heat the reaction tube, spot your pre/post rxn TLC plate with the mixture, and set the plate aside to await spotting with the post rxn mixture.
Heat the reaction mixture in a 80oC water bath on a hot plate (multiple reaction tubes can be placed in one water bath. Be sure to make an identifying mark on your tube).
Make sure the reaction tube is only heated for 15 minutes.
After dissolving worked-up product in ether, and drying with calcium chloride, spot the ether solution on the TLC plate next to the spot of the pre-reaction mixture.
Evaporate (boil off) the ether in the hot water bath in order to collect the reaction product (make sure to place a boiling stick in the test tube!).
While the reaction tube is in the water bath, set up your column (as shown in your lab text).
To gauge the amount of adsorbant needed, fill the column halfway up with dry silica, and pour it into a small beaker.
Add 7-8 ml ligroin to the silica in the beaker, and swirl.
Add the adsorbant slurry to the column, tapping the column to release any pent-up air bubbles.
After addition of adsorbant slurry, open the stopcock, & allow the solvent to drain down to the approximate level of adsorbant, slowing the rate of flow as the solvent level nears the top of the adsorbant. Stop the flow when the depth of the solvent is ~5 mm above the adsorbant.
Add the fluorene/fluorenone mixture (dissolved in ~0.2 ml toluene) dropwise to the solvent layer at the top of the column. Open the stopcock just enough to allow the solvent level to slowly drop to the level of the adsorbant (DO NOT ALLOW THE SOLVENT LEVEL TO FALL BELOW THE ADSORBANT LAYER!).
Gently add enough sand through the top of the column to create ~3 mm layer on top of the adsorbant.
Carefully add 10 ml pure ligroin to the column. (Be careful not to upset the silica in the column upon addition of solvent).
Open the stopcock & collect this entire amount in an appropriately labelled flask (until the solvent level in the column approximately equals the level of the top of the sand).
Add 5 ml of 1:9 ether/ligroin mixture to the column, and collect this in another appropriately labelled flask.
Repeat this addition/collection step once more using 10 ml of 1:1 ether/ligroin mixture.
Testing of fractions:
Spot each fraction (next to each other) on a TLC plate. Develop this plate and the start/end reaction TLC plate using 4:1 hexane/methylene chloride solvent system.
Determine Rf values of all spots to compare in your report.