Write a lab procedure to Isolate in pure form two of the three compounds... 50%

Question

Write a lab procedure to Isolate in pure form two of the three compounds...

50% 0-toluic acid, 40% fluorene, 10% 1,4-dibromobenzene

I already know how to separate the 50% o-toluic acid from the rest so I need to know how to separate the fluorene, 1,4-dibromobenzene from each other and purify them.

The following reagents will be available: 1M NaOH, 6M NaOH, 1M HCl, 6M HCl, 1M NaHCO3, saturated sodium chloride, diethyl ether, 95% ethanol, methanol, isopropyl alcohol, acetone, hexane, toluene, methylene chloride, and anhydrous sodium sulfate.

Please outline in detail how you would separate, isolate and purify the mixture above with the given reagents. ALL WORK MUST BE SHOWN!!

Explanation / Answer

Fluorene is a neutral hydrocarbon.
Toluic acid is an acid.
Dibromobenzene is a neutral compound.

If you dissolve all this in an appropriate reagent (hexane might do it, or ether), then throw into a sep funnel and increase the pH with NaOH, you will deprotonate the toluic acid making it negatively charged. It will move to the aqueous layer. Separate the water layer (with the toluic acid) from the organic phase, which will have the fluorene and dibromobenzene.

If you want to recover the toluic acid, then you can reacidify, back extract to organic phase, and dry with anh. sodium sulfate. Crystallize, collect.

I'm not sure from the question if you now have to seperate the fluorene from the dibromobenzene.The easiest way would be column chromatography (at least in my opinion). Fluorene is colored so it would be easy to elute and collect. If this doesn't sound good, you may be able to evaporate one of these off on a rotovap (check the boiling points). I'm not sure what lab equipment you have available, and I can't see an obvious way to do this by sep funnel extraction as they are both neutral. let me know what you think...

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