Ochem Lab 10

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Experiment #4 3-12-2013 Title: Thin-layer and Column Chromatography Objective: Chromatography is a technique used for separating mixtures. In this experiment, column chromatography was used to separate fluorene from an oxidation product, 9-fluorenone. The purity of the compounds was determined using thin-layer chromatography. A UV lamp was used to visualize the developed TLC and the retention factor measurement for each substance. Material Data Table CompoundName | Molecular Weight (g/mol) | Melting Point (oC) | Boiling Point (oC) | Fluorene | 166.22 | 116-117 | 295 | 9-Fluorenone | 180.19 | 83.5 | 342 | Procedure/Observation: 1.) Preparation of the Column: Vertically clamp a dry 25mL buret that has a Teflon stopcock, keep it closed. Push a small plug glass wool into the bottom of the buret. Add clean dry sand, about a 1-cm layer on top of the glass wool, and then add 25mL of petroleum ether to the buret. Place a funnel on the top of the buret and slowly add 5g of dry alumina. When all of the alumina has been added, rinse the inside of the buret with additional petroleum ether to flush down any alumina that may be stuck to the sides. Add another 1-cm layer of dry clean sand on top of the alumina. Drain the solvent from the column until the solvent is at a level just above the top of the sand. The column is now ready for the addition of the mixture to be separated. 2.) Separation of the Fluorene and 9-Fluorenone Mixture: Accurately weigh 0.1g of the 1:1 mixture of fluorene and 9-fluorenone mixture, place it in a small test tube, and dissolve it in 0.5mL of petroleum ether. Add a few drops of dichloromethane, just enough to effect solution. Transfer the solution to the top of the column with a Pasteur pipet. Open the stopcock and slowly drain the column until the liquid level is at the top of the layer of sand. Add another 1-2mL of

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