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organic chemistry Activity: Column Chromatography Fe diacetylferrocene acetylferrocene ferrocene (dark red) orange) (yellow) The compounds in this experiment are convenient because they are colored and can be observed on the column easily. Ferrocene and its derivatives (above) are called sandwich compounds discovery and structural confirmation won the nobel prize in 1973 for wilkinson and Fischer All waste in this lab MUST BE PLACED IN A SPECIAL FERROCENE wASTE CONTAINER (fume hood) Procedure: 1. Obtain 020 g of ferrocene mixture and place in a small beaker. Add a spatula tip the (about 12 mg) of alumina powder to your small beaker with ferrocenes. Add just enough hexane/ethyl acetate (column solvent #2) to dissolve the ferrocenes and then stir the solution to dryness with a spatula. the following 2. Build your column according to the instructions on page 1. Also, obtain solvents in separate containers: 5 mL hexane, 10 mL of 7o/30 (hexane/ethyl acetate), and 5 mL of 95/5 (CH2Clz/CH3OH) 3. Begin the separation by using hexane as your mobile phase. You will see a yellow band running down the column. When this band begins to elute (or drain), collect it in a clean vial. Make sure you only collect this band it must be kept pure. If your bands are overlapping, they should be placed in a waste beaker. Throughout this experiment, IT IS MPORTANTTO CONTINUALLY ADD SOLVENT so THE coLUMN DOES NOT DRY OUT 4. When all of the yellow band has eluted, change your solvent system to a 70/30 mixture of a acetate. The orange band should begin to move faster. Collect this band in clean vial. Be careful to only collect this band, and not the darker red band 5. After the orange band has eluted, change your solvent system to 95/5 methylene chloride/methanol. Collect the last red band in a vial the hot 6. Prepare your fraction vials for TLC analysis by evaporating some of the solvent using plate in the hood. This will concentrate your fer for visual analysis, 7. Assess the purity of your fractions using TLC. spot each fraction on the plate with your starting mixture already spotted. Run this plate using 70/30 hexane/ethyl acetate as a TLC solvent. Circle the spots, and have your instructor grade the plate in lab! Re-draw the plate below, calculating the Rfvalues.Column Chromatography

8. After your has been graded, you can combine all of your vial solutions and pour TLC plate them into your waste beaker and add it to the large waste beaker in the hood. Please clean your vials with acetone and turn them back into the box on the front bench. uestions 1. What is the most polar compound, and based on its structure, why is that so? 2. Why do you begin with a nonpolar solvent and continually increase polarity instead of the other way around? 3. Are the factors controlling the movement of the compounds the same for TLC as they are for column chromatography? Briefly, why or why not? 4. The solvent for TLC works well at separating these 3 compounds. Rationalize why it was chosen, discussing polarity of solvent and the 3 ferrocenes.

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