Liquid-Liquid Extraxtion (pt.1) EXP 3 PDF

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Liquid-Liquid Extraction + Solubility Test Procedure: -

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Using a 125 mL EF, label it “Stock ether” and obtain diethyl ether from the fume hood. MAKE SURE THAT IT IS CORKED In a 50 mL beaker, weigh (g) the unknown mixture received Dissolve the solution in (Start with 25, you can go up to 40 if it doesn’t dissolve. If it doesn’t dissolve after 40, use NaOH (10-15)35-40mL of diethyl ether o Pour this into the separatory funnel o Using a dropper, rinse the side of the beaker out three times with approx. 2 mL of diethyl ether Shake the solution with 3 consecutive 10-15 mL portions of 10% NaOH o To avoid losing compound, add the NaOH to the beaker that contained the mixture, and then transfer that solution to the separatory funnel o NOTE: after each successive addition of NaOH, you will need to remove the aqueous layer from the bottom into a 100 mL beaker Once all three successive additions have been completed, wash the organic layer with 7.5mL of water, and collect this water in the 100 mL beaker o Label beaker as “ conjugate base of _______ “ There will be an organic layer still left in the separatory funnel. Pour this organic layer into a 50 mL EF and label it “ Neutral Fraction” o TO HELP WITH QUANTITATIVE TRANSFER: rinse the separatory funnel with approx. 3mL of diethyl ether, and add it to the 50 mL EF After removing the organic layer into the 50 mL EF, add anhydrous Na2SO4 for 5 minutes. FLASK IS CORKED FOR THIS ENTIRE PROCESS Once the organic layer has dried, pre-weigh a 50 mL round bottom flask (RBF), and gravity filter the solution into the RBF. o If there is too much to fit into the RBF, pour the remainder into an EF, CAP BOTH, then roto evap what you have, pour remaining solution that you filtered from EF into RBF, and Roto evap again o NOTE: you can rinse the EF flask with approx. 2mL of ether twice Using the roto-vap, remove the solvent. WEIGHT THE RECOVERY OF THE SOLUTION.

Neutralization of the aqueous solution and extraction of ACID Compound Using 400 mL beaker, create an ice water bath, and cool the beaker containing the conjugate base solution. To the beaker that is cooled, add 12M HCl 2 mL at time using a dropper o Do this until a precipitate forms and a red litmus test indicates that that the solution has turned acidic (5-10 mL approx. needed) WHEN COOLED: transfer this solution back to the separatory funnel. Successively extract this aqueous fraction using three 16 mL portions of diethyl ether

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o Add diethyl ether first into the 50 mL beaker, and then into the separatory funnel. In this case, since the ether extracting medium is the top layer, both the bottom and top layers must be removed from the funnel. The aqueous layer needs to be returned to the separatory funnel before adding the next portion of fresh ether. The ether layers will be collected into a 125 mL EF labelled “acid fraction”. After removing the last fraction of ether, rinse the empty separatory funnel with approx. 3 mL of ether and add this to the “acid fraction” flask, Dry the combined organic layers (the stuff in the EF) using anhydrous Na2SO4 Put the remaining aqueous portion in a beaker labelled as “waste”. Once the organic layer has dried, gravity filter the solution into a pre-weighted 100 mL RBF. Remove the solvent using rotary evaporator. Weigh what was recovered (g)...