Answers the question, “How to ‘unmix’?” Separation Technologies Preparative Analytical Answers the question, “How to ‘unmix’?”

Separation Technologies Methods Precipitation Crystallization Distillation Extraction Chromotography LC GC Sieving Electrophoresis Magnetophoresis Diffusion Mass spectrometry Centrifugation

Two Broad Classifications Techniques based on Equilibrium Properties Separation Technologies Two Broad Classifications Techniques based on Equilibrium Properties Precipitation Crystallization Distillation Extraction

Separation Technologies Two Broad Classifications Techniques based on Differential Rates of Motion Chromatography Sieving Electrophoresis Magnetophoresis Diffusion Mass Spectrometry Centrifugation

Separation Technologies Extraction Two Types of extraction: Solid-Liquid Extraction Liquid-Liquid Extraction “Like dissolves like”

Separation Technologies Extraction Solid-Liquid Extraction 100 mL Separating Funnel Beaker

Separation Technologies Extraction Solid-Liquid Extraction 100 mL Separating Funnel Beaker

Separation Technologies Extraction Solid-Liquid Extraction 100 mL Solid Liquid

Separation Technologies Extraction Liquid-Liquid Extraction Organic Aqueous

Separation Technologies Extraction Two liquids that do not mix are said to be immiscible solvents Organic Aqueous

Separation Technologies Extraction What can be said about the relative density of these two products? The aqueous layer is more dense than the organic layer. Equilibrium constant Where [A]x is the concentration of the analyte in layer x Organic Note equilibrium constant also called partition or distribution coefficient. Aqueous

Extraction with a Separatory Funnel The basic set-up: A supported separatory funnel, with tap closed, the cool solution to be extracted (here the red aqueous solution) and the extracting solvent (here dichloromethane).

Extraction with a Separatory Funnel Pour in the solution using a funnel to ensure it goes into the separatory funnel. Do not pour too fast or the air inside the separatory funnel will not be able to escape quickly enough.

Extraction with a Separatory Funnel Pour in the extraction solvent with the same care as before. Note that the layers do not mix, and that because dichloromethane is more dense than water that it sinks to the bottom of the separatory funnel. What would happen if you were using diethyl ether?

Extraction with a Separatory Funnel After putting in the stopper, remove the separatory funnel from the stand. Try holding as shown with one hand at the tap and the other hand with the palm against the stopper to prevent it from coming out. With the tap pointed away from anybody, including yourself, and preferably into a fumehood, vent the system by opening the tap. This is to relieve any pressure build-up. Now close the tap again.

Extraction with a Separatory Funnel Without changing your hold on the separatory funnel, shake it briefly, then vent the pressure again. Repeat the process a couple of times.

Extraction with a Separatory Funnel Replace the separatory funnel into the stand and remove the stopper and allow the layers to separate. In the picture you can see the process starting... notice the two different colored areas towards the top and the bottom.

Extraction with a Separatory Funnel Once the layers have separated, run off the lower, more dense, dichloromethane layer into a flask, then run off the aqueous layer (shown) and you are done. An important lesson here is to keep ALL solutions from an extraction until you are sure you have the compound that you need. In many cases the extraction process will be repeated twice more, combining all the organic solutions at the end.

Extraction with a Separatory Funnel

Separation Technologies Extraction Example: I2 between CCl4 and H20 Calculate the number of millimoles of I2 remaining in 100 mL of an aqueous solution that was originally 1.00 x 10-3 M, after extracting with two 50 mL portions of CCl4 .

Separation Technologies Extraction Therefore, K can now be calculated

Separation Technologies Extraction

Separation Technologies Extraction

Separation Technologies Extraction Example: Now let’s compare with extraction of 100 mL of an aqueous solution that was originally 1.0 x 10-3 M, after extraction with 100 mL of CCl4 once:

Separation Technologies Extraction This is about 20 times worse!!!