Typical solvents used in extraction ◦ ether ethyl

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Unformatted text preview: Typical solvents used in extraction ◦ Ether, Ethyl Acetate, Dichloromethane ◦ Are these solvents top layer or bottom? Techniques ◦ Mixing Cap, invert, swirl ◦ Venting Allow pressure to be released ◦ Separating Bottom layer goes out bottom Top out top Question: Let’s say you dissolve 1 gram of freebased cocaine (K = 4.0) in 15 mL water. How many grams will be in your aqueous layer after an extraction with 15 mL ether? What if you did the extraction 3 times? ◦ What if you just used 45 mL of ether in one big extraction? Why isn’t this better? No solvent we use is really 100% immiscible with water Must have techniques to remove traces left over from extraction ◦ First: Brine wash Saturated NaCl in water Organic fractions are “washed” with brine ◦ Second: Drying additive Anhydrous inorganic salt that likes to form hydrates Molecular seives Zeolite Anhydrous Inorganic Salts ◦ Na 2 SO 4 + H 2 O → Na 2 SO 4 • x H 2 O http://orgchem.colorado.edu/hndbksupport/drying/images/dabtls.html Used to purify compounds with small amounts of impurity Involves dissolving the crude solid in a hot solvent at high concentration ◦ More solute dissolves in hot solvents As the solvent cools, the compound begins to crystallize but impurities remain in the solution ◦ Impurities aren’t concentrated in the solvent Purer solid is collected by filtration ◦ Technique Choose a solvent that is sparingly soluble at room temperature but...
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Typical solvents used in extraction ◦ Ether Ethyl Acetate...

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