Lecture 4 - Extraction - Announcements • Next lab:...

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Unformatted text preview: Announcements • Next lab: Acid-Base Extraction • Before next lab period, complete: • Extraction Pre-Lab Quiz • TLC Post-lab quiz • Post-lab report for TLC • Pre-lab Notebook criteria: See website - Includes extraction __________*** ***You cannot begin without this! flow chart Extraction Extraction : Selective removal of one or more components of a mixture into a separate phase via partitioning . Partitioning : Selectively dissolving one component of a mixture into one of two immiscible solvents. Immiscible : Incapable of mixing; such mixtures form two layers or phases (i.e. oil and water) Extraction often employs acid-base chemistry!!! Immiscible solvents: Which is which? Neutral (uncharged) species in organic phase (bottom) Water CH 2 Cl 2 Salts (ionic species) in aqueous phase (top) Density of Water is 1.00 g/mL Density of CH 2 Cl 2 is 1.33 g/mL Which compounds are soluble in which phase? LIKE DISSOLVES LIKE! Extracting Agents Used in Liquid-Liquid Extraction Extracting Agent Substances Extracted Chemical Equilibrium Typical pK a Sodium Bicarbonate (NaHCO 3 ) pH 8 Sodium Carbonate (Na 2 CO 3 ) pH 10 Sodium Hydroxide (NaOH) pH 14 Hydrochloric Acid (HCl) pH 1 Sodium Bisulfite (NaHSO 3 ) Strong Carboxylic Acids Weak Carboxylic Acids Phenols Aliphatic Amines Aldehydes 2 - 5 4 - 6 9 - 11 9 - 11- Aromatic Amines R O OH + R O O NaHCO 3 Na + + H 2 O CO 2 R O OH Na 2 CO 3 R O O Na + NaHCO 3 + R OH NaOH + R O Na + H 2 O N R R'' R' HCl + N R R'' H R' Cl N R R' HCl + Cl R N R R' R H R O H NaHSO 3 + R H HO S O O O Na 4 - 5 Carboxylic acids (see above) Extractions Mixture of : benzoic acid, anthracene, and ethyl-4-amino benzoate Structures of Compounds OH O Benzoic Acid (Acid) Anthracene (Neutral) OEt O H 2 N Ethyl 4-amino benzoate (Base) Extracting Agents Used in Liquid-Liquid Extraction Extracting Agent Substances Extracted Chemical Equilibrium Typical pK a Sodium Bicarbonate...
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This note was uploaded on 09/14/2009 for the course CHEM 233 taught by Professor Miller during the Winter '08 term at University of Illinois at Urbana–Champaign.

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Lecture 4 - Extraction - Announcements • Next lab:...

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