Chem 333L Experiment 3 – A Chemical Extraction Theory Extraction is another method by which compounds can be isolated from each other. Unlike distillation, however extraction relies on the solubility of the compounds in various media rather than their boiling points. There are three types of extraction 1. Solid/liquid is the type of extraction used for coffee and tea. Only certain compounds in a solid are dissolved into the hot water while the rest remain behind. 2. Liquid/liquid extraction can be performed when there is a mixture of inorganic and organic liquids. An organic solvent such as ether will only dissolve the organic compound and separate into a distinct layer. This layer can then be removed and evaporated to leave only its organic solute. 3. Acid/Base reactions can be used on organic acids, bases, and neutral substances. Often it used to separate the product which can be removed by recrystallization or distillation. The ideal solvent: • Should share many of the properties of a recrystallization solvent. • Low boiling point • Should easily dissolve the substance to be extracted • Non-reactive with solute or solvents • Not toxic or flammable • Inexpensive if possible • Not miscible with water (at most 6.9g per 100mL of water) General points: 1. Strategy for acid/base extractions If multiple compounds are within the mixture, use ether as a solvent and mix with acids or bases that will only react with one compound. In this way it is possible to manipulate one compound at a time. 2. Emulsions An emulsion is the suspension of a liquid as droplets within another. This is something that must be prevented as it is a very stable state that will hinder the reaction. Shaking the solution as well as making it very ionic will help to prevent emulsions from forming. Adding an ionic compound such as NaCl will accomplish this. Some other methods to fight emulsions are vacuum filtration and centrifugation. 3. Pressure Build Up Pressure in an extraction mixture can occur with extremely volatile compounds that are exposed to the heat of acid/base reactions or merely the heat from one's hand. Precautions for this are frequent venting of the mixture via a separatory funnel. 4. Method for drying organic layer Organic solvents will dissolve some water when added to the mixture. After the organic layer is separated, the water needs to by removed efficiently with a drying agent that will not react with the solute or solvent. A common agent is Magnesium sulfate. Although fast and effective, it requires filtration to remove. Mechanism Procedure 1. Set up an ice bath. 2. Weigh and label 4 large test tubes (A,B,C,D). 3. Dissolve 1.00g of the ternary mixture in 6mL of ether and transfer to the separatory funnel.4. Add 2.0 mL of NaHCO3. Shake and swirl the solution in the funnel. Be sure to ventilate the solution frequently. 5. Remove bottom layer in the separatory funnel and put into TT-A. Place TT-A into ice bath. 6. Add 2.0 mL of NaOH to separatory funnel. Agitate the mixture as in the previous step and remove lower layer placing it into TT-B. Place TT-B into ice bath as well. 7. Add 1.4 mL of H2O into the separatory funnel. 8. Shake well and remove the lower H2O level. Discard this layer. 9. Place remnants into TT-C Test Tube A 1. Add 1.4 mL of ether and agitate. 2. Remove upper ehter layer and discard. 3. Add concentrated HCl dropwise until precipitate forms. 4. Cool TT-A in an ice bath to complete crystallization, suction filter, dry and obtain mass of benzoic acid. 5. Record melting point. 6. Calculate percent composition. Test Tube B 1. Add 1.4 mL of ether and agitate. 2. Remove upper ether layer and discard. 3. Add HCl dropwise until precipitate forms. 4. Cool, filter, dry, and record mass of 2-naphthol from TT-B. 5. Record the melting point and percent composition. 6. Calculate total percent recovery of the ternary mixture. Test Tube C 1. Add anhydrous MgSO4 (4-micro-scoops) 2. Decant liquid into TT-D and discard remnants. 3. Evaporate the ether completely from TT-D using steam bath. 4. Record mass of naphthalene from TT-D. 5. Record the melting point and calculate percent composition. ApparatusReagent Table Name, Structure, MW (g/mol) Melting C Boiling C Density g/mL Properties Diethyl Ether C4H10O 74.12 -116.3 34.6 0.71 Colorless liquid with sweet, ether odor Hydrochloric Acid HCl 36.46 -30 >100 1.2 Corrosive material Magnesium Sulfate MgSO4 120.36 1124 – 2.66 HYGROSCOPIC Drying agent White powder Sodium Hydroxide NaOH 39.99 318 1390 2.13 Corrosive Colorless, odorless solid HYGROSCOPIC Benzoic Acid C7H6O2 122.12 122.4 249 1.32 Flavoring preservative White Powder Naphthalene C10H8 81 218 1.14 Colorless to brown solid with an odor of mothballs 2-Naphthol C10H8 122 286 - White to brown powder LIGHT SENSITIVE Sodium Bicarbonate NaHCO3 84.00 50 1413 5.17 White crystals Disposal • Dispose of all organic solids in the organic waste container. • Dispose of ether in organic liquid waste container. • Dispose of gloves and paper towels in proper containers. Dispose of broken glass in broken glass container. ReferencesChemistry 333L&334L: Microscale Experiments in Organic Chemistry Organic Chemistry 10th