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6-ResolutionSaltPrepF06 - swirling in order to ensure good...

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Resolution of a Racemic Mixture H COOH OH H HO COOH CH 3 Ph H H 2 N (S)-1-Phenyleythlamine COO- H HO COOH HO H Ph CH 3 NH 2 H Ph CH 3 NH 3 + H COO- H HO COOH HO H CH 3 Ph H + H 3 N (R)-1-Phenylethylamine RACEMIC MIXTURE + (2R,3R) - Tartaric acid Methanol (S)-1-phenylethylammonium (2R,3R) tartrate salt (R)-phenylethylammonium (2R,3R) tartrate salt (more soluble in methanol) (less soluble in methanol) Formation of Diastereomeric Salts ***Complete this portion of the experiment at least one week in advance. *** 1) Dissolve 6.0g of (+)- l -tartaric acid in 85 mL of methanol in an Erlenmeyer flask by heating the mixture on a hot plate in the hood. Important safety concerns: methanol is flammable and toxic to the optic nerve, so be careful not to allow vapors out into the laboratory and do not put your head into the hood for observation of dissolution of the mixture. 2) Slowly add 5.0 mL of the racemic phenylethylamine to the warm solution with
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Unformatted text preview: swirling in order to ensure good mixing. The solution will become hot as the exothermic salt formation progresses. 3) The solution is seeded with 1-2 crystals of the (S)phenylethylammonium–(2R,3R) tartrate salt. These crystals are prismatic in shape and are easily identifiable from the other diastereomer, which has long, thin needle like crystals. 4) The solution should be corked (with a cork or a rubber septa – NOT a ground glass stopper ), wrapped with parafilm, labeled and allowed to sit until the following lab meeting in order to allow for slow crystallization of the desired product. It is extremely important that the flask is sealed tightly so that the methanol does not evaporate, causing BOTH diastereomers to precipitate....
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