Extraction 02 05 2015 Supplement B and A are on the end of the syllabus not in the book Turn it in set it up Cheating talk Post lab can t be copied from the book even if cited Everything should be in your own words Rules of Solvent 1 Orignal solvent and extraction solvent must be immiscible i Will be impossible if not 2 Extraction solvent can t irreversibly react with compound 3 Extraction solvent should be as specific to the compound as possible 4 Extraction solvent should be easily removed Secret about liquid liquid extractions Compound isn t soluble in extraction solvent if it s perfectly happily dissolved in original solvent So compound has to be changed solubility wise o Heat not with liquids o Pressure can be dangerous o Ionic strength o pH we ll be using this Experiment 1 gram of unknown that is preweighed o 1 1 1 acid base neutral o One of each in the supplements o Object which one do I have Take the sample and dissolve it in 20 mL of ethyl acetate o This is the original solvent 3 ten mL extractions with HCl We re going to use a sapratory funnel Don t break this Mix it o Nice gentle shaking please Ethyl acetate has a relatively high vapor pressure o Pressure increases as we shake so we must vent it Upside down and open the stopper thing Repeat this process for 15 minutes o Drain off but not off off save it the first batch of HCl and then add the next batch Keep draining them off into each other Then do the same exact thing but with NaOH When done we should have 30 mL of HCl will have the base o 30 mL of NaOH with the acid o and 70 mL of EA with the Neutral How do we get rid of the solvents now o Must neutralize acid and base o Take the 30 mL of HCl and neutralize with about 40 mL NaOH The base will precipitate which we will filter out o Do same with 30 mL of NaOH but with HCl o don t get confused Label EVERYTHING THEY ARE BOTH CLEAR M1V1 M2V2 o It ll take 30 mL of the opposite to neutralize it Measure pH every 5 mL How do we get rid of the ethyl acetate o We have to dry it first Add sodium sulfate and then FILTER o Air dry in a beaker Go over to the hood and blow air on it air tube High vapor pressure equilibrium will take 15 minutes Now we have crudes of the unknowns We will recrystallize them next lab PRINT OUT FLOW CHART OF EXTRACTION on website don t throw anything away this experiment until the very end 1 Compound is insoluble in cold solvent 2 compound soluble when the solvent is hot 3 Impurities solubility is temperature independent Recrystallization Done in an Erlenmeyer flask The volume needs to be just enough o Start with a small amount add the solid o Slowly add a little bit of solvent until the solid dissolved o Filter while still hot to remove impurities and then cool down solvent so that compound precipitates out o If impurities soluble then cool down the solvent and filter out the compound Need to collect melting point and percent recovery good will be 60 before and after recrystallization o recovery mass 0 333 o Where did it all go You need an explanation 62 before 29 after If the melting point doesn t change and is good then you lost it during recrystallization 42 before 39 after most of the sample was lost during the extraction process Explain how you lost it during those processes Melting point range is 1 C anything broader than that indicates impurities present o 5 7 degrees means 5 6 8 impurities 02 05 2015 02 05 2015