Orgo 1-EXPERIMENT 5 Extraction Lab - Chioma Uka Professor...

This preview shows page 1 - 3 out of 6 pages.

Chioma UkaMarch 20, 2016Professor BerbosavOrganic Chemistry I LabEXPERIMENT 5: EXTRACTION LABOverall Objectives:Correlation of structure, polarity, acid and base characteristic and separation efficiency, role of extraction in separation rather than purification of compounds. Develop skills to perform an extraction effectively, including the use of appropriate solvents, ability to prevent the formation of an emulsion layer, removing residual water from the organic layer and evaporating the organic solvent.Theory:Extraction is an effective technique to selectively dissolves one or more of a mixture of compounds into an appropriate solvent. Liquid-liquid extraction to separate naphthalene and benzoic acid dissolves the mixture in the first solvent and then adding a second immiscible solvent that will selectively dissolve one of the components of the mixture does this. Once the two components are immiscible they can be vigorously mixed and thus allow for the transfer of adissolved compound from one layer to another. The purpose is to separate a binary solid mixture by extraction-washing and recrystallization, into its pure components. Purity will be tested by thin layer chromatography and/or melting point determination.Materials:Benzoic acidStirring RodSeparatory funnel50 mL Graduated CylindersRing & Ring Stand50 mL BeakersBurette ClampLitmus PaperWatch Glass125 Erlenmeyer FlaskProcedure: Weigh at approximately 2.0 grams of a 50:50 mixture of benzoic acid and naphthalene into a 50 mL Erlenmeyer flask. (Be sure to record the exact amount in the lab notebook). Next, add 20 mL of tert-butyl methyl ether and swirl to dissolve. Save about 0.5 mL of this dissolved mixture for TLC analysis.Transfer the rest of the solution to a separatory funnel using a little ether to rinse the flask. Add 10 mL of a 1 M sodium hydroxide solution to the funnel. Stopper the funnel and carefully mix the contents.
Chioma UkaMarch 20, 2016Professor BerbosavOrganic Chemistry I LabVent the funnel and then shake the mixture thoroughly, venting often to prevent pressure build-up. Allow the layers to separate completely, remove the stopper from the funnel anddrain out the lower ether layer into a labeled 50 mL Erlenmeyer flask.Extract the ether layer twice more with 5 mL portions of fresh 1 M sodium hydroxide solution. Doing smaller extractions is preferred over one large extraction because a largerfraction of the compound being extracted will move into the aqueous phase over multiple extractions, and avoiding emulsification will prevent skewed results.

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture