Organic Chemistry I Lab-Chem. 322 A Greener Glaser II: Oxidative Coupling of Alkynes: 2,7-Dimethyl-3,5-octadiyn-2,7-diol er Glaser Il: Oxidative Coupling of Alkynes: 2,7-Dimethyl-3,5-octadiyn-27-diol ã¢q pa25 mL filtering flask with a magnetic stirring bar and arm and secured with a small rubber band: (Practice placing a 19/22 white rubber septum tne tlask, folding the top of the septun down and over the lip of the fask Add 0.1g concentrated NH OH. Place a 19/22 White rubber septum over the top of the fask, purge Clamp the flask 1-2 ãabo eastr plate and let the o a small balloon attached to the side 0.1g of CuC catlalyst to the flask Tollowed by 10 mt 95% ethanol 1.0 mL- of 2-methy-3butyn-2-ol, and 0.5mf ygen for1 minute, then fill the baltoon untit mosty inflated- (Your instructor wil you with this procedure. ur. A greenish-blue or blue color should begin to develop almost imme diately. If the batoon deflates substantially, refill it with more oxygen. Stir for 1 hour to mix the slurry well at and every few minutes swirl the flask . Open the reaction flask, cool if warm, and add 0.5 m L of concentrated hydrochloric acid to neutralize the NH OH and keep the copper compounds in solution. Th colo a few more drops of acid. Add 2.5 mL of saturated NaÄI solution to precipitate Pasteur pipette, until all n. The color will change from b in color ater mixing thoroughly, add or yellow, If the mi the diol and stir the sion that results Add MTBE (methyl t-butyl ether) in 2mL increments, mixing well using a organic solids dissolve (add up to 6 mL MTBE, but no more). [Note: If a te precipitate forms, add additional water to the mixture to dissolve it. All solids should be dissolved at this point. Fransfer the mixture to a centrifuge tube and separete the two layers by removing the bottom ayer using a Pasteur pipette: Add-about 3mL of saturated NaCl solution to the organic layer and mix well using the pipette. Allow the layers to separate and again remove the bottom layer. The organic layer-shoutd be clear and cotortess or light yellow (IF NOTwash again with another 3 ml of saturated aqueous NaCt and separate the layers).Transfer the organic layer to a dry 16x100-mm-test tube and dry the solution with anhydrous sodium sulfate (use approximately the amount you would need to cover a dime) for at least 10 min: The drying agent should remain granular in appearance. Using a Pasteur pipette, transfer the organic layer to a 10mt Erlenmeyer flask teaving the drying agent behind Add-Norit activated charcoat (use approximately the amount you would need to cover a dime and boil the with a small cotton plug and about 1 cm of Celite. Use compressed air and a dry condenser hose to speed the filtration if necessary mixture gently for 2 minutes Filter the cooled solution through a fiter pipet fitted Rapidly boil off all the solvent on a hot plate set to -80°C in the hood. When the boiling, remove it from the heat. You should have a solid residue at this point. At your bench remove the last traces of solvent by connecting the flask to a vacuum trap apparatus using the thermometer adapter and a short glass tube solution stops At your bench, recrystallize the product from a minimal amount of boiling toluene. You will need to use a heating mantle to generate sufficient heat to boil toluene. Cool the solution slowly to room temperature, then cool on ice. Isolate the product using the Hirsch funnel rinsing the product with a small amount (ca. 0.5-1.0 mL) of ice-cold toluene. Allow the product to air dry in a sample envelop in your drawer until next week, and then determine the mp and yield. Submit your product (label as Diyne' with your 1 initial last name, w, and mp) to your instructor The aqueous filtrate from the reaction mixture should be placed in the acidic aqueous waste. The filtrates from recrystallization of the diol should be placed in the or Clean up: ganic non-halogenated waste
