Magnesium Turnings Grignard Reaction

Flame dry all glassware before proceeding. Obtain 20 mL of diethyl ether in a 50 mL Erlenmeyer flask to use for the experiment. Assemble a Claisen tube, rubber septum, drying tube (containing anhydrous CaCl2), 25 mL round bottom flask and spin vane as shown below. Place 150 mg of magnesium turnings and a spin vane into the round bottom flask. Add a small crystal of iodine and attach reattach the flask to the assembly. In a clean, DRY 5 mL conical vial, dissolve 1.04 g of bromobenzene in 4 mL of diethyl ether. Add 1 mL of this solution to the flask of magnesium using a syringe and warm the flask over a hotplate while stirring. Once the reaction begins to boil, add the remaining bromobenzene solution drop-wise over the span of 10 minutes. Continue to gently reflux the reaction for an additional 10 minutes after all of the bromobenzene has been added, then cool to room temperature.

In a 5 mL reaction vial, dissolve 1.09 g of benzophenone in 2 mL of diethyl ether. Using a syringe, add this benzophenone solution dropwise to the stirred Grignard reagent prepared in Part A. Stir the reaction for an additional 10 minutes after all of the benzophenone has been added. If the reaction stops stirring, break up the solids with a spatula. Quench the reaction by adding 6 mL of 6M HCl, dropwise at first. (CAUTION! 6M HCl is a strong acid and can cause serious burns. Handle with gloves!)

Pour the contents of the reaction flask into a separatory funnel, rinsing the reaction flask out with another 2 mL of diethyl ether. Drain off the lower aqueous layer and then wash the remaining organic layer with 20 mL of saturated NaHCO3. Drain the lower aqueous layer and pour the organic layer into a 25 mL Erlenmeyer flask. Dry the solution over anhydrous Na2SO4. Decant the dried solution into a small beaker and evaporate the diethyl ether by warming gently on a hotplate under a hood.

Organic Chemistry Lab CHEM 304 Add 3 mL of petroleum ether to the solid, and warm the mixture gently to dissolve any biphenyl byproduct (do not boil away all of the petroleum ether!). Stir the mixture well with a stir rod or spatula during the heating period. Allow the mixture to cool and collect the solid via vacuum filtration. Determine the weight of your product, and obtain a melting point and IR spectrum.