Question

Grignard theoretical yield... also, what is the limiting reactant?

Procedure: The Claisen adapter is fitted to the neck of a 100 mL round bottom flask containing 1-2 crystals of solid iodine and 0.5 g of magnesium metal (Mg). In the side arm of the adapter, place a reflux condenser with water hoses connected, but not flowing. Insert the vacuum connecting tube into the top of the condenser. Place the glass stopper into the other joint of the connecting tube and attach a DRY piece of rubber tubing connected to a drying tube. The drying tube should have two cotton plugs and sufficient DRIERITE (anhydrous CaSO4) between them to ensure that any air getting into the system is dried by the Drierite. Place the separatory funnel in the straight arm of the adapter. Open the stopcock so there is a flow path from the funnel to the flask. Insert a second vacuum connecting tube into the top of the separatory funnel. Place the glass stopper into the other joint of the connecting tube and attach a DRY piece of rubber tubing connected to a drying tube. The drying tube should have two cotton plugs and sufficient DRIERITE (anhydrous CaSO4) between them to ensure that any air getting into the system is dried by the Drierite. Once the apparatus is assembled, use a heating mantle on medium heat to heat the flask until sublimed iodine appears on the inside walls of the flask (rosy color). Close the separatory funnel. The apparatus should now be dry enough to allow formation of the Grignard reagent to occur. After the apparatus has cooled, start the water flowing gently through the condenser. To prepare the phenylmagnesium bromide, add 5 mL of anhydrous ether to the flask (through the separatory funnel) followed by 0.5 mL of bromobenzene. Close the stopcock on the separatory funnel. After a minute or so, bubbling should occur as the reaction begins and the reaction mixture should begin to turn slightly brown. If no reaction appears to begin, warm the flask gently with your hand. When the reaction begins, add 1.5 mL of bromobenzene in 15 mL of ether, and add this solution to the separatory funnel. Slowly add the bromobenzene solution from the separatory funnel dropwise at a rate of about two drops per second. This should be a rate sufficient to keep the reaction going without further heat. There should be sufficient heat from the reaction to maintain the ether at reflux. If the reaction appears to be going too fast and the ether vapors are high on the walls of the reflux condenser, use an ice bath to cool the reaction to the point that the ether vapors are no more than one-third of the height of the reflux condenser. When all of the bromobenzene has been added, heat the reaction at reflux for about 25 minutes with a low heat heating mantle. Prepare a solution of 2.25 g of benzophenone in 10 mL of anhydrous ether (in the closed separatory funnel