Question

Determine the yield limiting reagent and the theoretical yield for the following multistep synthesis from the reaction of ethyl acetoacetate. Draw the chemical complete chemical reaction and mechanism of Product B (4,4-diphenyl-3-buten-2-one) to Product C provided the procedure below.

Procedure

Step 3 [Product B to Product C]
   Place the product [B] (4,4-diphenyl-3-buten-2-one) from the previous step (3 g) in a 250 ml round bottomed flask, add acetone (40 ml) and 1 M HCl (6 ml). Reflux on a water bath for 15 minutes. Add water (50 mL), with swirling, then extract with ether (2 x 30 mL). If the interface between the layers is difficult to see, try “salting-out” by adding some sodium bicarbonate solution to the separating funnel. Wash the combined ether layers with saturated sodium bicarbonate (15 mL), then saturated sodium chloride solution (15 mL), and dry over anhydrous sodium sulfate (because of the presence of acetone, it takes more time than usual to dry the solution). Remove the drying agent, then evaporate the ether and recrystallise the product from “hexane fraction” or similar hydrocarbon solvent. Slow cooling should reward you with excellent crystals, and the actual crystallisation process is fascinating to watch and can be amazingly fast once it is initiated. You may wish to chase a second crop here also, but your primary goal should be the next two steps. Record the yield, m.p., IR and 1H and 13C NMR spectra of product [C]. Submit a representative sample of all crops you obtain for inspection.