Place 1.0 g of the chalcone and 7.5 mmol of ammonium formate per mmol of chalcon

ID: 947129 • Letter: P

Question

Place 1.0 g of the chalcone and 7.5 mmol of ammonium formate per mmol of chalcone in

a 100-mL round-bottomed flask. If you do not have 1.0 g of your chalcone, we may have

some in the stockroom, ask if you need some.

Prepare a water-cooled reflux condenser (See Figure 1 below, on page 4) before adding

any reagents to your round-bottom flask. Hook up the tubing and start the water flowing

(NOT TOO FAST!) at this time.

Weigh 0.10 g of 10% palladium on carbon on a weighing paper or plastic weigh boat and

add the Pd/C carefully to the flask so that it does not adhere to the ground-glass joint. Use

the powder funnel (the one with the wide bore) for this. If some of the black powder does

end up on the interior neck of the flask, wipe it off with a Kimwipe© and place the

Kimwipe© in the “Palladium Waste” bottle in the hood. Swirl the flask to coat the surface

of the black catalyst with the other reagents. (Safety precaution: Add the methanol only

after swirling the solid reagents together in the flask. Failure to do so can result in fire

and a burned hand!) Add 20 mL of methanol (by pouring it down the side of the roundbottom

flask) and again swirl the flask to mix the contents. The reaction mixture will start

bubbling even before it refluxes, due to the gas produced in the decomposition of

ammonium formate. (Reminder: Do not begin to time the reflux period until the methanol

is boiling and recondensing from the condenser). Attach the water-cooled reflux condenser

to the flask and place the flask in a sand bath. Begin heating the flask (turn the digital

setting on the hot plate/stirrer to 200 °C).

Heat the mixture at reflux for 15 minutes. Shorter heating can leave unreacted chalcone

and longer heating can produce complex product mixtures.

What is the theoretical yield of tetraphenylcyclopentadienone in grams?

The reaction is between chalcone and chalcone molecules, i.e it undergoes self condensation to give the desired product.

We are provided with 1 gram of chalcone

As mentioned that 7.5 mmol of ammonium formate per mmol of chalcone were taken

so moles of chalcone shold be 1 mmol

so therotical yieldshold be 1/2 mmol

molecular weight of Tetraphenylcyclopentadienone = 384'

so theoretical yield = 0.1 X 384 / 2 = 19.2 grams