The purpose of this lab was to learn how to use salicylic acid to make aspirin. Aspirin is the most widely used over-the-counter drug in the world. The average tablet contains about 325 milligrams of acetylsalicylic acid with an inert binding material such as starch. Aspirin is used to relieve pain, reduce inflammation, and lower fever. Aspirin originally was derived by boiling the bark of the white willow tree.
Although the salicin in willow bark has analgesic properties, purified salicylic acid was bitter and irritating when taken orally. Salicylic acid was neutralized with sodium to produce sodium salicylate, which was better-tasting but still irritated the stomach. Salicylic acid could be modified to produce phenylsalicylate, which was better tasting and less irritating, but released the toxic substance phenol when metabolized.
Felix Hoffman and Arthur Eichengrun first synthesized the active ingredient in aspirin, acetylsalicylic acid, in 1893 Experimental: -Placed 2. 06g of salicylic acid in Erlenmeyer flask -Added 5ml of acetic anhydride to Erlenmeyer flask via 10ml beaker -Added 5 drops of hydrochloric acid to Erlenmeyer flask via dropper -Dissolved the salicylic acid by swishing the solution around in a clockwise manner -The solution looked white in color, the solution was very watery -Set up a burner inside the hood to heat up the solution.
-Used clamps to hold solution over heated water until the solution was completely dissolved -As the solution was in the heated water bath the color changed from white to clear when the water temperature was at 75 degrees C -Set up Buchner funnel with side arm flask for filtration -Pulled the solution out of the heat bath after about 10 minutes, the temperature reached 82degrees C -Placed solution on a cork ring to cool -Solution remained clear.
-I put the solution in an ice bath and scratched the walls of the flask with a glass rod -Noticed that in the ice bath the solution turned from clear to a creamy white -After a few minutes in the ice bath the solution turned completely solid -Took solution out of ice bath, added 50ml of water to the solid solution and placed back in ice bath -Waited for crystals to form and grow the solution now looks like a snow globe with huge flakes of white particles floating in flask -After policing the solution we poured it in to the Buchner funnel -After filtration I recovered 4.
203g of product, noticed the crystals were very large in size -Took 25ml of sodium bicarbonate, added it with the product to a 150ml beaker -There was an instantaneous reaction that caused the solution to bubble, and make loud crackling noises -After stirring the solution white clumps remain, the solution appears as a gel type substance that was floating on the liquid sodium bicarbonate -Filtered the solution through a Buchner funnel once more.
-The solution in the side arm flask appeared to be clear but still had white particles floating around -Poured that solution into 10 ml of water and 3. 5 ml of hydrochloric acid mixture -Again there was an immediate reaction -Turned solid, white and kind of foamy -Turned the melting point apparatus on -Poured new foamy solution into Buchner funnel once again and washed the beaker with cold water -Pressed the liquid out of our aspirin with a cork -On the filter paper there was flattened out dry aspirin we recovered 2. 017g of product -Put some product on the melting point apparatus.
-The aspirin started to melt at 120degrees and was completely liquid at 121 degrees C -Performed a Ferric Chloride test -Took our product dissolved it in alcohol and added ferric chloride, and the test came back positive the solution did not turn blue it stayed the same amber-ish color meaning we made aspirin! Data: Salicylic acidAspirin 7 carbon2 carbon 3 oxygen 1 oxygen 6 hydrogen 2 hydrogen = 138g/ 1 mol = 42g/ 1mol Since salicylic acid is being reacted with acetic anhydride, salicylic acid is the limiting reactant of the reaction.
The balanced equation of the reaction of salicylic acid and acetic anhydride indicates that there is a 1:1:1:1 ratio between every reactant and product. Based on this, it can be concluded that the moles of salicylic acid, if reacted entirely, will yield an equivalent amount of moles of aspirin. To find the theoretical yield, you must know the molecular weight of aspirin and salicylic acid. First, the amount of moles of salicylic acid must be calculated by dividing the gram amount of salicylic acid, which is 2.
06 grams, and dividing it by its molecular weight, which is 138 grams per mole. 2. 06g/138g = 0. 0149 moles of salicylic acid This is the mole amount of salicylic acid as well as the theoretical mole amount of aspirin. To convert the mole amount of aspirin into grams, this number must be multiplied by the molecular weight of aspirin, which is 180g 0. 149mol * 180g = 2. 687g of aspirin Percent yield formula: Actual yield * 100 = 2. 017g/2. 687g = . 7506 *100 = 75. 06 percent recovered Theoretical yield.