Aspirin, the most widely used drug in the world, has an interesting history. Since aspirin has a hydrophobic aromatic ring, it did not dissolve in water. If the melting point of the purified aspirin sample is lower than the expected or if it has a very broad range compared to the actual range, then the sample still contains some impurities. The reaction yield may be improved by adjusting the amount of reactant or product in the reaction. The synthesis of aspirin is classified as an reaction. Salicylic acid is a natural product that. Clamp the stoppered Erlenmeyer flask to a ring stand to hold it in the 70-80˚ C water bath.
The flask was heated for 5 minutes over a steam bath to hydrolyze excess acetic anhydride then rapidly cooled in an ice bath. Wash the beaker and the funnel with 5 to 10 mL of water. Crystallization, which uses the principle of solubility, was then used to remove most of the impurities and caused the acetylsalicylic acid to precipitate out of the solution. The purity of the synthesized aspirin was measured by determining its melting point and percent yield. There are many instruments that can be used to measure liquid amounts that differ in measuring capacity and accuracy, but the one used in this experiment is the graduated cylinder.
Next, the crude product was then purified by adding water which further lowered the solubility of acetylsalicylic acid and dissolved some impurities from the crystal of aspirin. The byproduct is acetic acid. Leave the filtered crystals undisturbed in the filter crucible for 10 minutes with the water aspirator on. The theoretical yield of crude aspirin product is 2. Next, place a few crystals of the crude product in a test tube labeled A and put to the side for later use.
In 1893, Felix Hofmann synthesized acetylsalicylic acid, which has all of the same medicinal benefits as salicylic acid but it did not have the side effect of irritating the digestive tract. This is why pyridine increases the rate of reaction more so than the acetate ion. After the mixture has heated for 10 minutes, remove it from the water bath and allow it to cool to room temperature. Several of years later the folk remedy of plants containing salicylate transformed into the cure-all medication known as aspirin. Once this is set up, turning on the apparatus will slowly heat up an aluminum block touching both the capillary tube and a thermometer. Heat the mixture for 5 minutes.
In this experiment aspirin, also known as acetylsalicylic acid, was synthesized from salicylic acid and acetic anhydride. This is partially because of the fact that Salicylic acid is a diprotic acid; this means that when Salicylic acid dissolves in water, it releases two Hydronium ions and makes the solution more acidic than if the same number of a monoprotic acid molecules were added. Much of this is believed to be due to decreased production of prostaglandins and thromboxanes. The present experiment will be the synthesis of a familiar organic compound called aspirin. During this semester, you will have an opportunity to isolate some pharmacologically active natural products and to synthesize other active compounds from suitable starting materials.
In the first part of the experiment, heating of the mixture was done and a clear yellow liquid was obtained Table 2. While waiting for the sample to vacuum dry weigh a weigh boat. To synthesize aspirin from salicylic acid and acetic anhydride. Add 10 mL of ethanol. Pour the contents in the 25 mL Erlenmeyer flask into a Buchner funnel attached to a vacuum filtration apparatus. Sulfuric acid serves as the acid catalyst since its conjugate base is a strong deprotonating group that is necessary in order for this reaction to be reversible.
Do not add the water until crystal formation is complete. A catalyst is something that changes the rate of a reaction, but is not actually consumed in the reaction itself. The phenol test was to test the purity of the aspirin product that was created during the experiment. The first factor that caused a low percent yield was caused because we lost some crude product when we were moving our crude product from the weigh boat to the 25 mL Erlenmeyer flask. When Acetic Anhydride is used as a reagent, the double bond on the ketone is transferred as a charge to the oxygen causing the opposite charges to attract. Calculate amount of acetic anhydride needed amount of salicylic acid times 3 2. The contents of each tube and 50 mL distilled water were then added to a 125 mL Erlenmeyer flask.
Then without delay since this solution if allowed to stand tends to become a semi-solid mass run in 7. A more stable structure is formed when the charge on the oxygen moves from being a lone pair to forming a double bond and the ether substituents are removed. If acetylsalicylic acid does not begin to crystallize out, scratch the walls of the flask with a glass rod. While all reactions will eventually take place, it is usually economically feasible if not practical to use an amount of a catalyst to speed up a reaction to an appreciable rate. The mechanism for this synthesis provides examples of three major classes of chemical reactions: hydrolysis, condensation, and proton transfer. Unknown compound C was the only unknown that underwent a color change when treated with iodine solution, meaning compound C was determined to be ground aspirin tablet even though there was some concentration of phenol present. Test this crude product for the presence of unreacted salicylic acid using the ferric chloride test.
Bring a 10 mL graduated cylinder to get acetic anhydride 4. The crucible is placed in the aspirator with a rubber stopper between the two pieces of equipment to ensure the seal between them. It is used to treat pain, reduce fever, and to decrease the aggregation of platelets, such as to decrease blood clotting. Taking this into account, the actual mass of the crude aspirin product is reduced to 2. Therefore when energy leaves one place it has to have another place to go to, it maintains a constant rate. Given a more dangerous setting, misreading or disregarding directions could result in injury, or worse.