In this experiment, we produced 4. 21 g of acetylsalicylic acid. Our theoretical yield was calculated to be 5. 22 g. Therefore our % yield was determined to be 80. 6%. The experimental boiling point range of acetylsalicylic acid was found to be 130-132° C. The true melting point of acetylsalicylic acid is 135° C, therefore our percent error range of for the boiling point is found to be 2. 2 – 3. 7 %. Introduction: Aspirin or acetylsalicylic acid (ASA) is a salicylate drug often used as an analgesic to relieve minor aches and pains, antipyretic to reduce fever, and as an anti-inflammatory. It is also used as an anti-platelet agent.
It works by preventing the synthesis of prostaglandins by inhibiting both the cyclooxygenase–1 (COX–1), which mediates platelet aggregation, gastric protection, and induction of renal function and cyclooxygenase–2 (COX–2) isoenzymes, which mediates tissue inflammation. Aspirin is in a class of medications called salicylates. Common adverse effects include: gastrointestinal (GI) distress (including upset stomach, heartburn, nausea, vomiting). Less common severe adverse effects include: tinnitus, Reye syndrome, GI ulceration, allergic reactions (including hives, shortness of breath, swelling, and/or anaphylaxis.
) Aspirin should not be taken with other salicylates, non–steroidal anti–inflammatory drugs (NSAIDs) such as ibuprofen or naproxen sodium, or anticoagulants such as Coumadin (warfarin). Aspirin can be purchased both over–the–counter (OTC) and by prescription (Rx) from a physician. OTC preparations: Aspergum, Bayer Aspirin, Bufferin, Ecotrin, Empirin, Halfprin, St. Joseph Aspirin, and many generics. Rx preparation: ZORprin Aspirin is synthesized from the acetylation (using acetic anhydride or acetyl chloride) of salicylic acid. Salicylic acid is a natural product that can be derived from the bark of a willow tree.
Salicylic acid is not used as an analgesic due to the highly acidic nature as it is damaging to mucous membranes. This is why this chemical is used as a ketatolytic (peeling) agent in the treatment of acne, corns, and warts. The addition of the acetyl group to the phenolic oxygen makes the medication less irritating to the esophagus and gastric lining. The balanced equation for the synthesis of aspirin is: Acetylsalicylic acid C? H? O? + C? H? O? C? H? O? + C? H? O? (Salicylic acid) + (Acetic anhydride) (Aspirin) + (Acetic acid) Results and Discussion: In the first part of the experiment, 4.
00 g of salicylic acid was put into a 125 mL Erlenmeyer flask with 8 mL of acetic anhydride. We then added 10 drops of concentrated phosphoric acid and swirled gently. The flask was then placed into a warm water bath of around 70-80° C. After 20 minutes 5. 0 mL of deionized water was added to decompose any excess acetic anhydride. We then removed the solution and allowed it to cool for 5 minutes while we prepared an ice water bath. To promote crystallization, 50 mL of deionized water was added to the solution and then the flask was immersed in the ice bath.
We then ran the products through Buchner filtration system to collect the aspirin crystals that had formed. When completed we allowed the complex to dry for a week in our lab drawers. When we weighed the product after a week of drying, we found that 4. 21 g of aspirin had formed. After running some calculations we discovered that salicylic acid was the limiting reactant in our procedure. Using this information and the fact that . 0290 mol of salicylic acid was used, our theoretical yield was calculated at 5. 22 g. By dividing our actual yield by the theoretical yield and multiplying by 100, the percent yield was found to be 80.
6%. In the second part of the experiment, we were checking the purity of the aspirin that we synthesized. The actual boiling point of aspirin is 135° C. By using a melting point apparatus, we packed 2-3 mm of our product into a capillary tube and placed it into the machine. By raising the temperature about 1° C per minute and observing the tube through the looking glass, the melting point range was determined experimentally to be 130-132° C. When compared to the actual melting point our percent error was calculated at 2. 3–3. 7%. There are several reasons that the actual yield of the experiments is not 100%.
Some reactions might be reversible, so the reaction doesn’t go all the way to completion. Other reactions do not go to completion because they require higher amounts of energy or maybe even more time. Substances in the reaction might be lost during the procedure during filtration or transferring or may be hard to separate from other parts of the experiment. Miscalculations in measurement might also lead to the yield being less than 100%. A certain amount of error is usually expected in most experiments. Data Table: 1) Mass of salicylic acid (g): _______4. 00 g______ 2) Moles of salicylic acid (mol): ______.
0290 mol____ 3) Volume of acetic anhydride (mL): ________8 mL______ 4) Density of acetic anhydride (g/mL): ______1. 08 g/mL____ 5) Mass of acetic anhydride (g): _______8. 64 g______ 6) Moles of acetic anhydride (mol): ______. 0846 mol____ 7) Drops of phosphoric acid: ________10________ 8) Mass of filter paper & watch glass (g): ______30. 04 g______ 9) Mass of filter paper, watch glass, & aspirin (g): ______34. 25 g______ 10) Mass of aspirin (g): _______4. 21 g______ 11) Limiting reactant: ____Salicylic acid____ 12) Theoretical yield (g): _______5. 22 g______ 13) Percent Yield (%): _______80.
6 %______ 14) Melting point range (oC): _____130-132° C_____ 15) True melting point (oC): _______135° C ______ 16) Percent error range (%): ______2. 2 – 3. 7 %____ Conclusion: The purpose of this lab was to synthesize aspirin, determine the mass of the product that was produced and then check the purity by determining the boiling point range. Additionally, the theoretical yield was calculated and then compared to the actual yield. Finally from those values a percent yield was calculated. Experimentally our percent yield was 80. 6% and the boiling point % error range was 2. 2-3. 7%.
Since the % range error didn’t fall within the actual boiling point, our sample was determined not to be 100% pure, although it did come pretty close. Some impurities could have entered into the solution and thrown off our sample from outside sources. There might have been some contaminates already in the flasks we used or the chemicals we used might not have been pure themselves. Sometimes when you open a bottle of aspirin you can detect a faint smell of vinegar. Vinegar also contains acetic acid. In the presence of excessive moisture, aspirin breaks down to acetic acid and salicylic acid. A faint smell of vinegar is ok for aspirin.
But the stronger the smell, the more the aspirin has broken down, decreasing the potency of the product. Some sources of error for this experiment may include some impurities in our solutions that could have affected the final products. Some product may have also been lost in the filtration process or in the transferring of the product to the watch glass from the filter. Human error could also have led to inexact amounts of reactants being administered, throwing off the calculations slightly.
References: http://www. disabled-world. com/artman/publish/aspirin. shtml#ixzz1sP8LzKBT accessed 04/18/12.