Synthesis of Aspirin
Aspirin is the most commonly used drug in the United States. Forty million pounds are produced each year. The chemical name for aspirin is Acetylsalicylic acid. Aspirin is a pain reliever and a fever reducer. Aspirin originated from the bark of a White Willow Tree. Chewing the bark however is extremely acidicand irritates the mucous membranes of the mouth and stomach.Then, in 1893 a chemist named Felix Hoffman synthesized acetylsalicylic acid.
The purpose of this experiment is to synthesize aspirin from salicylic acid and acetic anhydride. To filter and air dry to find the actual yield for the synthesis procedure. And to prepare FTIR samplesand obtain infrared spectra of regeant grade salicylic acid and acetylsalicylic acid. Experimental Procedure
Firstly, the group weighed and recorded 2.0 grams of Salicylic acid into a 125 mL Erlenmeyer flask. Then we added 3 mL of Acetic anhydride and 2 drops of concentrated Sulfuric acid. Swirl the flask for proper mixing.
Then the group proceeded to warm the Erlenmeyer flask and the contents in a water bath to 95°C for 10 minutes. When the temperature was reached and kept for 10 minutes we took the flask away from heat and allowed it to cool to room temperature.
We then added 50 mL of cold DI water to the flask. Stirring well to allow the crystals to form. We then filtered the crystals using a vacuum filtration apparatus.
We then allowed the crystals to air dry on the filter paper with the vacuum aspirator still running for several minutes. Afterwards, we transferred the crystals to a watch glass and let sit overnight.
The next class period, Mr. Carey showed us what a FTIR card reader is. Mr. Carey explained what it does and how to use it. Each group then took turns to analyze their specimens and obtain an infrared spectrum on a graph on a computer.
Data and Observations
A good observation was that my group had an error in the mixing process of procedure A. We think we had an impurity in our flask, because our mix began to have a yellowish tint to it. And while we were heating our mix a greenish tint appeared. When we allowed to the mix to cool our crystals looked like snot. We then performed vacuum filtration on it and our crystals looked like pebbles you would find on the beach. Calculations and Graphs
Actual weight = 2.01 g
Theoretical weight = 2.61
Percent yield = (Actual weight/Theoretical weight) x 100
(2.01 g/2.61g) x 100 = 77.01 %
Questions and Answers
2. Esters are prepared by condensation (dehydration) of an alcohol with an acid.
3. A class of organic compounds in which a carbon (C) atom is bonded to an oxygen (O) atom by a double bond and to a hydroxyl group (−OH) by a single bond. A fourth bond links the carbon atom to a hydrogen (H) atom or to some other univalent combining group.
4. The reaction using acetic anhydride is faster and produces a higher yield.
Molar Mass of salicylic acid = 138 g
Molar Mass of acetylsalicylic acid = 180 g
180 g / 138 g = 1.3 g (Theoretical yield)
(1.02 g / 1.3 g) x 100 = 78.46% (Percent yield)
7. It is a test used to determine the presence or absence of phenols in a given sample. Conclusions
The main purpose of this lab is to obtain aspirin by chemical synthesis from salycylic acid by acetylation with acetic anhydride and crystallization. The purpose of crystallization is to create a pure sample. In this experiment, pure aspirin was obtained after filtering out the impurities and excess reagent through filter paper.
Some sources of error in this experiment could be the amount weighed, because the digital scale is very sensitive. Also, as my group discovered, impurities can sneak there way into the mix and cause for bad results. Works Cited...
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