Max Hallgren1-19-2012Organic Synthesis

Data Chart

Mass of Salicylic Acid 3.3159 gMass of dry recrystallized Aspirin 1.8848 gExperimental Melting Point of Aspirin 122 – 128 °CTheoretical Melting point of Aspirin 137 °CColor of FeCl3 with Salicylic Acid PurpleColor of FeCl3 with Aspirin YellowColor of FeCl3 with recrystallized Aspirin Light PurpleOdor of Methyl Salicylate WintergreenOdor of FeCl3 with Methyl Salicylate Purple

Result Chart

Moles of Salicylic Acid used .02629 mol

Theoretical Moles of Aspirin .02629 mol

Theoretical Moles of Aspirin 4.7371 g

Percent Yield of Aspirin 39.788%

Procedure

A: Approximately 3 grams of Salicylic acid was placed in a 125 flask, massed to 3.3159

grams. 6 mL of Acetic Anhydride and 5 drops of Sulfuric Acid were added. The flask

was placed in a beaker with water warmed to about 80-90 °C for about 20 minutes, and

allowed to return to room temperature. Approximately 40 mL of distilled water was

added to the flask, which was then cooled in an ice bath. The crystals were subsequently

filtered and washed, and pressed between filter paper. Several crystals of aspirin and

Salicylic Acid were added, and placed into a beaker with about 5 mL of water and a drop

of FeCl3. The color was noted to be Purple. 6 grams of Aspirin were then dissolved in

about 20 mL of Ethanol in a 125 mL Erlenmeyer flask. After the Aspirin was completely

dissolved, 50 mL of distilled water were added, and the solution was allowed to cool.

After the crystallization process is complete, the crystals were filtered by gravity,

washed, and allowed to air dry. The crystals were tested with 1% FeCl3 for Phenolic

impurities.

B: About 1 gram of Salicylic Acid and 5 mL were placed in a test tube. 3 drops of

Sulfuric Acid were added, and the test tube was placed in a beaker of 70 °C water for

about 15 minutes, and the odor was recorded as wintergreen. One drop of FeCl3 caused

the acid to then turn very light purple.

Calculations

Moles of C7H6O3

Moles of C9H8O4

Grams of C9H8O4

Percent Yield

Conclusions

1. Yes, the Aspirin contained a noticeable amount of unreacted Salicylic Acid before

recrystallization, apparent from the purple color caused by the addition of Ferric

Chloride to the solution. Our Aspirin was relatively impure because the initial

crystals were not entirely formed when they were filtered.

2. Recrystallization saw a large improvement in the purity of our Aspirin. This time,

the Ferric Chloride test resulted in a much lighter purple.

3. Our melting point was an average of (.5)(128°C +122°C) = 125°C, approximately

12°C less than the theoretical melting point (137°C). This is most likely due to a

failure to recognize exactly when the Aspirin was melting.

4. The percent yield was significantly smaller than 100% because some of the

original mass consisted of impurities, and because some of the Aspirin adhered to

containers at different times.

5. There was likely a large amount of unreacted Salicylic Acid left over, indicated

by the color change of the Methyl Salicylate.