Acetylsalicylic Acid (Aspirin)
Alaina J. Pacquette, Jerlyn Williams
ABSTRACT: In this experiment, pure acetylsalicylic acid crystals are synthesized using salicylic acid, acetic anhydride and the catalyst, phosphoric acid. The reagents are warmed and melted in a reaction tube using a boiling bath. Once melted the synthesis of the product takes place. The product is then recrystallized by cooling, dried, and then weighed. The percentage yield of product for this experiment is 61.4%
METHOD
Used a digital scale, first taring it to weighing boat and placed about 0.1410g of salicylic acid crystals. Poured into a reaction tube. Simultaneously heated water bath until boiling. Added 3 drops of 85% phosphoric acid followed with 0.3 ml of acetic acid to the crystals. Agitated reactants then placed in a water bath for about 5 mins. Then added 0.2ml of distilled water to decompose excess acetic anhydride. When the reaction was completed added another 0.3ml of distilled water and allowed to cool down in an ice bath for about 10 minutes. The excess water was removed with a pipette; removed the crystals with a spatula then blotted with filter paper. The collected samples were placed in the oven for around 3 minutes to evaporate excess water then reweigh the crystals. Finally ground crystals in a mortar and pestle. Used a small sample then printed resulting graph from a mass spectrometer. *See mass spectrometer results attached
INTRODUCTION: Aspirin, also known as Acetylsalicylic acid, is one of the oldest and most versatile medical drugs. Aspirin is formed by bonding acetic acid to salicylic acid. The purpose of this is to counter the harsh effects salicylic acid has on the body while promoting the good effects of the acid on the body. To synthesize acid the two reagents are heated in the presence of an acid catalyst like phosphoric acid.The synthesis process is exothermic so the reaction tube should be handed with caution. Once the reaction takes place, the pure Acetylsalicylic acid crystals are formed through the process of recrystallization. Water is removed from the crystal and then it is washed and collected.
DATA AND OBSERVATIONS
Table 1. Observations
Salicylic Acid used
0.1410 g
Acetylsalicylic Acid collected
0.1130 g
SALICYLIC ACID
ACETIC ANHYDRIDE
ACETYLSALICYLIC ACID ACETIC ACID
Crystal appearance was white and chunky *See Attached Diagram of IR Spectrum*
MATERIALS
Distilled Water 138g salicylic acid 85% phosphoric acid 0.3 ml Acetic acid
Table 2. Results
Moles of Salicylic Acid Used
0.001021 moles
Theoretical yield of Acetylsalicylic Acid
0.001021 moles
Actual yield of Acetylsalicylic Acid
0.0006272 moles
Percentage Yield
61.4%
Journal of Grambling Chemical Society
CALCULATIONS
CONCLUSION
Balanced Equation:
We started with 0.1410g of salicylic acid and synthesized 0.1130g of acetylsalicylic acid giving a percent yield of 61.4%. Due to the fact that some of the product was lost in transferal from the reaction tube to filter paper. This concludes that the experiment was successful. Although the percentage yield wasn't high, it was enough recovered to
C,HjOz+ C?HgOz - CgHgO4+ CH,COOHJ Molar Ratio: C,HgOz:CgHgO4 1:1 0.001021 moles Salicylic Aci