C127 11 November 2014 The Synthesis and Characterization of Aspirin Objective: In this experiment, aspirin was synthesized from acetic anhydride and salicylic acid made in order to characterize its properties and determine its purity. The purity of the aspirin was examined by its melting point, thin layer chromatography, and UV spectroscopy. Introduction: Aspirin and acetic acid is synthesized by the formation of acetic anhydride and salicylic acid (Salicylic Acid + Acetic Anhydride Acetyl Salicylic Acid + Acetic Acid1). During the synthesis, the catalyst donates an H+ that attaches onto the reaction, but is not consumed.2 When the acetic anhydride is added, the O-H bond of the salicylic acid and the C-O bond of the acetic anhydride breaks, …show more content…
The temperature was recorded when melting started and when it finished. When finished, the capillary tubes were removed and the apparatus was shut off. Thin Layer Chromatography: A glass jar was obtained and filled with 0.5 cm of the solvent consisting of hexane, ethanol, and ethylacetate. The lid was put on so it could become saturated with vapor. A TLC plate was obtained and a line was drawn in pencil 1 cm from the bottom. The line was divided into four hash marks (A, SA, P, C). Add 0.2 g of the aspirin, salicylic acid, pure salicylic acid, and crude were put into labeled test tubes. 1 mL of methanol was added to the test tubes and was then stirred until the crystals dissolved. The solutions were drawn up using capillary tubes and dotted on the four hash marks on the TLC paper. Each of the dots were spotted twice rather small. The TLC paper was then put into the glass jar containing the solvent. The lid was put on until the solvent traveled within 2 cm of the top of the plate. It was then removed and the solvent was immediately marked before it dried. Once the plate dried, it was put under a UV lamp. The spots were marked with a …show more content…
mL Test Tube #2 3.14 x 10-4 M 5.0 mL 1.57 x 10-4 M 10. mL Test Tube #3 1.57 x 10-4 M 5.0 mL 7.85 x 10-5 M 10. mL The initial concentration of the salicylic acid and iron solution was given to be 4.00 x 10-3 M (M1). This concentration (M1) was multiplied by the volume (V1) of salicylic acid in the solution, and then divided by the volume of then entire solution of salicylic acid and iron (V2). This calculation gave us M2 for the initial solution and M1 for test tube #1. M2 for the initial solution calculated to be 1.57 x 10-3 M, 3.14 x 10-4 M for test tube #1, 1.57 x 10-4 M for test tube #2, and 7.85 x 10-5 M for test tube #3. Calculation 2: Determination of M2 M1V1=M2V2 Initial Solution: (4.00 x 10-3 M)(5.1 mL)=M2 (13 mL) M2= (4.00 x 10-3 M)(5.1 mL)/ (13 mL) M2 of Initial Solution = 1.57 x 10-3 M The same calculation technique was repeated for test tubes #1,2, and 3 Table 5: Absorbances of Salicylic Acid and Iron Solution Solutions: Absorbance Test Tube #1 0.31 Test Tube #2 0.14 Test Tube #3 0.11 Blank 0.00 Graph 1: Absorbance vs. Concentration to Determine Quantity of Salicylic