Introduction Aspirin, Caffeine and Salicylamide were extracted from an over-the-counter pain reliever (BC Powder). These components were separated by manipulating their solubilities by adjusting the acidity and basicity of the solution. By doing this, the three components were forced into conjugate acid (or base) forms, causing selective solubility in either an aqueous or organic solvent. These layers were then separated by use of a separation funnel. Once separated, the components extracted were characterized by measuring the melting point and performing a TLC analysis.
Also, the recovered aspirin from the first part of the experiment was recrystallized and compared to that of the isolated aspirin. Reactions Formula MW equivalence MP (? C) Density (g/mL) C9H8O4 180. 16 1 135 — NaHCO3 84. 01 1 50 2. 20 C9H7NaO4 202. 14 1 — H2O 18. 02 1 0 1. 00 CO2 44. 01 1 -56. 56 0. 720 Formula MW equivalence MP (? C) Density (g/mL) C9H7NaO4 202. 14 1 — HCl 36. 46 1 114. 17 0. 00149 C9H8O4 180. 16 1 135 — Formula MW equivalence MP (? C) Density (g/mL) C10H14N4 190. 24 1 236. 3 1. 23 HCl 36. 46 1 159 0. 00149 C10H15ClN4 226. 71 1.
Formula MW equivalence MP (?C) Density (g/mL) C10H15ClN4 226. 71 1 — NaOH 40. 00 1 323 2. 13 C10H14N4 190. 24 1 236. 3 1. 23 NaCl 58. 44 1 800. 7 36 H2O 18. 02 1 0. 0 1. 00 Experimental procedure: Aspirin (1. 30 g , 0. 00722 mol), Caffeine (0. 00666 g, 0. 000350 mol) and Salicylamide (0. 390 g, 0. 00284 mol) were combined in a 100 mL beaker. To this beaker, ethyl acetate (20 mL) and saturated NaHCO3 (10 mL) were added. The organic and aqueous layers were allowed time to separate before the organic layer was removed and put aside. An additional portion of NaHCO3 solution (10 mL) was added and the separation was repeated.
The aqueous layer was put aside in a beaker labeled “NaHCO3 Extract. ” To the organic layer still in the separatory funnel, 3M HCl (10 mL) was added. The resultant aqueous layer was drained and additional 3M HCl (10 mL) was added. This second aqueous layer was then drained into a beaker labeled “HCl Extract. ” The remaining organic layer was drained into a beaker labeled “Organic Layer. ” To the beaker labeled “Organic Layer”, 2 scoops of magnesium sulfate were added. The contents of the beaker were then gravity filtered into a round bottom flask.
This flask was then attached to a rotary evaporator and the solid was removed and placed in a vial labeled “OE” (Organic Extract). To the beaker labeled “NaHCO3 Extract”, 6M HCl (2 mL) was added to bring the pH to 6. After this, additional 6M HCl (10mL) was added. The solution was then vacuum filtered and washed with cold water. The solid was transferred to a vial labeled “BE” (Basic Extract). To the beaker labeled “HCl Extract”, 6M NaOH (2 mL) was added to bring the pH to 8. After this, additional 6M NaOH (10mL) was added. To the beaker, ethyl acetate (10 mL) was added.
The aqueous and organic layers were separated. The organic layer was drained into an Erlenmeyer flask. This solution was then treated with 3 scoops of magnesium sulfate. The solution was then gravity filtered into a round bottom flask. This flask was then attached to a rotary evaporator. After evaporation, the solid was transferred to a vial labelled “AE” (Acidic Extract). Three test tubes were then set up with small amounts of standard compounds of acetylsalicyclic acid (labelled “A”), caffeine (labeled “C”) and salicylamide (labeled “S”) dissolved in 5 drops of acetone.
Three more tubes were set up with small amounts of the solids from the vials labeled “OL”, “AE” and “BE. ” Acetone (5 mL) and hexane (5 mL) were then combined to make the developing solvent. A half-circle of filter paper was set into a 100 mL beaker and the bottom was covered with the developing solvent. A TLC plate was then prepared with a spot for each of the six test tubes. The TLC plate was then placed in the beaker and the solvent was allowed to reach 1 cm from the top of the plate. With the aid of a UV-lamp, the spots were circled. After each of the solids were completely dry, each was placed into a MelTemp device.
The temperature at which each solid began to melt and completed melting was recorded. From the vial labeled “AE,” aspirin (0. 533 g) was placed into a 50 mL Erlenmeyer flask with a boiling stick. Toluene (20 mL) was brought to a boil on a hot plate. The boiling toluene (10 mL) was then added to the aspirin until the solid dissolved completely. After allowing the solution to reach room temperature, the solution was placed in an ice bath for 16 minutes. After the crystals had formed, they were collected by vacuum filtration and weighed.
A small amount of the crystals were no weighed due to a lack of toluene with which to rinse the 50 mL Erlenmeyer flask of the last of the crystals. Results: Percent Recovery of Components Compound Aspirin Caffeine Salicylamide Actual Mass (g) 0. 671 0. 052 0. 283 Expected Mass (g) 1. 300 0. 0666 0. 390 Percent Yeild (%) 52% 78% 73% Melting Point Data Table Compound Aspirin Caffeine Salicylamide Actual MP (? C) 93 – 98 260 – 262 96 – 102 Expected MP (? C) 135 236 140 Percent Error (%) ~30% ~12% ~30% Aspirin Recrysalization Data Table Actual Mass (g) 0. 41 Actual MP (?C) 123-125 Expected Mass (g) 0.
533 Expected MP (? C) 135 Percent Recovery 77% Percent Error 8% TLC Analysis Data Table Compound Std. Aspirin Std. Caffeine Rf values 0. 38 0. 65 Error —~ 0% 29% 5% Std. Salicylamide 0. 73 Organic Acidic Basic 0. 69 0. 46 0. 38 Discussion: The three compounds were recovered in decent percentages during the extraction procedure. Each compound was extracted by following a the procedure which converted one component at a time into a water soluble version of itself. The aspirin was first ionized by the addition of a basic compound, sodium bicarbonate, into solution.
This caused the aspirin to be locked into the aqueous layer and readily separated by means of a separatory funnel. Once separated, the aspirin was returned to its initial form by the addition of hydrochloric acid. To remove the sodium chloride salts and water, the solution was vacuum filtered. This process yielded a 52% recovery of the aspirin by mass. It is assumed that aspirin molecules remaining in the organic solvent layer was responsible for the missing mass. During the melting point analysis, the aspirin melted in the temperature range of 93 – 98 ? C.
This shows a 30% error from the literature value of 135 ? C. The TLC analysis also supports that this basic extract was aspirin, as the Rf values of the basic extract and the standard aspirin were identical (0. 38). The next component to be isolated was the caffeine. The organic layer set aside after the removal of aspirin was treated with hydrochloric acid, which put the ionized caffeine into the aqueous solvent and the third component, salicylamide into the organic solvent. Setting the organic layer aside, caffeine was returned to its original form by the addition of sodium hydroxide, a base, to the solution.
To remove the resultant ionic compound sodium chloride and the water, the caffeine was dissolved in ethyl acetate and the organic layer removed. The water was then removed by magnesium sulfate, which in turn was removed by gravity filtration. Finally, the evaporator removed the ethyl acetate solvent, leaving only the solid caffeine. The caffeine returned a better yield then that of aspirin at a value of 78% recovery by mass. However, the melting point of the caffeine was strange in that the experimental value (260 – 262 ? C) was above the literature value (236 ? C, Error of 12%).
It was expected that impurities in the caffeine would result in a lower melting temperature, but this, however, was not the case. The TLC analysis also suggests the presence of significant impurities in the extracted caffeine. The standard returned a Rf value of 0. 65, whereas the sample returned 0. 46 (29% Error). The final component, salicylamide, was the only molecule that did not need to be ionized in order to be extracted. This was due to the fact that the other two components had already been removed and the solution therefore did not need to be partitioned between organic and aqueous layers.
To remove any residual water from the solution, magnesium sulfate was used. After performing a gravity filtration to remove the magnesium sulfate, the rotary evaporator was used to remove the ethyl acetate, leaving only the salicylamide solid. Salicylamide exhibited a similar percent recovery to that of caffeine, at 73% by mass. The results of the TLC analysis also supports salicylamide as the organic extract, with a standard Rf value of 0. 73 and an experimental value of 0. 69 (5% Error). After the extraction and TLC analysis was completed, a recrystallization procedure was carried out to try to purify the sample of aspirin.
After being dissolved in boiling tolulene, the solution was brought to a low temperature in an ice bath. This reduction in thermal energy encourage growth of aspirin crystals and the process had a 77% mass recovery rate. Part of the loss of aspirin was known to be caused by leaving trace amounts of solid in the round flask. A lack of toluene in the laboratory was to blame for this. After subjecting the crystals to a melting point analysis, they were found to be more pure than the original extract, exhibiting a melting point range of 123 – 125? C (Literature: 135? C). This implies a 8% error, a reasonable improvement over the former 30% error.