C4H6O3 (Acetic anhydride) + H2O (Water) -------------------------> 2C2H4O2 (Acetic Acid)
The acetic acid and phosphoric acid are water soluble and it is removed by washing the aspirin with chilled water. Salicylic acid is only slightly soluble in water and is not completely removed in the washing steps. Phosphoric acid can be used instead of sulphuric acid if desired to obtain the higher yield, as sulphuric acid reacts more readily with the organic molecules involved in the reaction than phosphoric acid. However, phosphoric acid does not absorb water in the reaction; therefore it may be a slower process.
Final purification is completed by the process of Recrystallisation. By recrystalising the crude aspirin slowly, it was possible to obtain large crystals with an exact structure by allowing the aspirin molecules to join together in a precise way. The regular molecular crystal structure of the final product makes it more difficult for impurities to be included, eliminating impurities present in the formless crude product. The impure aspirin is dissolved in warm ethanol. The solution is then cooled slowly, and the aspirin crystallises out of solution leaving the salicylic acid and other impurities behind.
In my experiment, pure aspirin was obtained after filtering out the impurities and excess reagents through the filter paper. A method to check a solid compound’s purity after recrsytallisation is to check its melting point. The melting point of a compound can be used to identify it and also to estimate its purity. Normally an impure compound will show a melting point which is lower than that of a pure compound. Therefore, if the sample of aspirin melts at a temperature below the accepted melting point two possibilities can exist; either the sample is impure or it is not aspirin. A pure substance will melt sharply at 1-20C per minute when nearing the expected melting point in order to get a more accurate range. An impure compound will melt over a wider temperature range.
You May Also Find These Documents Helpful
-
Isolation of Aspirin: The organic filtrate was extracted through a separatory funnel with 32 mL 5% sodium bicarbonate to produce an aqueous layer and a dichloromethane layer. 7.2 mL 6 M hydrochloric acid were added to the aqueous layer until the pH was 2. The mixture was then cooled in an ice/water bath for 10 minutes. The aspirin was collected by vacuum filtration. After it dried, it yielded 0.93 g (30.9 % of original Panacetin).…
- 291 Words
- 2 Pages
Satisfactory Essays -
The Consulting Chemists Institute has been asked to analyze the drug preparation of Aspirin to find out what percentages of aspirin, sucrose, and drug preparation. The purpose of this experiment was to determine the unknown component of panacetin. Panacetin contains aspirin, sucrose, and an unknown component. Dichloromate reacts with Panacetin to produce the sucrose as an insoluble solid. Aspirin is removed from the solution by reacting with sodium bicarbonate. The aqueous layer reacts with hydrochloric acid, the unknown component can then be isolated by evaporating the solvent from the dichloromethane solution.…
- 360 Words
- 2 Pages
Satisfactory Essays -
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.…
- 1653 Words
- 7 Pages
Powerful Essays -
(b) Failing to mix the aqueous and organic layers thoroughly during the NaHCO3 extraction would lead to little to no production of aspirin precipitate. The aqueous layer contains sodium hydroxide and water, whereas the organic layer contains the dichloromethane, aspirin, and the unknown. If the HCl has nothing to react with in the aqueous layer following mixing (i.e., sodium acetylsalicylate), then little to no solid aspirin will be produced. Furthermore, more unknown would be produced than expected because aspirin would precipitate with the unknown during distillation.…
- 1439 Words
- 6 Pages
Powerful Essays -
In this experiment, the Oil of Wintergreen is put into an Erlenmeyer flask containing sodium hydroxide to create sodium salicylate. The solution is then refluxed which means that the solution will be boiled in a base, then condensed in a condenser. This replaces the carbon on the ester at carbon 1, with an oxygen atom which will have an ionic bond with a sodium anion. This yields sodium salicylate which will be acidified in methanol (CH3OH) which will remove the sodium bonded to the oxygen, and switch it to a hydrogen atom bonded to the oxygen, making an alcohol group. This new product is salicylic acid. Acetic anhydride is added to the salicylic acid to add an acetyl group to carbon 2 which will create acetylsalicylic acid…
- 516 Words
- 3 Pages
Good Essays -
Sucrose for example is insoluble in dichloromethane, while aspirin is soluble in CH2Cl2, but not in H2O. The organic compound sodium hydroxide will convert aspirin to Sodium Acetylsalicylate, which is soluble in water. Phenacetin and Actinilide are soluble in CH2Cl2, but not water. Actinilide and Phenacetin can be converted to salts by Sodium Hydroxide. The drawn out calculations on the last page will show this process being completed. Phenacetin and Acetinilide being broken down into salts helps us express that, Panacetin and dichloromethane should dissolve the aspirin and our unknown substance, but leave our sucrose behind that can be extracted by filtration. Aspirin can then be dissolved by an aqueous solution, HCL and dichloromethane. Which will then be converted to a salt. Once we dissolve the salt, our unknown solution will be left behind. The drawn out calculations on the last…
- 1948 Words
- 56 Pages
Good Essays -
To separate the sucrose the lab needed to use ~2.95 grams of Panacetin and 50 mL of dichloromethane. This mixture was then used extract the sucrose via gravity filtration. To separate the aspirin, the lab used two separate portions of sodium bicarbonate. Two different liquid layers formed, one with an aqueous solution and the other with the organic dichloromethane. The aqueous solution was then separated into one container and the dichloromethane solution into another. The lab then added HCl to the aqueous solution until it was acidic, reaching a pH ≤ 2. The aqueous solution was then cooled and the aspirin precipitate was separated. To isolate the unknown, the lab heated the dichloromethane…
- 1862 Words
- 8 Pages
Good Essays -
The acetaminophen (0.5395g) was crushed and added to a conical vial and was mixed with 2ml of methanol then shaken and let to sit till the undissolved particles settled to the bottom and transferred the liquid into a centrifuge tube using a filter-tip pipet. Repeating the process with an additional 2mL of methanol. The solvent was then centrifuged for 3 minutes until the mixture had settled into a supernatant liquid layer and a solid layer. Then in a prepared alumina column with 0.5 mL g of alumina 2mL of methanol was added to column and then the solution containing the drug. Followed by 1 mL of methanol through the top of the alumina. Half of the solution was then transferred into a small container. The remaining solvent was then evaporated in a preheated 50 C water bath and gentle air stream until 1 mL was left. The remaining solvent was then added and evaporated completely.…
- 783 Words
- 4 Pages
Good Essays -
Although the acetanilide and aspirin are both quite insoluble in water at room temperature, the sodium salt of aspirin is very soluble in water but insoluble in dichloromethane. Because aspirin is a reasonably strong acid, it can be converted to the salt, sodium acetylsalicylate, by reaction with the basic sodium hydroxide. While the two layers are thoroughly mixed, the aspirin will react with the sodium hydroxide in the bottom layer, which then migrates to the aqueous layer and can be easily separated in a separatory funnel. Adding some dilute hydrochloric acid to the aqueous solution restores free aspirin as an insoluble white solid; evaporating the solvent from the bottom layer leaves the acetanilide behind.…
- 675 Words
- 3 Pages
Good Essays -
Add 8.0 mL of dichloromethane to the 0.40 g of Panacretin and shake thoroughly, then place in a centrifuge, at three (3) speed for three (3) minutes. Extract the Sucrose and weigh using a digital scale (must be tared for accuracy). Separate the 8.0 mL of DCM to two (2) test tubes, each containing 4.0 mL of DCM. Add 4.0 mL of NaHCO3 (Sodium bicarbonate) to each of the two (2) test tubes and stir using a stirring rod until two (2) layers are visible, a thin top layer and thick-filmy bottom layer. Extract the bottom layers from the two (2) test tubes to a vial using a glass micropipette and a rubber suction cap/top and seal immediately. Conjoin the two (2) top layers to a 50 mL flask and add 1.0 mL of 6.0 M HCl to the beaker containing the solution and stir until the fizzing subsides. Test the pH of the solution with 6.0 M HCl added using pH paper, which has a color chart to analyze the results. Continue to add 1.0 mL of 6.0 M HCl until the pH of the solution is two (2) or less. Place the solution with the pH of 2 or less into an ice bath/cold water bath to form crystallization of aspirin for approximately five (5) minutes. After the five (5) minutes, establish a funnel system using a Hirsche Funnel attached to a vacuum filtration system located on/in the hood, to extract the Aspirin crystals formed from the ice bath/cold water bath. Weigh the crystals of aspirin using a digital…
- 943 Words
- 4 Pages
Better Essays -
Aspirin has a pKa of 3.49 and a melting point of 138-140 degrees Celsius. Aspirin molecule’s are insoluble in water that is why it must be sold in a solid form, there are no liquid forms of aspirin available. Aspirin is ionised in the stomach. Aspirin is easily hydrolysed as…
- 1199 Words
- 5 Pages
Good Essays -
Goggles were obtained and put on before entering the lab area. 2.0 grams of salicylic acid should be measured and placed into a 125 mL Erlenmeyer flask. 5.0 mL of acetic anhydride and 5 drops of 85% phosphoric acid was added to the Erlenmeyer flask. Drops of distilled water were added to rinse down bits of solids that were on inner wall of the flask. Mixture was heated on the hot plate for fifth-teen minutes, at 75 degrees Celsius. Two mL of distilled water was added 10 minutes into heating. Buchner funnel and filter were set up for the filtration…
- 1996 Words
- 8 Pages
Powerful Essays -
Hippocrates of Cas (460-377 B.C.), The Healer, noted that chewing leaves of willow (Salix) reduced pain, and he prescribed this remedy for women in labor. The Healer certainly did not discover this drug, which was used for centuries earlier in European folk medicine. Ancient Egyptians took an infusion of dried myrtle leaves to treat muscle pain. The myrtle leaves were also found to contain salicylic acid. Two Italians, Brugnatelli and Fontana, had in fact already obtained salicin in 1826, but in a highly impure form. Johann Buchner, professor of pharmacy at the University of Munich, isolated a tiny amount of bitter tasting yellow, needle-like crystals, which he called salicin (1828). Henri Leroux had improved the salicin extraction procedure to obtain about 30g from 1.5kg of bark (1829). An additional source of salicylic acid was found in 2835 by the German chemist Karl Jakob Lowig. This new wonder pain killer was found in Meadowsweet (Spiraea ulmaria), a wild flowering plant that grows on riverbanks over much of Europe. Raffaele Piria [an Italian chemist] then working at the Sorbonne in Paris split salicin into a sugar and an aromatic component (salicyladehyde) and converted the latter, by hydrolysis and oxidation, to an acid of crystallized colorless needles, which he named salicylic acid. (1838). the problem was that salicylic acid was tough on stomachs and a means of ‘buffering’ the compound was searched for. The first person to do so was a French chemist named Charles Frederic Gerhardt. In 1853, this man neutralized salicylic acid by buffering it with sodium (sodium salicylate) and acetyl chloride, creating acetylsalicylic acid.…
- 367 Words
- 2 Pages
Good Essays -
for the procedure I prepared a boiling bath using a hot plate, and filled a 400ml beaker with tap water. Then I got a 125ml Erlenmeyer flask and put in 2.00 grams of Salicylic acid using a scale. For the third step I added 5ml of Acetic Anhydride using a graduated cylinder. Then I added 5 drops of concentrated Sulfuric acid to the Acetic Anhydride and Salicylic acid in the Erlenmeyer flask using a dropper. I then heated the flask in the boiling bath for exactly 10 minutes. I then removed the flask and allowed it to cool on the counter for 4.5 minutes while adding 2 ml of cold distilled water dropwise. I then stirred to mix the contents. I Then added 40ml of distilled water in the solution and stirred until crystals began to form. My crystals formed in a matter of seconds. I then put the flask in a 400ml beaker of ice water to cool it down from room temperature for exactly 10 minutes to complete the crystallization process. I then collected the product in a filtration process by using filter paper and washing out the flask with distilled…
- 648 Words
- 3 Pages
Good Essays -
Paragraph 1: how is aspirin made and what are the problems with this? Energy and waste?…
- 932 Words
- 4 Pages
Powerful Essays