Organic Synthesis Aspirin Aim Biology Essay

To synthesise acetylsalicylic acid, to find the pureness of acetylsalicylic acid utilizing chemical trial, and to find the per centum of output acetylsalicylic acid.Aspirin is normally used as hurting stand-in or analgetic, fever reducing agent, and as anti-inflammatory agent.

Aspirin besides is one of the most widely used for non-prescription drugs. Aspirin was found back in eighteenth century, they found aspirin from the infusion of the bark of willow trees which are utile particularly in cut downing hurting and febrility. It was so subsequently found that the active ingredient in willow bark was salicylic acid. These are the construction of the salicylic acid and acetylsalicylic acid. Although they are an effectual at cut downing hurting, it besides has unpleasant side effects which are annoyance to the liner of the oral cavity, gorge, and tummy. For aspirin image, in 1899, the Bayer company in Germany patented a drug which they named is as Aspirin, which was a alteration of salicylic acid.

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Aspirin is an acid. A mixture of salicylic acid and acetic anhydride with H2SO4 is used for acetylsalicylic acid. The synthesis of acetylsalicylic acid is an esterification, in or in other words when an acid and an intoxicant mix together in order to organize a merchandise which in this instance is an acetylsalicylic acid. Besides that, esterification can besides be reversible.

The strength of acetylsalicylic acid varies depending on their ingredients. The image below shows how aspirin is synthesized.


Preparation of Aspirin

A half-filled bath was prepared utilizing a 400-mL beaker. A few boiling rocks was added and the beaker was heated to warm the H2O.

2.00g of salicylic acid was placed in a dry 125-mL conelike flask.A 3-mL of acetic anhydride was added to the flask and the flask was swirled easy. 3 beads of concentrated sulfuric acid was besides added during the whirl of the flask. ( sulfuric acid is unsafe and baseball mitts and goggles is needed for this stairss and so on )The flask was gently swirled to blend the solution and the flash was placed in a beaker of warm H2O for 15 proceedingss. A fictile stopper was besides used to cover the flaskThe reagent was so assorted and placed in the boiling-water bath ; it was besides heated for 30 proceedingss. The solid was so dissolved and the solution was swirled once more.

The conelike flask was removed from the bath and cooled to about the room temperature.Solution was so poured into a 150-mL beaker incorporating 20 milliliter of ice H2O and the beaker was so placed in a H2O bath.A glass rod was used to blend the solution while in the H2O bath and the glass rod was besides rubbed smartly to the underside of the beaker.The solution was so poured into the Buchner funnel for filtration and the crystals were collected on the filter paper.Collected crystals were so washed with 5-mL of cold H2O and followed by 10mL of cold ethyl ethanoate.The crystals were so once more continued to dry by suction through the Buchner funnel for at least 5 proceedingss.

Re-crystallization was so performed in order to sublimate the merchandise. By utilizing a spatula, the crystals were so transferred into a 250mL beaker. 5mL of ethyl alcohol was so added. The solution was so stirred in order to fade out the crystals while the beaker was placed in a warm water-bath.After the crystals have dissolved, 15 milliliter of warm H2O was added to the intoxicant solution. Cover was so covered and crystals were formed as the solution cools. The beaker was so set to frost bath to finish the re-crystallizationThe content was so once more poured into the Buchner funnel and suction filtration was applied.The crystals should be placed between several sheets of filter paper and imperativeness dry the solid merely if the contents were wet.

Petri dish was weighed and the crystals were so added to reweigh. Weight of the acetylsalicylic acid was calculated and the per centum output so determined. ( The acetylsalicylic acid is non pure to be digest, do non devour it )

Analysis of Aspirin

One bead of 1 % Fe III chloride was added to divide trial tubings that contained a few crystals of each substance. Color was so observed ; pure acetylsalicylic acid would non demo colour, while salicylic acid or hints of it in impure acetylsalicylic acid will demo a violet colour. The strength of the coloring material qualitatively tells how much salicylic acid is present.

The acetylsalicylic acid crystals were examined under a microscope and the morphology of the crystals was recorded.The pureness of the sample determined by its thaw point scope. A howitzer and stamp was used to cut down the sample to a all right pulverization. A capillary thaw point melody was loaded with a 1-2 centimeter deepness of all right crystals.

The runing point of pure Aspirin varies between 130-135 & A ; Acirc ; & A ; deg ; C.


Preparation of AspirinTheoretical output of acetylsalicylic acid:Table below shows the informations used to cipher the theoretical output of acetylsalicylic acid.A.Mass of salicylic acid used ( g )



B.Relative molecular mass of salicylic acid ( g/mol )



Gram molecules of salicylic acid used ( mol )


D.Gram molecules of acetylsalicylic acid formed ( mol )


Tocopherol.Relative molecular mass of acetylsalicylic acid ( g/mol )


F.Expected mass of aspirin output ( g )



So, theoretical output of aspirin = 2.6100 gExperimental output of acetylsalicylic acid:The tabular array below displays the consequences obtained after the re-crystallisation procedure.A.Mass of empty Petri dish ( g )


B.Mass of Petri dish + Crystals ( g )



Mass of acetylsalicylic acid crystals ( g )


Therefore, experimental output of acetylsalicylic acid =Analysis of AspirinTest tubingColoring material before adding Fe ( III ) chlorideColoring material after adding Fe ( III ) chlorideSalicylic AcidColourless solutionDark violet solutionCommercial AspirinColourless solutionLight purple solutionPrepared AspirinColourless solutionLight purple solutionBased on the prepared acetylsalicylic acid, the ascertained thaw point for acetylsalicylic acid is at scope of 97-107 & A ; Acirc ; & A ; deg ; C. The theoretical thaw point for acetylsalicylic acid is 131-134 & A ; Acirc ; & A ; deg ; C. Each of prepared acetylsalicylic acid, salicylic acid and commercial acetylsalicylic acid was tested with Fe ( III ) chloride. Pure aspirin that tested with Fe ( III ) chloride will give no violet color solution. Purple coloring material formed when Fe ( III ) chloride combines with the phenol group that was found in salicylic acid.

Based on the above tabular array, salicylic acid gives out dark violet solution when reacted with Fe ( III ) chloride ; both commercial and prepared acetylsalicylic acid give our light violet color solution. It shows that, in commercial and prepared acetylsalicylic acid, the dross ( salicylic acid ) is present as unreacted reactant.Morphology of acetylsalicylic acidDegree centigrades: UsersHaidar TU 0311875DesktopIMG_20121011_111652.jpg


Based on the experiment, synthesis of acetylsalicylic acid involves esterification of salicylic acid.

Esterification occurs when a carboxylic acid is being reacted with an intoxicant to organize an ester. For the reaction to take topographic point, concentrated sulfuric acid is being added. Concentrated sulfuric acid Acts of the Apostless every bit accelerator as to rush up the reaction. If concentrated sulfuric acid was non added, the reaction will take a long clip to take topographic point as the reaction may take excessively long to make an equilibrium phase.

The modification reactant for the aspirin synthesis is salicylic acid. Harmonizing to stoichiometry, 1 mol of salicylic acid will respond with 1 mol of acetic anhydride to give out 1 mol of acetylsalicylic acid ( acetylsalicylic acid ) and 1 mol of acetic acid. 3mL is about to 3.0000g, so in this reaction, acetic anhydride is in surplus. Based on the computation ( mention consequences ) , the experimental consequence for output of acetylsalicylic acid is 0.

0041 g. The theoretical output of acetylsalicylic acid is 2.6100 g, in which 1 mol. Based on the information obtained, the output per centum output is. Possible causes that lead to this output per centum is mistakes done during the experiment.

Unreacted acetic acid was destroyed by the add-on of ice H2O.acetylsalicylic acid( acetylsalicylic acid )



— — — — & A ; gt ;

salicylic acid


acetic acid( ethanoic acid )Ice cold distilled H2O is added to the flask until crystallisation of acetylsalicylic acid is complete. Ice cold distilled H2O is being used as acetylsalicylic acid is indissoluble in cold H2O so, this will do aspirin non to fade out. Acetic acid and sulfuric acid are H2O soluble, so they can be removed by rinsing the acetylsalicylic acid with cold H2O. Ice cold distilled H2O is being used because acetic anhydride will break up to H2O soluble acetic acid and during the lavation, the drosss will be removed. So, pure acetylsalicylic acid is expected to acquire.Recrystallization involved in this reaction is for purification of the synthesized acetylsalicylic acid by fade outing the petroleum acetylsalicylic acid in the ethyl alcohol and pour it into beaker with warm H2O. When the solid separated, the mixture demand to be warm and allow clear solution to chill easy.

Crystalized acetylsalicylic acid can be seen when the beautiful needle-like crystal separated. Recrystallization is the primary method to sublimate organic compounds. Compounds obtained might hold drosss. So recrystallization is needed in order to take the drosss.The pureness of the synthesised acetylsalicylic acid was tested with two separate trials. First, when it was tested with Fe ( III ) chloride, a violet colourisation was formed.

This indicates that the sample had a certain sum of salicylic acid which did non respond and was non removed after purification. However, when compared to a sample of pure salicylic acid, the strength of the violet colourisation in the synthesized acetylsalicylic acid is much less than pure salicylic acid. So, it can be said that there is a comparative sum of salicylic acid hints in the synthesised acetylsalicylic acid is much less than the pure salicylic acid. When sample was compared to a sample tested with commercial acetylsalicylic acid, it is found that both had equal strength of violet colourisation. It shows that the comparative sum of salicylic acid in the synthesised acetylsalicylic acid is acceptable.

However, the sample obtained had a significantly lower runing point than the literature value of 135C. This might be due to the weak construction of the crystal than it should be or the reaction of esterification reaction was non good completed.


The reaction theory proposed in the Introduction subdivision in order to synthesize an acetylsalicylic acid is right. The reaction that takes topographic point is an esterification which requires a strong acid to continue.

For this experiment, we used concentrated sulfuric acid. It can be seen that the experimental output was lower that the theoretical output. This might had been caused by mistakes in techniques during the experiment.The Fe ( III ) chloride trial had successfully indicated the comparative sum of hint salicylic acid in the concluding merchandise and was found to be at an acceptable degree when compared to commercial acetylsalicylic acid.


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