To synthesise the drug acetylsalicylic acid, the pureness of prepared of acetylsalicylic acid is determined by a chemical trial. In add-on, the per centums of acetylsalicylic acid made are determined ( CHM 1024 Organic Chemistry, practical manual ) .


Aspirin besides know as acetylsalicylic acid, in the history of medical specialty, acetylsalicylic acid is the first drugs that of all time come into common use which as medical interventions worldwide. It is known as a hurting slayer, febrility reducing agent and anti-inflammatory agent. As a affair of fact, an anti-inflammatory agent has become a widely known and utilised intervention for arthritis. ( 1 )

Aspirin is besides an anti-clotting agent. It is because it can suppressing the production of thromboxane which will adhere with thrombocyte to make a spot of damaged walls of capillaries and thrombocyte will go big adequate to barricade the blood flow, locally and besides downstream, acetylsalicylic acid besides can utilize in long-run at low doses for assisting prevent bosom onslaughts, shots and besides blood coagulum formation. ( 2 )

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The synthesis of acetylsalicylic acid is really an esterification reaction. By acerb derivative, salicylic acid is treated with acetic anhydride, which will giving a chemical reaction that alteration hydroxyl group in salicylic acid into ester group ( R-OH > R-OCOCH3 ) . This esterification reaction will give aspirin every bit good as acetic group which is a by-product in this reaction. This procedure is speed up by utilizing accelerator which is concentrated sulfuric acid. ( 3 )

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Figure 1: salicylic acid reacts with acetic anhydride to organize acetyl salicylic acid which is aspirin and a byproduct, acetic acid.

Overdose of acetylsalicylic acid will take to acute or chronic toxic condition. If a individual big dosage of acetylsalicylic acid is taken so it is acute toxic condition ; if taking higher than normal dosage of acetylsalicylic acid over some period of clip so it is chronic toxic condition. The mortality rate for ague overdose is low, but for chronic overdose is more by and large fatal. Other than that, overdose of acetylsalicylic acid besides will hold some bad side effects which is stomach aching and concern. These side effects can be reduced through the add-on of buffer solution.

The presence of any unreacted or extra salicylic acid is detect by 1 % Fe III chloride ( FeCl3 ) . As salicylic acid got phenol group, the FeCl3 trial will giving a positive consequence that show color alteration to violet coloring material if there have molecule possessing phenol group. Hence, the commercial acetylsalicylic acid will given negative consequence because it does non hold phenol group with it.


When salicylic acid reacts with acetic anhydride will give aspirin and acetic acid.


Preparation of acetylsalicylic acid

A bath was prepared by utilizing 400mL beaker was filled with half with H2O and it was heated until it boiling.

2.00g of salicylic acid was weighed and placed in 125mL dry conelike flask. This measure was used to cipher the theoretical output of acetylsalicylic acid.

3mL of acetic anhydride was measured and added into the conelike flask with gently swirled. The 3 beads of concentrated sulfuric acid was added into the flask during twirling. After that, the conelike flask was placed in a beaker of warm H2O for 15 proceedingss.

The reagents were assorted and so placed in a beaker of boiling-water bath for 30mins until the solid was wholly dissolved. The solution was swirled on occasion.

The conelike flask was removed from the bath and it was cooled down to about room temperature which is 27 & A ; deg ; C.

The solution was easy poured into a 150mL beaker which incorporating 20mL of ice H2O and assorted wholly so placed in an ice bath.

During the ice bath, glass rod was used to blend the solution and rubing along the underside of the beaker smartly. ( be cognizant no to jab a hole through the beaker. )

The crystal were formed and collected by utilizing Buchner funnel through filtration and suction.

The crystals were washed by 5mL of cold H2O and the followed by 5mL of cold ethyl ethanoate.

Suction was continued for at least 5mins for drying the crystals.

The crystals were transferred to a 250mL beaker by utilizing spatula and 5 beads of ethyl alcohol were added into the beaker. The beaker was stirred and warmed inside a H2O bath to fade out the crystal. Re-crystallization procedure was performed.

After the crystals dissolved 25mL warm H2O was added to the intoxicant solution. The solution was let to chill down and so crystals were formed. Once the crystallisation started, the beaker in the ice bath was set to finish the re-crystallization.

The contents in the beaker were poured into Buchner funnel and suction and filtration was applied.

Filter documents were used to take all the extra H2O by traveling the crystals on the filter paper anf placed it between several sheets of filter documents and gently pressed to dry the solid.

Petri dish was weighed. Then crystal added on it and reweigh of petri dish. The weight of the purified acetylsalicylic acid was obtained by simple computation and so this is used to obtain the per centums output of acetylsalicylic acid.

Analysis of Aspirin.

Compare the quality of the synthesized acetylsalicylic acid with commercial acetylsalicylic acid and salicylic acid.

1 % of Fe III chloride was added to divide the trial tubing incorporating aspirin crystals of each substance. The coloring material was observed. There will be no coloring material showed if acetylsalicylic acid is pure. Purple coloring material was showed if salicylic acid or hints is present in impure acetylsalicylic acid. Then the strength of coloring material qualitatively tells how much salicylic acid was present.

The acetylsalicylic acid crystals were observed under the microscope and were drawn on the consequence sheet.

The pureness of sample was tested by finding its thaw point scope. Reduce the sample to a all right pulverization by utilizing howitzer and Pestle. A runing point capillary tubing with 1-2cm deepness of all right crystals was loaded. The runing point degree Fahrenheits purified aspirin varies between 130-135 & A ; deg ; C, temperature was noticed at the acetylsalicylic acid begins to run and the sample has wholly melted.

Safety Precaution

When covering with acetic anhydride and sulfuric acid need to utilize baseball mitts and do it in fume goon, because acetic anhydride will annoy the eyes ; sulfuric acid will do burn to clamber because it is concentrated and caustic. The aspirin prepares is non pure plenty and can non utilize as a drug every bit good as can non devour.


Table 1: Iron ( III ) Chloride, FeCl3 trial on acetylsalicylic acid



Commercial acetylsalicylic acid

no coloring material

Purified acetylsalicylic acid


Table 2: Experimental consequences



1. Weight of the salicylic acid


2. Weight of petri dish + filter paper


3. weight of aspirin + petri dish + filter paper


4. Weight of aspirin [ 3-2 ]


5. Melting point of purified acetylsalicylic acid

144 & A ; deg ; C-172 & A ; deg ; C

6. Melting point of commercial acetylsalicylic acid

132.8 & A ; deg ; C-138.9 & A ; deg ; C


The molar molecular mass of acetylsalicylic acid = 180g/mol

The molar molecular mass of salicylic acid = 138g/mol

The molar molecular mass of acetic anhydride = 102g/mol

Number of moles of salicylic acid, C7H6O3

= ( weight of salicylic acid ) / ( molar molecular mass of salicylic acid )

= 2.0100g / ( 138g/mole ) = 0.0146 mole

Number of moles of acetic anhydride, C4H6O3

= ( weight of acetic anhydride ) / ( molar molecular mass of acetic anhydride )

= 3.246g / ( 102g/mole ) = 0.0318 mole

By comparing the figure of mole of the salicylic acid and acetic anhydride, the mole of salicylic acid is lesser. Therefore, the acetic anhydride is in surplus. Hence the modification agent in this experiment is salicylic acid.

By comparing of the chemical equations:

C7H6O3 + C4H6O3 i? C9H8O4 + C2H4O2

one mole of C7H6O3 reacts with one mole of C4H6O3

to bring forth one mole of C9H8O4 and one mole of C2H4O2

Theoretical output of aspirin = 0.0146 mole – ( 180g/mole )

= 2.628g

Actual output of aspirin = 0.8953g

Percent output of the acetylsalicylic acid

= ( existent output of acetylsalicylic acid ) / ( theoretical output of acetylsalicylic acid ) -100 %

=0.8953g/2.628g – 100 %

=34.07 %

Diagram of Commercial Aspirin

Degree centigrades: UsersAliceDocumentsBluetooth FolderIMG-20121011-WA0000.jpg


In this experiment, aspirin crystals obtained were white crystals and is in pure signifier which is white crystalline solid. Then the per centums output of acetylsalicylic acid obtained was 34.07 % , and there are so many grounds that could non acquire a 100 % output of the acetylsalicylic acid.

The merchandise can be lost while transferred from one container to another. Other than that, when during suction through filtration, some of the acetylsalicylic acid might stay in the dissolved filtrate and this causes the output of the merchandise to be less than theoretical output. Besides that, when weighing salicylic acid and acetylsalicylic acid there might hold zero mistake on the deliberation machine and this will besides impact the consequence and inaccuracy in the output of the merchandise.

The runing point of purified acetylsalicylic acid obtained will hold mistake be found every bit good, because the instrument that utilizing for mensurating the runing point of acetylsalicylic acid was non wholly cool down during mensurating the crystals. Furthermore, acetylsalicylic acid might incorporate drosss that causes runing point to be higher or lower than the existent thaw point.

During the Iron ( III ) Chloride trial, the commercial acetylsalicylic acid showed no coloring material alteration, it is because there have no drosss and suited for consumption, but for the purified acetylsalicylic acid it gave a positive consequences which mean the solution turns violet coloring materials due to the drosss in the merchandise and it proved that the purified acetylsalicylic acid is non suited for consumption.

This experiment was required 3 beads of concentrated sulfuric acid, because concentrated sulfuric acid was act as a accelerator for rushing up the reaction without impacting the consequence. The reaction will still take topographic point if the concentrated sulfuric acid were omitted.

This experiment used ice H2O during the work up is due to the feature of acetylsalicylic acid. Aspirin is indissoluble in H2O and cold H2O will cut down the solubility of acetylsalicylic acid in H2O and it can be isolated when undergo suction through filtration with chilled reaction solution. Then the H2O is used to hydrolyze the acetic anhydride to acetic acid and can be easy removed by filtration. Therefore, all the drosss can be removed.

The rule of recrystallization is the sum of solute that can he fade out by a dissolver increases with temperature. Recrystallization merely works when a proper dissolver used. In this experiment the dissolver that used to fade out the drosss is ethyl ethanoate and so utilizing hot filtration to take inpurities.

The pureness of the synthesized acetylsalicylic acid was tested by FeCl3, if there is color alteration ( violet coloring material ) that means there have drosss in acetylsalicylic acid. The pureness of acetylsalicylic acid was determined by runing point. In this experiment the thaw scope for acetylsalicylic acid is 144 & A ; deg ; C-172 & A ; deg ; C which is higher than commercial acetylsalicylic acid which is132.8 & amp ; deg ; C-138.9 & A ; deg ; C, intending that acetylsalicylic acid obtained in this experiment contained drosss.

There have some betterment for this experiments as in used all the salicylic acid pulverization and ensured that there is no bead on the tabular array. During reassigning the reactants from one to another container make certain that there is no any staying in the container. Furthermore, during filtrating the acetylsalicylic acid by utilizing the suction guarantee that all holes on the Buchner funnel are covered for forestalling the decrease of output merchandise.


This experiment was supported the hypothesis suggested. When salicylic acid reacts with acetic anhydride will give acetylsalicylic acid which known as acetylsalicylic acid. In this experiment, the modification agent is salicylic acid. The runing point scope for the acetylsalicylic acid obtained is 144 & A ; deg ; C-172 & A ; deg ; C, it is because it contains drosss. The theoretical output of acetylsalicylic acid is 2.628g, but the existent output of acetylsalicylic acid obtained is 0.8953g. hence, the per centum output of acetylsalicylic acid is 34.07 % .


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