The Synthesis Of Aspirin Biology Essay

The aim of this experiment is to enable us to carry on the synthesis of acetylsalicylic acid, reenforce the accomplishments of recrystallisation and reenforce the technique of runing point finding. It is carried out to organize ester from an acid and an intoxicant. The chief processs are readying of acetylsalicylic acid, recrystallisation of acetylsalicylic acid and in conclusion finding the runing point of the acetylsalicylic acid. For readying of Aspirin, acetic anhydride is added to the mensural sum of salicylic acid. Sulphuric acid is added and heated for a short period to finish reaction. Water is added one time removed from heat with add-on of cold H2O and suction filtration is carried out. As for recrystallisation of acetylsalicylic acid, collected rough merchandise prepared in readying of acetylsalicylic acid which is impure is dissolved in ethyl alcohol and hot distilled H2O is added to the solution. Once solid dissolved, weigh the ticker glass and filter paper, use the filter paper to transport out suction filtration, topographic point crystals on ticker glass, weigh the dried crystal and cipher the weight of the acetylsalicylic acid. Then, find the runing point of acetylsalicylic acid utilizing necessary setup. The per centum output was approximately 76.7 % whereas the temperature scope is between 134.2 to 136.1 ISISC.


Felix Hoffmann, a German chemist, produced a stable signifier of acetylsalicylic acid, more normally known as acetylsalicylic acid ; in 1897. Aspirin is a derivative of salicylic acid that is a mild, nonnarcotic analgetic useful in the alleviation of concern and musculus and joint achings.

Esterification is a chemical reaction used for doing esters. The reaction in which aA Carboxylic acid combines with an intoxicant in the presence of a accelerator ( normally concentrated sulfuric acid ) to organize an esterA [ CH3COOC2H5 ] is called Esterification reaction. It is reversible reaction and they merchandise sweet redolent merchandises. Esters are widely used in aroma and flavour industry. .It is besides utile in organic chemical science for the trial of intoxicants and carboxylic acid. It is used in polymer industry. Esterification reaction is used in the industry of pigments, varnishes, lacquers, medical specialties, dyes, soaps and man-made gum elastic.


Aspirin is a drug that is normally used to alleviate minor achings and hurting and other medical utilizations such as anti-inflammatory medicine. Aspirin is an ester that has high molecular weight and it non soluble in H2O hence the solid can be separated by crystallisation procedure. Synthesis of Aspirin is known as esterification.

Acetic anhydride is uses as it is inexpensive and forms a byproduct, acetic acid which is non caustic and can be recovered to do more acetic anhydride unlike other acetylizing agents that besides can be used.

All add-on of chemicals to aspirin is done in the fumehood. Fumehood is a local airing device that is designed to restrict exposure to risky or noxious exhausts, bluess and dust. A fume goon is a big piece of equipment five enclosed sides of a work country, the underside of which is most normally located at a standing work tallness.

The three chief intent of the fumehood are as follows:

Protect the user transporting out the experiment

Protect the merchandise and experiment from unsought reactions.

Protect the environment from emanation of harmful merchandises.

In the consequences, we calculate the per centum output and the thaw temperature. Percent output is calculated by ( Mass of dried, recrystallised acetylsalicylic acid ) ? ( Expected mass of acetylsalicylic acid ) . In this experiment, the per centum output is 76.7 % output which shows that it is about to the full pure and contains lesser drosss. The temperature is set to 100 ISC and so bit by bit heated up to find the thaw point. The theory runing point is 140 ISC and the experiment runing point scope is 134.2 ISC to 136.1 ISC.


Preparation of Aspirin

2.4g of salicylic acid is measured in a 100ml conelike flask and is recorded.

6mL of acetic anhydride is added to the salicylic acid to the flask in the fumehood.

3 to 4 beads of conc. Sulphuric acid is added to the mixture and is swirled. Mixture is heated for 10 to 15 min to finish reactions.

Suction filtration is carried out and the gathered petroleum merchandise after rinsing it a small with cold H2O.

Extra 40mL of cold H2O is added. Stir and rub mixture to bring on crystallization.

After taking from heat, 1 milliliter of distilled H2O is carefully added to the mixture while it is hot to break up the extra acetic anhydride.

Recrystallisation of Aspirin

Crude merchandise collected was dissolved in approx 5mL of ethyl alcohol in a 100mL conelike flask. Warmed.

Approx 30mL of hot distilled H2O is added to the solution. If solid offprints, warm boulder clay solid dissolved wholly.

Solution allowed to chill down.

The dried crystal is weighed together with the filter paper and ticker glass. Weight is recorded.

Suction filtration is carried out to obtain the recrystallised merchandise utilizing the weighed filter paper.

A clean and dry ticker glass is measured together with a filter paper and the weight is measured and recorded.

Weight of the dried, recrystallised acetylsalicylic acid, the expected output of acetylsalicylic acid from the sum of salicylic acid, the per centum output of dried, recrystalllised acetylsalicylic acid is measured.

Melting point is determined by utilizing the optimelt runing setup.

Consequences and Calculations

Preparation and recrystallisation of Aspirin


Mass of salicylic acid ( a ) = 2.40g

Mass of filter paper & A ; ticker glass ( B ) = 32.96g

Mass of dried, recrystallised acetylsalicylic acid, filter paper & A ; ticker glass ( degree Celsius ) = 34.41g

Mass of dried, recrystallised acetylsalicylic acid ( vitamin D ) = ( degree Celsius ) – ( B )

= 34.41 – 32.96

= 1.45g

Percent output

Number of moles of salicylic acid used ( vitamin E ) = mass/mr

= 2.40/138

= 0.017391 mol

( mol wt of salicylic acid = 138 )

Expected figure of moles of acetylsalicylic acid ( degree Fahrenheit ) = 0.010507 mol

Expected mass of acetylsalicylic acid ( g ) = 0.01739 ten 180 = 3.1302 g

( mol wt = 180 )

Percent output = ( vitamin D ) / ( g ) A- 100 %

= 46.3 %

Melting Point

Temperature scope = 134.2 ISC to 136.1 ISC


White, thin, flakey crystals


My Consequences

Harmonizing to my experiment and the consequences, one conclude that my end merchandise is non truly pure. This can be seen from the computation made based on my experiment utilizing this expression,

Percent output is the sum of substance we have obtained in entire in the experiment. The experimental output per centum is different from the theoretical per centum is because there is loss of merchandise frequently happening during the isolation and purification stairss. The percent output of the acetylsalicylic acid obtained from my experiment is 46.3 % output. The higher the output per centum, the higher the pureness of the acetylsalicylic acid will be. Therefore, harmonizing to my consequences, the acetylsalicylic acid obtained is comparatively impure. However, the low per centum output can besides intend that the reactant has non reacted wholly or the reaction is non complete. However there is besides another possibility for the lower per centum output value. It is the add-on of H2O when transporting out suction filtration. As we have to rinse down the crystals before we carry out the suction filtration, some crystals might hold dissolved. Hence, the sum of H2O we use to rinse down the crystals during suction filtration might hold affected the per centum output excessively.

The acetylsalicylic acid crystals are packed into the little capillary tubings and do certain they are all compressed without air spreads. Then they are placed into the thaw setup. The thaw temperature scope of acetylsalicylic acid harmonizing to my experiment is between 134.2 ISC to 136.1 ISC. The theoretical thaw temperature is 140 ISC. Since the values are rather nigh, this shows that the acetylsalicylic acid we obtained is quite pure and hence contained less drosss.

From both the computations, I can measure that the acetylsalicylic acid is pure to a big extent nevertheless due to some mistakes or improper techniques ; the per centum output is non up to outlook and uncomplete reactions might besides be one of the grounds.

Experimental Mistakes

There were some experimental mistakes that have caused fluctuation in my consequences compared to the theoretical solutions.

First, after the obtaining the rough merchandise from the first suction filtration, we had to reassign it to the conelike flask to transport out recrystallisation. During this procedure, there were some crystals that got blown off by the air current and some crystals poured on the desk excessively. Hence this might hold affected the per centum output excessively.

Therefore, I had learnt that all wind beginning must be switched off and be kept off from when transporting out this procedure to guarantee truth in consequences.

Second, one time we have dissolved and during the 2nd unit of ammunition suction filtration in effort to obtain the pure acetylsalicylic acid, we forgot to utilize 2 filter documents but alternatively use merely one on the Buchner funnel. Hence, due to the force per unit area, the filter paper torus and our rough merchandise entered the filter flask that was incorporating the drosss and other liquid. Therefore we had to suction filter the whole mixture in the filter flask and hence, this might hold led to presence of more drosss or lose in merchandise. This might hold affected the consequences.

Therefore, from this I learn that I must be more watchful when I carry out suction filtration to avoid unneeded fuss and inaccuracy of consequences and computation.


From this experiment, I have learnt how to transport out suction filtration in the right manner and to be cautious at all clip when managing chemicals and so on. The major experimental findings are that, truth and heed is really of import in this experiment to obtain acetylsalicylic acid that is pure. However, there will be some environmental effects that will still impact the experiment to a little extent.

Finally the aim of the experiment is met and the consequences were acceptable as it is rather accurate.