CHEM 22161 Lab 1 :Synthesis of Medicinal Agent: Synthesis of Aspirin

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TA1

CHEM 22161

Synthesis of Medicinal Agent:

Synthesis of Aspirin

Student Name : KasunWekasinghe

Perform Date : 25-08-2015


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Date : 25-08-2014

Experiment number : 01

Experiment Title : Synthesis of Mei!inal "#ent:

Synthesis of "spirin

$b%e!ti&es :

o introd!ce single step synthetic reactions " tofa#iliari$e %ith p!ri&cation and identi&cation techni'!es of solid organic prod!cts and to introd!ce li#iting reagentand percentage yield(

Theory :Ethyl salicylate is the ester formed by the condensation of salicylic acid

and ethanol. It is a clear liquid that is sparingly soluble in

water, but soluble in alcohol and ether. Ethyl acetate is used

as a pain killer that should be taken orally where it is called

"spirin. Aspirin is used to treat pain, and reduce fever or

inflammation. It is sometimes used to treat or prevent heart

attacks, strokes, and chest pain. For the Synthesis !"#$ is used as a catalyst.

%ethyl salicylate can be produced by condensation of salicylic acid with methanol.

As a derivative of salicylic acid, it is used commonly in

e&ternal application ointments for the relief of muscle pain andcramping because it can penetrate the skin . It has a pleasant

smell it is usually called $il of 'inter#reen. #il of

wintergreen is also used as a flavoring agent in commercial

food products.

https://en.wikipedia.org/wiki/Salicylic_acidhttps://en.wikipedia.org/wiki/Methanolhttps://en.wikipedia.org/wiki/Methanolhttps://en.wikipedia.org/wiki/Salicylic_acid


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Ethyl sali!ylate Synthesis Me!hanism


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Materials: 'lass wear ( )hemicals

)onical Flask *+- m/

Salicylic acid *+.- g/

Acetic anhydride *!.- m/

0istilled 1ater

'lass rods

2eakers

2uchner Funnels

3acuum Filter

Filter "apers

"hosphoric Acid *!"#$/ *4-5,

6.-6m, +6 drops/

Ice

ot "late

Ethyl Alcohol

1atch glasses

Spatula


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(ro!eure:

"ure salicylic acid *+.- g / was pleased in a conical flask *+- m/ and Acetic

anhydride*!.- m/ was added . "hosphoric acid *4-5, 6.-6 m,+6 drops/ was added

and was mi&ed well. 7he synthesis reaction was run by heating the mi&ture in a

boiling water bath for +6 minutes with continue stirring. After +6 minutes cold

water *+6 m/ was added. After addition distilled water *$6m/ was added and the

mi&ture was mi&ed well and cooled in an ice bath. After crystal formation the

mi&ture was filtered in a 2uchner funnel using a vacuum filter. Aspirin obtained by

the crystalli8ation was dried and the weight was taken.

Few crystals of Aspirin was taken to a test tube and %ethanol *+m/ was

added and dissolved. After dissolution Fe)l! *5, 6.+-m/ was added and color

change was observed.

Impure aspirin obtained was dissolved in minimum amount of Ethyl Alcohol

and was warmed in a water bath until solution is completely dissolved. After

complete dissolution, distilled water was added until a permanent turbidity is

formed. 7he warming is continued till the solution become transparent and taken to

cool down. After crystals form crystals were filtered and dried. 0ried crystals were

collected and melting point was determined.

)esults :

7otal 1eight of the sample*Aspirin, Filter papers/ 9 :.;! g

1eight of the wet Filter papers 9 .!$ g

Salicylic acid test for aspirin is


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*al!ulation :

%olar ratio + + +

0ensity = =

%olecular weight +!4 g mol=+ +6g mol=+ +46 g mol=+

%ass +.-g +.64 g m=+ =

3olume = !.- m ="urity ;;5 ;45 =

Initial moles 6.6+64 mol 6.6!:! mol =

>eacted moles 6.6+64 mol 6.6+64 mol 6.6+64 mol

eft moles 6 6.6-- mol 6.6+64 mol

If Acetic anhydiride is the limiting >eagent

Salicylic 9 Acetic anhydiride ? + 9 +


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#bserved and measured B

7otal 1eight of the sample*Aspirin, wet Filter papers/ ? :.;! g

1eight of the wet Filter papers ? .!$ g

Final 1eight of "ure Aspirin ? *-.;!= !.!$/ g

? .-; g

"ercentage yield ? #bserved weight & +665

7heoretical weight

? *.-; g &+66 5/ @ +.;$$ g

? +!!.! 5

Dis!ussion :

In this e&periment the imiting reagent is Salicylic acid. So in

the medium an e&cess Acidic anhydride is left behind. 0ue to this

e&cess acetic anhydride solution the synthesi8ed sample containing

solution get a light pink residue. So it is important to remove any

unwanted chemicals to get purified Aspirin. So a recrystalli8ation

method is done using ethyl alcohol and water.

In this e&periment 4-5 syrus "hosphoric acid is used as a

catalyst. It help the reaction by involving in its mechanism tosynthesise aspirin. It catalyses and increase rate of esterification.

It is important to test the presence of trace amount of salicylic

acid. 7o qualitatively identify 5 Fe)l! is used. Fe)l! gives dark purple

color is observed. 2ut for this e&periment as the salicylic is the limiting

reagent so that it does not give such a color change.

7he yield of the synthesi8ed product is important to chemist as it

determines the easiest and high product rate of given compound in a

Industrial level. In this e&periment the yield of pure Aspirin was

calculated using both observed and theoretical weight values. 7he

"ercentage yield was +!!.!5. Csually it should be a value less than

+665. 2ut in this e&periment due to presence of water molecules@

wetness it becomes a higher value. So it is important to dry the aspirin

sample before finding the percentage yield.

In this e&periment the "urity of the aspirin Synthesi8ed is also

tested. It is done by using the melting point. In this e&periment themelting point observed was +!-6). by the E&perimental true value for

the aspirin %elting point is +!46). 7his slight deviation occurs due to

the presence of water molecules@wetness of aspirin sample.


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*on!lusion :

"ercentage yield is +!!.!5 and not pure Aspirin.

%elting "oint is +!-6)

Aspiri n Synthesised is not pure due to the presence of water.

)eferen!es :

http9@@[email protected] *-=64=6+-/

http9@@www.academia.edu@$4;;:@AcetylsalicylicDAcidDAspirinDSynthesis *-=64=6+-/

http9@@chemwiki.ucdavis.edu@"hysicalD)hemistry@"hysicalD"ropertiesDofD%atter@Solutions

DandD%i&tures@)aseDStudies@>E)>S7AIA7I#

CHEM 22161 Lab 1 :Synthesis of Medicinal Agent: Synthesis of Aspirin

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