Synthesis of Asprin

"SYNTHESIS of ASPIRIN"

PURPOSE:

In this experiment is to obtain aspirin. Aspirin is prepared by acetylated salicylic acid I a process called esterification. Esterification is the reaction of the carboxyl (-COOH) group, and the -OH group to form a carboxyl ate ester group. In this case the source of the -OH group is the phenolic -OH attached to the ring of the salicylic acid. The acetyl group comes from acetic acid anhydride, and the reaction is catalyzed by phosphoric acid. Recrystalization is used in a mixed solvent of ethanol and water to purify the crude aspirin. Melting point determines the relative purity of obtained aspirin.

STRUCTURE EQUATION for the SYNTHESIS of ASPRIN:

PRODECURE:

Refer to the Mohrig Lab-book p. 41-49

RESULTS:

Amount of Methyl Salicylate = 1.008 g

Amount of Acetic anhydride = 2.0 ml

Mass of Aspirin = 0.425 g

Melting Point Range = 115- 122 0C

OBSERVATIONS:

% Yield of Aspirin = [actual yield/ theoretical yield] x 100

Mass of Obtained Aspirin = 0.425

diagram showing the chemical synthesis of aspirin

Diagram showing the Kolbe-Schmitt reaction used in...

Acetyl salicylic acid chemical structure

g

% Yield of Aspirin = [0.425 / 1.008] x 100 = 42.16 %

Aspirin was obtained in a 42.16 % Yield from salicylic acid. Relatively pure white crystals of Aspirin were obtained. The purity was tested with melting range.

CHEMICALS USED:

ACETYLSALICYLIC ACID (ASPIRIN):

Molecular Formula: C9H8O4

Molecular Weight: 180.154

Melting Point: 135-136 0C

Boiling Point: 1400C

SALICYLIC ACID:

Molecular Formula: C7H6O3

Molecular Weight: 138.1226

Density: 1.44

Vapor Density: 4.8

Melting Point: 158- 162 0C

Boiling Point: 2110C at 20 mmHg

ACETIC ANHYDRIDE:

Molecular Formula: C4H6O3

Molecular Weight: 102.088

Density: 1.075 g/ml

Melting Point: -73.1 0C

Boiling Point: 139.50C

ACETIC ACID:

Molecular Formula: C2H4O2

Molecular Weight: 60.052

Density: 1.0497 g/ml

Melting Point:16.6 0C

Boiling Point: 117.9 0C

CONCLUSION:

Salicylic acid was converted into acetylsalicylic acid - Aspirin, which was obtained in 42.16 %...