SYNTHESIS OF THE PHARMACEUTICAL ASPIRIN
SYNTHESIS OF THE PHARMACEUTICAL ASPIRIN (ACETYLSALICYLIC ACID)
AIM:
The aim for this experiment was to synthesise a small amount of aspirin with salicylic acid as the starting product and sulphuric acid as the catalyst. The product obtained from this reaction will be impure and will need to be purified. This will be done by recrystallization. We will then record the products’ melting point and calculate the yield in order to determine the degree of purity of the aspirin sample.
Diagrammatic scheme for the reaction:
OBSERVATIONS:
When 5g of salicylic acid, 7.5 cm3 of ethanoic anhydride and 3 drops of concentrated sulphuric acid were mixed, a white milky solution was formed. This solution was heated and a yellow liquid formed. 75 cm3 of distilled water was added and the yellow liquid became cloudy with white precipitates visible in the solution. These white precipitates were collected by vacuum filtration and in the end we had sugar-like crystals.
CALCULATION OF THE CRUDE YIELD:
Mass of crude product = 11.58g
Theoretical value: 5g/ (138g/mol)*(180g/mol) = 6.522
Percentage yield of crude product: 11.58g/ (6.522g)*100 = 177.6%
CALCULATION OF THE PURIFIED YIELD:
Mass of purified product: 5.98g
Percentage yield of purified product: 5.98g/ (6.522g)*100 = 91.69% MELTING POINT RANGE OF THE STARTING SALICYLIC ACID:
159 – 160°C
LITERATURE VALUE:
158 -161°C http://www.sigmaaldrich.com/catalog/product/sigma/s7401?lang=en®ion=GB MELTING POINT RANGE OF THE RECRYSTALISED PRODUCT:
130.5 - 131°C
LITERATURE VALUE:
134 - 136°C http://www.sigmaaldrich.com/catalog/product/sigma/a2093?lang=en7region=GB COMMENT ON THE SUCCESS OF THIS REACTION:
The crude product had a percentage yield of 177.6%. This is over 100% and my guess is that this is due to the presence of impurities in the crude product and maybe there was human error during the weighing of the crude product. The percentage yield of the pure product was 91.69%, this seems like a justifiable figure. Our melting point
AIM:
The aim for this experiment was to synthesise a small amount of aspirin with salicylic acid as the starting product and sulphuric acid as the catalyst. The product obtained from this reaction will be impure and will need to be purified. This will be done by recrystallization. We will then record the products’ melting point and calculate the yield in order to determine the degree of purity of the aspirin sample.
Diagrammatic scheme for the reaction:
OBSERVATIONS:
When 5g of salicylic acid, 7.5 cm3 of ethanoic anhydride and 3 drops of concentrated sulphuric acid were mixed, a white milky solution was formed. This solution was heated and a yellow liquid formed. 75 cm3 of distilled water was added and the yellow liquid became cloudy with white precipitates visible in the solution. These white precipitates were collected by vacuum filtration and in the end we had sugar-like crystals.
CALCULATION OF THE CRUDE YIELD:
Mass of crude product = 11.58g
Theoretical value: 5g/ (138g/mol)*(180g/mol) = 6.522
Percentage yield of crude product: 11.58g/ (6.522g)*100 = 177.6%
CALCULATION OF THE PURIFIED YIELD:
Mass of purified product: 5.98g
Percentage yield of purified product: 5.98g/ (6.522g)*100 = 91.69% MELTING POINT RANGE OF THE STARTING SALICYLIC ACID:
159 – 160°C
LITERATURE VALUE:
158 -161°C http://www.sigmaaldrich.com/catalog/product/sigma/s7401?lang=en®ion=GB MELTING POINT RANGE OF THE RECRYSTALISED PRODUCT:
130.5 - 131°C
LITERATURE VALUE:
134 - 136°C http://www.sigmaaldrich.com/catalog/product/sigma/a2093?lang=en7region=GB COMMENT ON THE SUCCESS OF THIS REACTION:
The crude product had a percentage yield of 177.6%. This is over 100% and my guess is that this is due to the presence of impurities in the crude product and maybe there was human error during the weighing of the crude product. The percentage yield of the pure product was 91.69%, this seems like a justifiable figure. Our melting point