Crude Acetaminophen Synthesis
Lab E: Adapted from Experiment #10
TA: Sudipta Biswas
Tuesday, 1:05pm
10/25/11
Sarah Kempkes
Abigail Scherer
Abstract:
The purpose of this experiment was to create and obtain pure acetaminophen. p-aminophenol and acetic anhydride were used to create acetaminophen and acetic acid. The acetic acid mixed with acetaminophen created an impure sample, which was purified through the addition of a water/methanol solution. The percent recovery of acetaminophen from the impure sample to the pure sample was 76%. The melting point of the pure sample was 167C - 169C.
Introduction:
Formulation of acetaminophen involves treating an amine with an acid anhydride to give rise to an amide. In this experiment, p-aminophenol, the amine, is treated with acetic anhydride to form acetaminophen, the amide.
The crude acetaminophen was expected to be dark in color. This was due to the fact that the impurities were formed from oxidation of the starting phenol. The intensity of this was enough to impart color to the crude acetaminophen.
Crude acetaminophen can be purified using the solid-liquid separation technique of ccrystallization where there is a transfer of the solute from the liquid solution to a pure solid crystalline phase. The pure acetaminophen will result in a white color, indicating impurities had been eliminated. …show more content…
The purity of a substance can be deciphered from its melting point. The melting point of a substance is fundamentally independent of atmospheric pressure. The melting point of a substance is lowered and broadened by the presence of impurities. The amount of decrease in melting point is dependent on the nature and the concentration of the impurities. Thus, the melting point of the pure acetaminophen would be expected to be higher than that of the crude acetaminophen.
Results:
Isolation of crude acetaminophen was retrieved with a mass of approximately .009g from the reaction mixture. The crude acetaminophen obtained was a dark brown in color and appeared opaque. From here a calculation of the percent yield of the acetaminophen was obtained by comparison of the original 0.150 g of p-aminophenol at the start of the procedure.
% Yield=0.0090.150=0.062g of crude acetaminophen
Crystallization of crude acetaminophen was performed to obtain pure acetaminophen. The substance was white in color. A melting point and % yield of pure acetaminophen was calculated as follows:
% Yield=0.0620.047 = 0.760 g of pure acetaminophen
% Recovery of Pure Acetaminophen = .76g X 100 = 76%
Melting point = 167°C – 169 °C
Materials/Methods: Part 1: 0.15 grams of p-aminophenol was weighed and placed in a 5mL conical vial.
Also added was 0.45mL water and 0.165mL acetic anhydride and a magnetic spin vane. An air condenser was attached to the vial and it was heated on an aluminum block, with a temperature maintained at 120C. After the solution dissolved, it was heated an extra 20 minutes to allow the reaction to go to completion then cooled back to room temperature. An ice bath was used to encourage crystal growth. The crystals were removed and centrifuged, then placed on a pre-weighed watch glass to dry and weigh. Percent recovery was found. A small sample was set aside for melting
point. Part 2: The crystals were then placed in a clean 5mL conical vial and mixed with a 50/50 solution of water and methanol that was heated separately on an aluminum block. The solution was then cooled to room temperature and then placed in an ice bath for about 10 minutes. The crystals that appeared were then centrifuged and placed on a clean, pre-weighed watch glass to allow them to dry. Percent recovery was found. The melting point of the sample was taken, as was the melting point of the crude sample from part 1 and compared.
Discussion: The percent recovery of crude acetaminophen compared to that of pure acetaminophen was found to be 76%. This means that 76% of the acetaminophen from the crude sample was recovered by itself in the pure sample. The percent recovery of acetaminophen of the overall reaction was not required. The melting point of the final pure sample of acetaminophen was found to be 167C - 169C. The theoretical melting point of acetaminophen is 169.5C - 171C. The pure sample is very close to the theoretical sample implying that the final product was almost pure acetaminophen. The few degrees of difference indicate that there was still some crude product left over in the sample, lowering its melting point. This lab had a great deal of errors in it. The thermometer used to detect the temperature in part 1 of the lab was placed in a beaker of water. This turned out to be an inaccurate measure of the heat on the aluminum block as it said the temperature was only 100C, but when we put the thermometer on the aluminum block the temperature shot up to around 220C. We tried to reduce the temperature, but it was already too hot and the air condenser burst off and broke. This immensely high heat also burned our sample, leaving no way to finish the experiment. We used data from another group to get the results above. Acetaminophen was successfully prepared in this experiment by the group which provided the valid data.
TA: Sudipta Biswas
Tuesday, 1:05pm
10/25/11
Sarah Kempkes
Abigail Scherer
Abstract:
The purpose of this experiment was to create and obtain pure acetaminophen. p-aminophenol and acetic anhydride were used to create acetaminophen and acetic acid. The acetic acid mixed with acetaminophen created an impure sample, which was purified through the addition of a water/methanol solution. The percent recovery of acetaminophen from the impure sample to the pure sample was 76%. The melting point of the pure sample was 167C - 169C.
Introduction:
Formulation of acetaminophen involves treating an amine with an acid anhydride to give rise to an amide. In this experiment, p-aminophenol, the amine, is treated with acetic anhydride to form acetaminophen, the amide.
The crude acetaminophen was expected to be dark in color. This was due to the fact that the impurities were formed from oxidation of the starting phenol. The intensity of this was enough to impart color to the crude acetaminophen.
Crude acetaminophen can be purified using the solid-liquid separation technique of ccrystallization where there is a transfer of the solute from the liquid solution to a pure solid crystalline phase. The pure acetaminophen will result in a white color, indicating impurities had been eliminated. …show more content…
The purity of a substance can be deciphered from its melting point. The melting point of a substance is fundamentally independent of atmospheric pressure. The melting point of a substance is lowered and broadened by the presence of impurities. The amount of decrease in melting point is dependent on the nature and the concentration of the impurities. Thus, the melting point of the pure acetaminophen would be expected to be higher than that of the crude acetaminophen.
Results:
Isolation of crude acetaminophen was retrieved with a mass of approximately .009g from the reaction mixture. The crude acetaminophen obtained was a dark brown in color and appeared opaque. From here a calculation of the percent yield of the acetaminophen was obtained by comparison of the original 0.150 g of p-aminophenol at the start of the procedure.
% Yield=0.0090.150=0.062g of crude acetaminophen
Crystallization of crude acetaminophen was performed to obtain pure acetaminophen. The substance was white in color. A melting point and % yield of pure acetaminophen was calculated as follows:
% Yield=0.0620.047 = 0.760 g of pure acetaminophen
% Recovery of Pure Acetaminophen = .76g X 100 = 76%
Melting point = 167°C – 169 °C
Materials/Methods: Part 1: 0.15 grams of p-aminophenol was weighed and placed in a 5mL conical vial.
Also added was 0.45mL water and 0.165mL acetic anhydride and a magnetic spin vane. An air condenser was attached to the vial and it was heated on an aluminum block, with a temperature maintained at 120C. After the solution dissolved, it was heated an extra 20 minutes to allow the reaction to go to completion then cooled back to room temperature. An ice bath was used to encourage crystal growth. The crystals were removed and centrifuged, then placed on a pre-weighed watch glass to dry and weigh. Percent recovery was found. A small sample was set aside for melting
point. Part 2: The crystals were then placed in a clean 5mL conical vial and mixed with a 50/50 solution of water and methanol that was heated separately on an aluminum block. The solution was then cooled to room temperature and then placed in an ice bath for about 10 minutes. The crystals that appeared were then centrifuged and placed on a clean, pre-weighed watch glass to allow them to dry. Percent recovery was found. The melting point of the sample was taken, as was the melting point of the crude sample from part 1 and compared.
Discussion: The percent recovery of crude acetaminophen compared to that of pure acetaminophen was found to be 76%. This means that 76% of the acetaminophen from the crude sample was recovered by itself in the pure sample. The percent recovery of acetaminophen of the overall reaction was not required. The melting point of the final pure sample of acetaminophen was found to be 167C - 169C. The theoretical melting point of acetaminophen is 169.5C - 171C. The pure sample is very close to the theoretical sample implying that the final product was almost pure acetaminophen. The few degrees of difference indicate that there was still some crude product left over in the sample, lowering its melting point. This lab had a great deal of errors in it. The thermometer used to detect the temperature in part 1 of the lab was placed in a beaker of water. This turned out to be an inaccurate measure of the heat on the aluminum block as it said the temperature was only 100C, but when we put the thermometer on the aluminum block the temperature shot up to around 220C. We tried to reduce the temperature, but it was already too hot and the air condenser burst off and broke. This immensely high heat also burned our sample, leaving no way to finish the experiment. We used data from another group to get the results above. Acetaminophen was successfully prepared in this experiment by the group which provided the valid data.