Lab E: Adapted from Experiment #10
TA: Sudipta Biswas
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.
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. 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.
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...
Please join StudyMode to read the full document