Paracetamol Synthesis Lab Report

The aim of this experiment is to carry out a reaction that results in the synthesis of paracetamol. Paracetamol results when 4-aminophenol reacts with acetic anhydride. The impure, crude product will be compared to the final pure product. The percentage yield will be calculated. Paracetamol (acetaminophen) is a pain reliever, a fever reducer and an anti-inflammatory drug so it is used in many other drugs. The exact mechanism of action of it is not known but the scheme of the synthesis of paracetamol can be seen below in Figure 1. This analgesic and antipyretic drug is used to treat many conditions such as headache, muscle aches, arthritis, backache, toothaches, colds, and fevers. It can also relieve pain in mild arthritis. Paracetamol is an …show more content…
The synthesis of paracetamol is the formation of an amide (paracetamol).This happens because an amine (4-aminophenol) is acetylated with an anhydride (acetic anhydride) to produce an amide. When 4-aminophenol is put in water at room temperature with acetic anhydride (first half of Figure 1) and then heated it produces the precipitate of the amide paracetamol (second half of Figure 1). 4-aminophenol is very activating, this is why only mild conditions are needed for this synthesis. In this reaction the water serves the purpose of hydrolysing acetic anhydride to promote peptide formation with the primary amine. The mechanism is nucleophilic addition-elimination, the lone pair on N of 4-aminophenol acts as a nucleophile. This nucleophile attacks a carbon in acetic anhydride, it takes one of the two acetyl groups in acetic anhydride. The resulting compounds are 1 mol paracetamol and 1 mol acetic acid as a by-product. Paracetamol is the main product that is selectively produced because –NH2 is a better nucleophile than –OH. This can be predicted from there pKa values, the amine is the stronger base, the higher the pKa value of the conjugate acid the better the