Expt. 11B Synthesis of Acetaminophen HW

p-aminophenol + acetic anhydride <--> Acetaminophen + acetic acid

1. Write down the "Balanced chemical equation" for the synthesis of the Acetaminophen.

Amount of solvent = (0.347g/1.0g/5.0mL) * (1mL/1.0 cm^3) Amount of solvent = (0.347g/0.2g/mL) * (1mL/1.0cm^3) Amount of solvent = 1.735 mL = 2 mL Therefore, you would need 2 mL of mixed booking solvent to crystallize 0.347g Acetaminophen

Recrystallization is the final step to purify an impure solid. Minimum amounts of "Hot, Boiling Solvent" is used as "recrystallization solvent". If the solubility of Acetaminophen in hot boiling mixed solvent of (50% methanol-50% water) is 1.0g/5.0mL mixed boiling solvent, calculate mL boiling mixed solvent needed to crystallize 0.347 g Acetaminophen. Round off your final answer to an upper level of a whole number; I.e. 4.1 mL rounds to 5 mL.

The water breaks down p-aminophenol and removed the by product acetic acid.

What is purpose of the water used in this experiment?

Sodium dithionite can decolorize a compound by heating it since p-aminophenol acquires a dark color because of oxidation.

What is the purpose of using sodium dithionite in this experiment?

We did reflux at boiling because it prevented the following solvent from boiling off since it would be heated at high temps for many minutes.

Why did you "reflux" at boiling?