Préparation de l'Acétaminophène (Paracétamol)

Synthèse d'un analgésique par formation d'une liaison amide

Organic Synthesis Advanced (University) 80 min ~$18,00

Objectif

Synthétiser l'acétaminophène (paracétamol) par acétylation du p-aminophénol avec l'anhydride acétique, démontrant la formation de liaisons amide.

Contexte

Acetaminophen is one of the world's most widely used over-the-counter analgesics. Its synthesis involves the reaction of p-aminophenol with acetic anhydride to form an amide bond. The reaction is selective for the amine group over the phenol group under mild conditions.

Avertissements de sécurité

  • Acetic anhydride is corrosive and has a strong odor
  • p-Aminophenol can cause skin irritation
  • Do not consume the product
  • Work in a fume hood

EPI requis

goggles gloves lab_coat

Matériaux

  • p-Aminophenol (1.5 g)
  • Acetic anhydride (2 mL)
    Corrosive
  • Distilled water (100 mL)
    Ice-cold for crystallization
  • Acetone (10 mL)
    For recrystallization

Équipement

250 mL Erlenmeyer flask Hot water bath Buchner funnel Filter flask Melting point apparatus Ice bath

Procédure

1

Dissolve 1.5 g p-aminophenol in 15 mL distilled water in the Erlenmeyer flask. Warm gently if needed.

5 min Handle p-aminophenol with gloves
2

Add 2 mL acetic anhydride to the solution. Stir vigorously for 10 minutes.

10 min Fume hood — pungent vapors
3

Heat the mixture in a water bath at 70°C for 10 minutes to complete the reaction.

12 min
4

Cool the mixture in an ice bath until crystals form.

15 min
5

Collect crude product by vacuum filtration. Wash with cold water.

8 min
6

Recrystallize from hot water or acetone/water mixture. Cool slowly for larger crystals.

15 min
7

Collect purified crystals. Dry and determine melting point (pure: 168-170°C).

10 min
8

Calculate percent yield.

5 min

Résultats attendus

White crystalline solid with melting point 167-170°C. Typical yield is 70-85%. The product should be pure white; discoloration indicates impurities from p-aminophenol oxidation.

Nettoyage

Do not consume the product. Dispose of organic waste properly. Rinse all glassware.

Frequently Asked Questions

What is the objective of Préparation de l'Acétaminophène (Paracétamol)?
Synthétiser l'acétaminophène (paracétamol) par acétylation du p-aminophénol avec l'anhydride acétique, démontrant la formation de liaisons amide.
How difficult is Préparation de l'Acétaminophène (Paracétamol)?
This experiment is rated as Advanced (University). It takes approximately 80 minutes to complete.
What safety precautions are needed for Préparation de l'Acétaminophène (Paracétamol)?
Key safety precautions include: Acetic anhydride is corrosive and has a strong odor; p-Aminophenol can cause skin irritation; Do not consume the product.
What materials are needed for Préparation de l'Acétaminophène (Paracétamol)?
The main materials required are: p-Aminophenol, Acetic anhydride, Distilled water, Acetone.
What results should I expect from Préparation de l'Acétaminophène (Paracétamol)?
White crystalline solid with melting point 167-170°C. Typical yield is 70-85%. The product should be pure white; discoloration indicates impurities from p-aminophenol oxidation.