Condensation Aldolique (Dibenzalacétone)

Synthèse d'un composé absorbant UV utilisé dans les crèmes solaires

Organic Synthesis Advanced (University) 75 min ~$18,00

Objectif

Synthétiser la dibenzalacétone par condensation aldolique croisée entre le benzaldéhyde et l'acétone, démontrant la formation de liaisons carbone-carbone.

Contexte

The aldol condensation is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Dibenzalacetone is formed by the double aldol condensation of benzaldehyde with acetone under basic conditions. The bright yellow product absorbs UV light and was once used in sunscreen formulations.

Avertissements de sécurité

  • NaOH is corrosive
  • Benzaldehyde is an irritant with a strong almond odor
  • Acetone is flammable
  • Work in a fume hood

EPI requis

goggles gloves lab_coat

Matériaux

  • Benzaldehyde (5 mL)
    Fresh, not oxidized
  • Acetone (1.5 mL)
  • Sodium hydroxide (NaOH) (25 mL)
    10% solution
  • Ethanol (20 mL)
    95%
  • Distilled water (100 mL)
    Ice-cold

Équipement

250 mL Erlenmeyer flask Buchner funnel Filter flask Vacuum pump Melting point apparatus Ice bath Magnetic stirrer

Procédure

1

Dissolve 5 mL benzaldehyde in 20 mL ethanol in the Erlenmeyer flask.

3 min Fume hood — benzaldehyde is an irritant
2

Add 1.5 mL acetone to the flask and stir.

2 min
3

Slowly add 25 mL of 10% NaOH while stirring. A yellow precipitate should begin forming.

5 min NaOH is corrosive
4

Stir the mixture at room temperature for 30 minutes.

30 min
5

Cool the flask in an ice bath for 10 minutes to maximize crystallization.

10 min
6

Collect the yellow crystals by vacuum filtration. Wash with cold water.

10 min
7

Dry the product and determine the melting point (pure dibenzalacetone: 110-112°C).

10 min
8

Calculate the percent yield.

5 min

Résultats attendus

Bright yellow crystals with a melting point of 109-112°C. Typical yield is 60-80%. The product absorbs UV light strongly, which can be confirmed if a UV lamp is available.

Nettoyage

Dispose of organic waste in designated containers. Neutralize NaOH waste. Rinse all glassware.

Détails

Catégorie
Organic Synthesis
Difficulté
Advanced (University)
Durée
75 min
Coût estimé
$18,00
Étapes
8
Matériaux
5

Plus d'expériences

Estérification de Fischer de l'Acétate d'Éthyle 90 min Extraction de la Caféine du Thé 90 min Fabrication de Nylon 6,10 (Tour du Fil de Nylon) 30 min Fabrication de Savon par Saponification 60 min Préparation de l'Acétaminophène (Paracétamol) 80 min Production de Biodiesel à partir d'Huile Végétale 60 min Synthèse de l'Aspirine (Acide Acétylsalicylique) 90 min Synthèse de l'Huile de Banane (Acétate d'Isoamyle) 90 min Synthèse de Slime (PVA Réticulé) 20 min Synthèse du Luminol 120 min

Frequently Asked Questions

What is the objective of Condensation Aldolique (Dibenzalacétone)?
Synthétiser la dibenzalacétone par condensation aldolique croisée entre le benzaldéhyde et l'acétone, démontrant la formation de liaisons carbone-carbone.
How difficult is Condensation Aldolique (Dibenzalacétone)?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for Condensation Aldolique (Dibenzalacétone)?
Key safety precautions include: NaOH is corrosive; Benzaldehyde is an irritant with a strong almond odor; Acetone is flammable.
What materials are needed for Condensation Aldolique (Dibenzalacétone)?
The main materials required are: Benzaldehyde, Acetone, Sodium hydroxide (NaOH), Ethanol, Distilled water.
What results should I expect from Condensation Aldolique (Dibenzalacétone)?
Bright yellow crystals with a melting point of 109-112°C. Typical yield is 60-80%. The product absorbs UV light strongly, which can be confirmed if a UV lamp is available.