Aldolkondensation (Dibenzalaceton)

Synthese einer UV-absorbierenden Verbindung für Sonnenschutzmittel

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

Ziel

Dibenzalaceton durch eine gekreuzte Aldolkondensation von Benzaldehyd und Aceton synthetisieren und dabei die Bildung von Kohlenstoff-Kohlenstoff-Bindungen demonstrieren.

Hintergrund

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.

Sicherheitswarnungen

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

Erforderliche PSA

goggles gloves lab_coat

Materialien

  • 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

Ausrüstung

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

Durchführung

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.

Erwartete Ergebnisse

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.

Aufräumen

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

Details

Kategorie
Organic Synthesis
Schwierigkeit
Advanced (University)
Dauer
75 Min.
Geschätzte Kosten
$18,00
Schritte
8
Materialien
5

Weitere Experimente

Biodieselherstellung aus Pflanzenöl 60 min Extraktion von Koffein aus Tee 90 min Fischer-Veresterung von Ethylacetat 90 min Herstellung von Acetaminophen (Paracetamol) 80 min Herstellung von Nylon 6,10 (Nylon-Seil-Trick) 30 min Schleimsynthese (vernetztes PVA) 20 min Seifenherstellung durch Verseifung 60 min Synthese von Aspirin (Acetylsalicylsäure) 90 min Synthese von Bananenaroma (Isoamylacetat) 90 min Synthese von Luminol 120 min

Frequently Asked Questions

What is the objective of Aldolkondensation (Dibenzalaceton)?
Dibenzalaceton durch eine gekreuzte Aldolkondensation von Benzaldehyd und Aceton synthetisieren und dabei die Bildung von Kohlenstoff-Kohlenstoff-Bindungen demonstrieren.
How difficult is Aldolkondensation (Dibenzalaceton)?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for Aldolkondensation (Dibenzalaceton)?
Key safety precautions include: NaOH is corrosive; Benzaldehyde is an irritant with a strong almond odor; Acetone is flammable.
What materials are needed for Aldolkondensation (Dibenzalaceton)?
The main materials required are: Benzaldehyde, Acetone, Sodium hydroxide (NaOH), Ethanol, Distilled water.
What results should I expect from Aldolkondensation (Dibenzalaceton)?
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.