羟醛缩合（二苯亚苄基丙酮）

合成用于防晒霜的紫外线吸收化合物

Organic Synthesis Advanced (University) 75 分钟 ~$18.00

目标

通过苯甲醛与丙酮的交叉羟醛缩合反应合成二苯亚苄基丙酮，演示碳碳键的形成。

背景

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.

安全警告

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

所需PPE

goggles gloves lab_coat

材料

  • 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

设备

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

步骤

1

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

3 分钟 Fume hood — benzaldehyde is an irritant
2

Add 1.5 mL acetone to the flask and stir.

2 分钟
3

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

5 分钟 NaOH is corrosive
4

Stir the mixture at room temperature for 30 minutes.

30 分钟
5

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

10 分钟
6

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

10 分钟
7

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

10 分钟
8

Calculate the percent yield.

5 分钟

预期结果

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.

清理

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

详情

类别
Organic Synthesis
难度
Advanced (University)
时长
75 分钟
预估费用
$18.00
步骤数
8
材料
5

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Frequently Asked Questions

What is the objective of 羟醛缩合（二苯亚苄基丙酮）?
通过苯甲醛与丙酮的交叉羟醛缩合反应合成二苯亚苄基丙酮，演示碳碳键的形成。
How difficult is 羟醛缩合（二苯亚苄基丙酮）?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for 羟醛缩合（二苯亚苄基丙酮）?
Key safety precautions include: NaOH is corrosive; Benzaldehyde is an irritant with a strong almond odor; Acetone is flammable.
What materials are needed for 羟醛缩合（二苯亚苄基丙酮）?
The main materials required are: Benzaldehyde, Acetone, Sodium hydroxide (NaOH), Ethanol, Distilled water.
What results should I expect from 羟醛缩合（二苯亚苄基丙酮）?
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.