Ekstraksi Kafein dari Teh

Mengisolasi alkaloid alami menggunakan ekstraksi cair-cair

Organic Synthesis Advanced (University) 90 menit ~$15,00

Tujuan

Ekstrak kafein dari daun teh menggunakan ekstraksi cair-cair dengan diklorometana, mendemonstrasikan ekstraksi pelarut dan isolasi produk alami.

Latar Belakang

Tea contains 2-4% caffeine by dry weight. After brewing a concentrated tea, caffeine is extracted into dichloromethane (DCM), which is immiscible with water. Sodium carbonate is added to convert tannins to sodium salts, keeping them in the aqueous layer while caffeine partitions into DCM.

Peringatan Keselamatan

  • DCM is a volatile organic solvent — work in fume hood
  • DCM is denser than water (lower layer in separating funnel)
  • Avoid inhaling DCM vapors
  • Do not use open flames near DCM

APD yang Diperlukan

goggles gloves lab_coat

Bahan

  • Tea bags (black tea) (4 bags)
    Strong black tea
  • Dichloromethane (DCM) (60 mL)
    Extraction solvent
  • Sodium carbonate (Na₂CO₃) (5 g)
    To deprotonate tannins
  • Anhydrous sodium sulfate (5 g)
    Drying agent
  • Hot water (200 mL)
    Freshly boiled

Peralatan

250 mL beaker Separating funnel Ring stand Evaporating dish Hot plate Buchner funnel

Prosedur

1

Brew a strong tea by steeping 4 tea bags in 200 mL of hot water for 10 minutes. Squeeze out the bags and allow to cool.

15 menit
2

Add 5 g Na₂CO₃ to the tea. Stir until dissolved.

3 menit
3

Transfer the tea to the separating funnel. Add 20 mL DCM. Shake gently with frequent venting.

5 menit DCM pressure — vent often
4

Allow the layers to separate. Drain the lower DCM layer into a clean flask.

3 menit DCM is the lower layer
5

Repeat the DCM extraction two more times with fresh 20 mL portions. Combine all DCM extracts.

10 menit
6

Dry the combined DCM extracts over anhydrous Na₂SO₄ for 10 minutes. Filter.

12 menit
7

Carefully evaporate the DCM in a fume hood using a warm water bath (not a hot plate directly). White caffeine crystals should remain.

15 menit Fume hood essential — DCM vapors
8

Weigh the crude caffeine. Calculate the yield per gram of tea.

5 menit

Hasil yang Diharapkan

White to off-white crystalline caffeine, typically 20-50 mg from 4 tea bags. The crystals should have a bitter taste. If a melting point apparatus is available, pure caffeine melts at 235-238°C.

Pembersihan

Evaporate remaining DCM in fume hood before disposing of waste. Rinse glassware with acetone then water. Dispose of DCM waste in halogenated solvent container.

Detail

Kategori
Organic Synthesis
Tingkat Kesulitan
Advanced (University)
Durasi
90 menit
Perkiraan Biaya
$15,00
Langkah
8
Bahan
5

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Frequently Asked Questions

What is the objective of Ekstraksi Kafein dari Teh?
Ekstrak kafein dari daun teh menggunakan ekstraksi cair-cair dengan diklorometana, mendemonstrasikan ekstraksi pelarut dan isolasi produk alami.
How difficult is Ekstraksi Kafein dari Teh?
This experiment is rated as Advanced (University). It takes approximately 90 minutes to complete.
What safety precautions are needed for Ekstraksi Kafein dari Teh?
Key safety precautions include: DCM is a volatile organic solvent — work in fume hood; DCM is denser than water (lower layer in separating funnel); Avoid inhaling DCM vapors.
What materials are needed for Ekstraksi Kafein dari Teh?
The main materials required are: Tea bags (black tea), Dichloromethane (DCM), Sodium carbonate (Na₂CO₃), Anhydrous sodium sulfate, Hot water.
What results should I expect from Ekstraksi Kafein dari Teh?
White to off-white crystalline caffeine, typically 20-50 mg from 4 tea bags. The crystals should have a bitter taste. If a melting point apparatus is available, pure caffeine melts at 235-238°C.