Extraction

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EXPERIMENT 2:
EXTRACTION
CHEM200 LABORATORY

EXTRACTION
• A process that involves the transfer of material from one
vehicle to another

• The amount of material that will be transferred depends on
its relative affinity in the two vehicles.

PURPOSE
• Used to isolate a substance from a solid mixture and this is
usually applied in the isolation of compounds from natural
resources.

• The separation of a dissolved substance from a solution
• Removal of soluble impurities from mixtures
• Removal of undesired by-products of a reaction.

O
O

ALKALOIDS

• N-containing heterocyclic
compounds

• Very weakly polar/Hydrophobic
• Favors solubility in non-polar
solvent

O
N

• Organic bases containing
nitrogen, characterized by
their bitter taste.

O

cocaine

O
N
O

N
N

N

caffeine
N
N
nicotine

METHYLXANTHINES
O
HN
O

HN

N
N

O

O

N

O
N

N

xanthine

N
O

NH
N

N

theophylline

N

N

theobromine
O

N
O

N

caffeine

N

TEA (CAMELLA SINENSIS)
Cellulose
structural
carbohydrate

Flavonoid
Polyheterocyclic
compounds w/c
gives tea its color

Tannins
watersoluble
polyphenolic
s

Chlorophyll
green pigment

ALKALO
ID

CAFFEINE CONTENT
Drink
Coffee
Coffee, decaf
Tea
Cocoa
Milk chocolate
Coca-cola
Starbucks (grande)
Red bull (8.4 fl. oz.)
Monster (16 fl. oz)

Caffeine content (mg)
80-125 per cup
2-4 per cup
30-75 per cup
5-40 per cup
6 per ounce
46 per 12 ounces
330
80
160

Tea leaves
treated with
base

Aqueous
solution –
added with
DCM

Aqueous
solution

Residue
(cellulose)

Organic layer
(caffeine,
chlorophyll)

Organic layer
dehydrated
by NaSO4

SOLUBILITY COEFFICIENT
•K D (solubility coefficient) – ratio of solute in the two solvent

Caffeine was extracted from 10.0 grams of tea leaves
(containing 0.5% caffeine) by solid-liquid extraction using
100.0 ml of water and liquid-liquid extraction using DCM.
Initial tests on the solubility of the caffeine on the two solvents
require 2.5 ml of DCM and 20.0 ml of distilled water to
completely solubilize 100.0 mg of caffeine.

1.
2.

Compute for KD

3.

How much caffeine can be extracted by two successive
extraction using 30.0 ml of DCM per extraction procedure?

How much caffeine can be extracted by single extraction
using 60.0 ml of DCM?

FORMULA FOR MULTIPLE
EXTRACTION
• 
Xi = amount left in aqueous layer
X0 = original amount in aqueous layer
Vaq = volume of aqueous layer
Vorg = volume of organic layer
i = number of extractions

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