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3.2 Extractions


3.2.1 Procedure

3.2.2 Removal of solids

It’s important to remove any solids before partitioning the reaction mixture, as the presence of fine particles can lead to the formation of an emulsion, making separation difficult. 

To remove fine particles:

3.2.3 Partitioning

Partition the product between an organic solvent and water or another aqueous solution such as brine.

Procedure:

Do not dispose of either layer until you are sure that your product has been recovered.

3.2.4 Pick an extraction solvent

Specific gravity is often quoted in place of density:            SG < 1.0 = Float on H2O

SG = Density of solvent / Density of water                         SG > 1.0 = Sink under H2O


Solvent

Specific gravity

Pentane

0.626

Petroleum ether

0.656

Hexane

0.659

Diethyl ether

0.713

Cyclohexane

0.779

Tert-butyl alcohol

0.781

Isopropanol

0.785

Acetonitrile

0.786

Ethanol

0.789

Acetone

0.790

Methanol

0.791

1-Octanol

0.826

Toluene

0.867


Solvent

Specific gravity

Benzene

0.879

Tetrahydrofuran

0.889

Ethyl acetate

0.895

N,N-Dimethylformamide

0.944

Pyridine

0.982

Propanoic acid

0.993

Water

1.000

Acetic acid

1.049

Dimethyl sulfoxide

1.092

Deuterium oxide

1.107

Ethylene glycol

1.115

Propylene carbonate

1.21

Chloroform

1.498



Ether is the most popular because it can be removed easily on the rotary evaporator, ethyl acetate also works well but is harder to remove.

3.2.5 Pick the size of your separatory (sep.) funnel

Usually 125 or 250 mL, large scale reactions (1-10g) require 500 mL or 1 L sizes. Remember that your sep. funnel will contain the solvent and wash liquid which must be thoroughly mixed.

 

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