Page 14 - phytochemistry general program

This method is used to extract the alkaloidal bases from the powered plant. .1
So, the powered plant must be firstly prepared by liberation of the free base .2
.1
by addition of suitable alkali.
The alkalinized power is packed in the extraction apparatus and extracted .1
.2
with the H2O-immiscble organic solvent .3
.4
The water-immiscible organic solvents used for extraction of alk. bases are
CHCl3 (chloroform)
Ether.

Methylene chloride (CH2Cl2),….

Most alks. are dissolved in CHCl3 except 4ry alk, alk. N-oxide and morphine

The choice of alkali depends on :

The degree of basicity of alkaloids. .1
The chemical nature of alkaloidal bases. .2
The nature of the acid in combination with alkaloids. .3

The alkali used for liberation of free bases usually .1
Sodium hydroxide. .2
Calcium hydroxide. .3
.4
Magnesium hydroxide. .5
Sodium Carbonate. .6

Sodium bicarbonate.
and in most cases Ammonia.

NH4OH .1
.2
The alkali of choice in alkalinization, and liberation of free bases, and it is
the most widely used because: .3

It is volatile and easily removed on evaporate
It is suitable for alkalinization of phenolic & ester alkaloids (where we cannot

use NaOH).
It is also suitable for alkalinization of powder that contain traces of fatty

matter (NaOH cause saponification).

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