Extraction and Separation of Natural Products - Natural Products Chemistry: Sources, Separations, and Structures - page 19

FIGURE 2.7

Coffee berries from Coffea arabica . (Courtesy of Steven Foster.)

O

N

N

N

O N

FIGURE 2.8 The chemical structure of caffeine.

There are three main ways to remove caffeine from coffee:

Extraction Procedure I : Solvent extraction using dichloromethane (DCM).
First, ground coffee in aqueous sodium carbonate is refluxed for 20 min-
utes; the mixture is filtered and cooled. The aqueous filtrate is partitioned
into DCM and this process can be repeated several times to extract more
caffeine . The addition of sodium carbonate converts the protonated form of
the caffeine, which is naturally present in coffee, to its free caffeine form
and this reaction is outlined in Figure 2.9.