135
6
dissolves sufficiently in the aqueous phase.
Due to its lower polarity, this sucrose telomer
changes directly into the non-polar phase and
is therefore no longer available for a consecutive reaction with further butadiene to form
the corresponding diether. In this in situ
extraction process, the product and catalyst
are automatically separated. Thus, the catalyst
can be easily recycled back into the reactor.
In homogeneous phase, mixtures of multiple
ethers are formed again. However, if this reaction is carried out continuously in a liquid/
liquid two-phase system with a polar, aqueous
sucrose solution and a non-polar butadiene
phase, the corresponding monoethers can be
selectively obtained. The palladium catalyst
is dissolved in the aqueous phase. Initially,
the monoether is formed since butadiene
O
O
OH
HO
OH
OH
Sucrose
OH
O
OH
OH
OH
+
HO
O
Fatty acid
n
[OH - ]
O
O
OH
HO
O
OH
OH
O
OH
OH
OH
O
O
O
HO
O
OH
OH
O
OH
OH
OH
O
O
O
HO
OH
OH
O
OH
O
OH
O
O
O
O
O
O
8
Sucrose fatty acid-monoester
O
-diester
-triester
. Fig. 6.22 Esterification of sucrose with fatty acids to ester mixtures (examples)
O
O
OH
HO
OH
OH
OH
O
OH
OH
OH
+
2
[Pd]
O
O
OH
HO
OH
OH
OH
O
OH
OH
O
. Fig. 6.23 Telomerization of sucrose with butadiene to the corresponding monoether
6.3 · Disaccharides