Biomedical Engineering Reference
In-Depth Information
The water content of reaction medium would be an important factor affecting the
conversion because water is one of the condensation products. The synthesis of
eicosapentaenoyl ascorbate was conducted in acetone having various initial water contents
and at the fixed molar ratio of eicosapentaenoic acid : ascorbic acid = 0.129 mmol:0.125
mmol [25]. The transient changes in the conversion are shown in Figure 4(a). The
condensation proceeded faster at the lower water contents. The apparent maximum
conversion was also higher at the lower water contents as shown in Figure 4(b). The
maximum conversion significantly decreased as the water content increased. This would be
ascribed to the predominance of hydrolysis at higher water content.
We attempted to evaluate
the equilibrium constant for the formation of lauroyl ascorbate through condensation [24].
The equilibrium constant,
K
C
, is defined by
C
C
P
W
K
=
(1)
e
e
C
C
C
A
F
e
e
Figure 4. Effect of initial acetone water content on the synthesis of 6-
O
-eicosapentaenoyl ascorbate
through lipase-catalyzed condensation. (a) Transient changes in the conversion at various water
contents shown in the figure. The amounts of eicosapentaenoic acid and ascorbic acid added to 2.5 ml
acetone were 0.129 mmol and 0.125 mmol, respectively. (b) Dependence of the apparent maximum
conversion on the initial water content. The curves were empirically drawn.
