Chemistry Reference
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13. PRODUCT INHIBITION (DMSO EFFECT)
As noted above, the reaction slows down as product CEESO accumulates
(Figure 1). Inhibition by CEESO product has been proven by using DMSO
as a model and also by nonlinear least squares fitting of kinetics of CEES
consumption.
22
However, a more thorough evaluation of the DMSO
dependence reveals that at low DMSO concentrations (< 0.03 M), the initial
reaction rate increases to a maximum and then subsequently decreases with
increasing [DMSO]. A maximum rate is observed at ~10 mM DMSO (Table
2).
A more complex model compared to the one previously described
22
to
interpret this dual effect of DMSO (initial acceleration followed by
inhibition) is given in Scheme 3.
Equilibria for the reaction of DMSO with Au(III) are similar to those of
CEES with Au(III). DMSO forms complexes
7
,
2'
and
2”
. Complex
7
is an
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