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Figure 16.18
(a) Apparent concentrations of palladium are different from actual
concentrations when samples are too concentrated. In this experiment,
all operations were conducted at room temperature with palladium:API
mimic ratios of 1 : 100 000 w/w (i.e., 10 ppm palladium in API mimic).
(b) Phosphate ions accelerate the deallylation of APE in a concentration-
dependent manner. (c) The concentrations of TFP strongly influence
the rates for the deallylation of APE at various temperatures.
Adapted from Ref.
66
.
method performs best when the concentration of palladium-contaminated
API is below 2 mg mL
1
to promote the dissociation of palladium from
the API.
Pd(0/II)
รพ
API
"
Pd(0/II)
API
(16.1)
Interestingly, the rate of the palladium-catalyzed deallylation of APE
is linearly correlated with the concentration of phosphate ions
[Figure 16.18(b)]. The reaction rate was not influenced by Na
2
SO
4
or LiClO
4
concentrations in the range 0.05-50 mM or by Tris buffer (pH 7) in the range
0.1-1 M salt concentration, excluding the possibility for ionic strength-
accelerated kinetics. Because the 1.23 M phosphate pH 7 buffer is
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