Catalysts for selective aerobic oxidation under ambient conditions - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 256

system (see Table 2 in a recent paper). 23 The most active co-catalyst is
Cu(II). When 2 equivalents of is combined with 1 equivalent of
the catalyst is 3.8 and 6.5 times more effective after 10
minutes of reaction time than when one of the components is omitted
and respectively). It is noteworthy that
is catalytically inactive without a feature that is
present in fluorinated media as well as in acetonitrile. Also, the recently
reported data (Figure 6 in a recent paper) 23 indicate that inhibition by
product sulfoxide is less pronounced in the
system.
Importantly, product selectivity in the heterogeneous systems is the same
as in acetonitrile, eq 1 23 , namely that no sulfoxide overoxidation to sulfone is
observed in these systems within the limits of instrumental detection. This is
very important for mustard gas (HD) oxidative detoxification, because the
sulfoxide, “HD(O)”, is significantly less toxic than the sulfone,
Since these systems are heterogeneous, their full kinetic evaluation is not
possible. However, they are very similar to homogeneous ones because the
same product (CEESO) and selectivity (~100% CEESO) are observed; both
halide and are required for activity; and Cu(II) is a highly active co-
catalyst. These similarities suggest that the key features of the mechanisms
in the two types of media are also very similar,
17. EFFECT OF AMINO ACIDS
A key goal of this work is to develop a catalytic system that could be
incorporated into TSPs for the oxidative detoxification of mustard gas.
Cornified layers of skin (epidermal) cells contain different amino acids
which could bind to active Au(III) catalytic complexes and thus could reduce
or eliminate their activity. Therefore, the effect of amino acids containing
such functions as alkyl, amide, amine, carboxylate, imidazole, indole,
alcohol, phenol, disulfide, thioether, and guanidino side chain groups on the
catalytic activity for aerobic CEES oxidation were evaluated in
heterogeneous systems using Fomblin MF-300 ® as a solvent. These Au(III)-
based catalysts remain active in the presence of most amino acids. Only a
few amino acids exhibit moderate inhibition of the reaction. The inhibitory
effect is as follows: tryptophan (indole) (most inhibiting) > methionine
(thioether) > tyrosine (phenol) > leucine (alkane) > histidine (imidazole) >
arginine (guanidine) > asparagine (amide) > serine (alcohol), aspartate
(carboxylate) > cystine (disulfide) (least inhibiting). 23 Thus, if Au(III)
centers in the suspended Au(III)-based catalysts in a deployed TSPs have
direct molecular contact with the amino acids in the skin, then the epidermal