Catalysts for selective aerobic oxidation under ambient conditions - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 255

16. HETEROGENEOUS SYSTEMS
Since it was found that the reaction proceeds faster, with no induction
period and is less self-inhibited in trifluoroethanol, the next logical step was
to replace trifluoroethanol with high molecular weight perfluorinated
polyethers (PFPEs). The PFPEs are the principal components of TSPs and
are effectively nontoxic. The systems appears to be
active for selective aerobic sulfoxidation of CEES in the PFPE oil Galden D-
02 ® , (17 turnovers per hour, see Table 1 in a recent article) 23 and highly
active in Fomblin MF-300 ® ,a PFPE surfactant with terminal carboxylic acid
functional groups (1170 turnovers per hour, Figure 7).
However, both these systems are heterogeneous because is
only partially soluble in Fomblin MF-300 ® and completely insoluble in
Galden D-02 ® (perfluorinated oil). In Fomblin MF-300 ® the catalyst
partially dissolves when CEES is added because the Au(III) precursor,
is soluble. With the co-catalyst activity of Cu(II) in acetonitrile
in mind, the sulfate salts of Fe(III), Cu(II), Mn(II), V(IV), Ti(IV), Co(II),
and Ni(II) were also evaluated in Fomblin MF-300 ® . A synergistic effect is
observed when all of these redox active metals are added to the