| 摘要 |
Compositions of formula (I): Q3XW4O24-2n (I) wherein: Q represents a cation of an "onium" salt; X is either a P or an As atom; while n is 0, 1 or 2. The preparative method consists in reacting an oxygenated tungsten (VI) derivative, an oxygenated P (V) or As (V) derivative, and hydrogen peroxide, in an aqueous acid phase, with an "onium" salt or a precursor thereof, if desired contained in an organic phase immiscible with the aqueous phase, at substantially room temperature. The oxygenated compounds of W (VI), P (V) or As (V) may be prepared "in situ" under the conditions of the reaction. Compositions (I), which appear as solids or as viscous oils, find use as oxidizing agents in general in oxidation processes, and especially as epoxidation catalysts for olefinic compounds, both in a homogeneous phase as well as in a heterogeneous phase, and preferably according to the phase-transfer technique, in the presence of oxidizing agents.
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