The selective epoxidation of olefinic alcohols with t-BuOOH in the presence of vanadium catalysts proceeds in liquid carbon dioxide with high conversions and selectivities. Rates measured in liquid CO2 for the oxovanadium(V) triisopropoxide catalyzed epoxidation of allylic and homoallylic alcohols using tert-butyl hydroperoxide are comparable to those measured in methylene chloride, toluene, and n-hexane. The reactivity of the vanadium(IV) bis(acetylacetonato) oxide catalyst in liquid CO2 was found to be substantially lower than in organic solvents, presumably due to its low solubility in C02. Highly fluorinated acac-type ligands increased the catalytic reactivity of VO(acac)2-catalyzed epoxidations by enhancing catalyst precursor solubility. Heterogeneous epoxidation reactions were also carried out in liquid CO2 using vanadium complexes supported on cation-exchange polymers.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry