Aerobic epoxidation, nickel complex

Nonstereospecific aerobic epoxidations of alkenes in the presence of aldehydes catalyzed by nickel(II),298 iron(in),299 and cobalt(II)300 complexes, and clay-supported nickel acetylacetonate301,302 have been reported. A radical mechanism has been postulated. The involvement of active copper species and peracids were suggested in a similar reaction catalyzed by copper salts.303... 

Molybdenum catalysts, Ruthenium porphyrins, Ruthenium(lll) complexes, Iron catalysts, Titanium catalysts. Sharpless epoxidation, Tungsten catalysts, Methyltrioxorhenium, Cobalt, Nickel, Platinum, Aerobic epoxidation, Lanthanum, Ytterbium, Calcium, BINOL-complexes. 2008 Elsevier B.v. 

Figure 2. Relationship of oxidation potentials and catalytic activities in aerobic epoxidation catalyzed by nickel(II) complexes and primary alcohol...

Highly Efficient Aerobic Epoxidation Catalyzed by Nickel(II) Complex... 

After screening several reductants in the aerobic epoxidation of olefins catalyzed by nickel(II) complexes, it was found that an aldehyde acts as an excellent reductant when treated under an atmospheric pressure of molecular oxygen at room temperature (Scheme 6). Similar reactions have been reported in the patents. Propylene was monooxygenated into propylene oxide with molecular oxygen in the coexistence of metal complexes and aldehyde such as acetaldehyde " or crotonaldehyde, but the conversion of olefin and the selectivity of epoxide were never reached satisfactory levels. Recently, praseodymium(III) acetate was also shown to be an effective catalyst for the aerobic epoxidation of olefins in the presence of aldehyde. ... 

For the aerobic epoxidation of 1,2-disubstituted olefins, the use of smaller amount of nickel(II) complex was effective to improve yield of the corresponding epoxide (B) Dilution Method). Isovaleraldehyde was found to be remarkably effective for the epoxidation of terminal olefin, and 1,2-epoxy alkane was obtained in good to high yield (C) Isovaleraldehyde Method). 

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