Discovery and optimization of rapid manganese catalysts for the epoxidation of terminal olefins

Twenty-two MnII complexes were screened for the catalytic epoxidation of terminal olefins using peracetic acid as the oxidant. A limited number of these complexes are efficient catalysts using peracetic acid solutions generated with H2SO4 (PAAC), but most complexes are effective at 1 mol% catalyst loading using peracetic acid generated with strongly acidic resins (PAAR). Under the less acidic conditions of PAAR, [MnII(phen)2(CF3SO3)2] has the highest activity of the catalysts screened, and epoxides terminal olefins using as little as 0.02 mol% catalyst within 5 min. The dimeric species [MnIII,IV2(phen)4(O)2](ClO4)3 is also a viable epoxidation catalyst with PAAR, but the dimeric species is reduced by the residual H2O2 to monomeric MnII species under the reaction conditions. By comparison, a similar dimeric complex [MnIII,IV2(R,R-mcp)2(O)2](ClO4)3, is not reduced by H2O2 under the reaction conditions and is not catalytically active, supportive of the notion that the catalytically relevant species is monomeric.

Twenty-two MnII complexes were screened for the catalytic epoxidation of terminal olefins using peracetic acid as the oxidant. Of these complexes, few are active epoxidation catalysts under strongly acidic conditions, but most can epoxidize 1-octene under less acidic conditions. Of these catalysts [Mn(phen)2(CF3SO3)2] can epoxidize terminal olefins using as little as 0.02 mol% catalyst within 5 min. Figure optionsDownload as PowerPoint slide