Epoxidation by hydrogen peroxide

Olefin epoxidation by hydrogen peroxide catalysed by MTO on niobia in the presence of urea was successfully applied with better results than under homogeneous conditions, thereby transforming simple olefin substrates to unsaturated fatty acids and esters [56,57]. 

Other c,/3-unsaturated nitriles (Eq. 68) converted into the corresponding epoxides by hydrogen peroxide oxidation under controlled pH include a-phenykiimamomtrile, a-oyano-/3-methylcrotorKH)itril and ethyl a-cyano- -methylcrotonftte.mj-1817... 

Sometimes, due to special conditions, chain transformation may hardly be induced. An example of this is the reaction of propylene epoxidation. However, intense generation of active sites (H02) in the primary reaction gives the possibility of suppressing acceptor chain transformation to undesired products and simultaneously stimulating the main direction—epoxidation. This is obtained due to chemical induction, which induces and speeds up selective transformation of propylene (acceptor) to a quite high rate. The authors have implemented such a conjugation mechanism in propylene epoxidation by hydrogen peroxide [10]. 

Methyltrioxorhenium (MTO) catalyses direct epoxidation by hydrogen peroxide. The reaction is carried out in pyridine, avoiding acidic conditions detrimental to high epoxide yield and uses less concentrated hydrogen peroxide (30%) than other methods (58). This method epoxidized soybean and metathesized (see Section 7.4)... 

M. Fujita, L. Que Jr., In situ formation of peracetic acid in iron-catalyzed epoxidations by hydrogen peroxide in the presence of acetic acid, Adv. Synth. Catal. 346 (2004) 190. 

D. Tantanak, M. A. Vincent, 1. H., Hillier, Elucidation of the mechanism of alkene epoxidation by hydrogen peroxide catalyzed by titanosilicates A computational study, Chem. Commun. (1998) 1031. 

N. A. Stephenson, A. T. BeU, Influence of solvent composition on the kinetics of cyclooctene epoxidation by hydrogen peroxide catalyzed by iron(III) [tetrakis(pentafluorophenyl)] porphyrin chloride (I., TPP)I < 1. Inorg. Chem. 45 (2006) 2758. 

Electrondeficient olefins can be epoxidized by hydrogen peroxide in the presence of bases. This method, known as the Weitz-Scheffer reaction, is used especially for the epoxidation of o,p-unsaturated ketones. Wynberg et al. [4] epoxidized a series of such ketones with hydrogen peroxide in the presence of quaternary ammonium salts of optically active alkaloids. Especially when phase-transfer conditions were used they yielded an e.e. of about 50% (Scheme 3). 

Yin, G. Buchalova, M. Danby, A. M. Perkins, C. M. Kitko, D. Carter,J. D. Scheper,W. M. Busch, D. H. Olefin epoxidation by hydrogen peroxide adduct of a novel non-heme manganese(IV) complex demonstration of oxygen transfer hy multiple mechanisms. 

T. Yamase, E. Ishikawa, and Y. Asai, Alkene epoxidation by hydrogen peroxide in the presence of... 

Another new group of catalyst systems for direct epoxidations by hydrogen peroxide is the arsonated polystyrenes. Using a triphasic system of CHCI3, 30% H2O2, and the catalyst (in the form of beads), slow but selective epoxidations of... 

It was noted that cross-linked polystyrene-telluric acid (a product of TeCl4 polycondensation with a copolymer of divinylbenzene and styrene and subsequent hydrolysis in an alkaline medium) is an active catalyst of olefin epoxidation by hydrogen peroxide [210]. At 333 K and in dioxane and terf-butanol solutions, the above catalyst quantitatively yielded epoxides from a wide range of unsaturated compounds such as aromatic and aliphatic hydrocarbons, alcohols and their derivatives. A plausible mechanism for the catalytic properties of a tellurium compound during polycondensation was discussed. 

Renoud, J.P., P. Battioni, J.E. Bartoli, and D. Mansuy (1985). A very efficient system for alkene epoxidation by hydrogen peroxide catalysis by manganese-porphyrins in the presence of imidazole. J. Chem. Soc., Chem. Common. 13, 888-889. 

A review has illustrated the importance of atomic-level DFT studies in elucidation of the function of hydrogen bonds in organocatalytic reactions through influence on the mechanism of substrate activation and orientation, and the stabilization of transition states and intermediates. Examples discussed include stereoselective catalysis by bifunctional thioureas, solvent catalysis by fluorinated alcohols in epoxidation by hydrogen peroxide, and intra-molecular cooperative hydrogen bonding in trans-a,a -(dimethyl-l,3-dioxolane-4,5-diyl)bis(diphenyl methanol) (TADDOL) (7)-type catalysts. ... 

Yamase, T, Ishikawa, E., Asai, Y, et al. (1996). Alkene Epoxidation by Hydrogen Peroxide in the Presence of Titanium-Substituted Keggin-Type Polyoxotungstates [PTi tWi2-x... 

Stephenson NA, Bell AT (2007) Mechanistic study of iron(Ill) [tetralds(pentafluorophenyl) porphyrin triflate (F20TPP)Fe(OTf) catalyzed cyclooctene epoxidation by hydrogen peroxide. Inoig Chem 46(6) 2278-2285... 

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