In epoxidation of alkenes

Scheme 4.8 Silica-supported l,4-dimethyl-l,4,7-triazacyclononane in epoxidations of alkenes.

Fluorous solvents proved to be highly effective in epoxidation of alkenes. H202 can be used in combination with trifluoroacetone,27 perfluoroacetone,28 or a mixture of perfluoroacetone and hexafluoro-2-propanol.29 In fluorinated alcohols as solvents uncatalyzed epoxidations with aqueous H202 are performed.30,31... 

Cobalt tetraarylporphyrins with fluorine-containing substituents were active in epoxidation of alkenes using fluorous catalysis in the presence of oxygen and 2-methylpropanal [167,170-171]. Manganese and cobalt complexes of perfluorinated tetraazocyclonone catalyzed allylic oxidation of alkenes with r-BuOOH/Oa [172]. The complex with the salen ligand 57 was active in alkene epoxidation under Mikayama s conditions, and indene was epoxidated at a high stereospecificity [173]. 

Very recent literature indicates that Ag clusters of only several tens of atoms, also yield exceptionally high selectivities in epoxidation of alkenes, other than ethane. The preparation of these clusters is currently only possible in very small quantities, and upscaling of the vacuum methodologies is very necessary. Perhaps also atomic layer deposition, recently applied successfully, could provide for a solution, in particular if this becomes feasible in a continuous mode of operation. 

Epoxides are well known as one of the most valuable intermediates to produce commercially important chemicals such as polyglycols, polyamides, polyurethanes and so many other polymers, chiral pharmaceuticals, pesticides, detergents, agrochemicals, food additives, dyestuffs, flavor and fragrance compounds, surfactants, antistatic agents, corrosion protection agents, textiles, non-toxic PVC plasticizers and stabilizers. They are also valuable additives to lubricants and adhesives. In the last decade, several soluble Schiff base complexes of Cr, Mo, Re, Ni, Co, Mn, V, Cu, Ru, and Ti have been employed as active homogenous catalysts in epoxidation of alkenes. 

Upadhyay, M.J. Bhattacharya, P.K. Ganeshpure, P.A. Satish, S. (1994) Synthesis of binuclear amide complexes of Ru(ill) and study of their catalytic activity in epoxidation of alkenes, J. Mol Catal, 287-94. 

---