Epoxidation with organic peracids

The rates of metal-catalyzed epoxidations are also influenced by the structure of the olefin and the structure of the hydroperoxide. The relative rates of epoxidation of a series of olefins using a mixture of r-Bu02H and Mo(CO)6 paralleled quite closely those for epoxidations with organic peracids.435... 

Direct Oxidation with Stoichiometric Oxidants. Discovered by Prilezhaev in 1909,211 the typical epoxidation reaction of alkenes is their oxidation with organic peracids. Of the large number of different peroxycarboxylic acids used in... 

D. Swern, Epoxidation and Hydroxylation of Ethylenic Compounds with Organic Peracids, Org. React. 1953, 7, 378 133. 

All of the reactions just described closely parallel the reactions of the same substrates with organic peracids. They probably involve rate-determining oxygen transfer from a metal-hydroperoxide complex to the substrate via a cyclic transition state, described earlier for the epoxidation of olefins with these reagents433,435... 

The most widely accepted method for epoxidation of alkenes remains oxidation with organic peracids. The early work (up to 1970) in this field shows that a large number of dienes and polyenes were oxidized in this manner . The most commonly used peracids are peracetic, monoperphthalic and perbenzoic acids which are most dominant in industrial applications. On the other hand, in laboratory procedures m-chloroperbenzoic acid, MCPBA, is often used, with trifluoroperacetic acid cited in more difficult transformations. Recently, the transportation of m-chloroperbenzoic acid has been restricted and the use of other peroxygen agents has been gaining acceptance as a general alternative. Among the substrate types epoxidized it would be especially worthy to point out polyunsaturated... 

Swern, D. Epoxidation and hydroxyiation of ethyienic compounds with organic peracids. Org. React. 1953, Vii, 378 33. 

Epoxides are usually prepared in the laboratory by the reaction of olefins with organic peracids or by the reaction of halohydrins with alkali. The mechanism of the first of these processes has not been completely elucidated,170 but the second involves an ionic reaction whose mechanism has already been discussed (p. 96). The synthesis of phenyl-methyl glycidic ester176 appears to proceed by a related sequence ... 

Cyclic ethers used as fragrances include a number of terpenoid compounds. Some of them, such as 1,4-cineole [470-67-7] and 1,8-cineole, occur in essential oils in significant quantities. Others are only minor components examples are rose oxide, ner-ol oxide [1786-08-9], and rose furan [15186-51-3], which contribute to the specific fragrance of rose oil. Caryophyllene oxide [1139-30-6], which has a woody, slightly ambergris-like odor, can be prepared by treatment of -caryophyllene with organic peracids. a-Cedrene oxide [11000-57-0] is another wood-fragrance compound, which can be easily prepared by epoxidation of cedarwood oil hydrocarbons. 

Cycloolefins (COLs) with unsaturated substituents are used as starting materials for the synthesis of ACECs. The epoxidation of COLs and of the COL unsaturation in particular with organic peracids (PAs) is the most important step of the synthesis. 

Epoxidation is carried out by four different procedures (i) epoxidation with peracids such as peracetic acid or perbenzoic acid in the presence of an acid catalyst (ii) epoxidation with organic and inorganic peroxides, including transition metal catalysts (iii) epoxidation with halohydrins using hypoha-lous acids and their salts and (iv) epoxidation with molecular oxygen. 

For the lability of alkoxy-type radicals, see Ando, W. (ed.). (1992). Organic Peroxides. Wiley, New York. In the same way, olefin epoxidation with peracids can be simply viewed as an electron transfer, followed by mesolytic cleavage of the peracid anion radical to carboxylate and hydroxyl radical, followed by homolytic coupling and proton loss. See also Nugent, W.A., Bertini, F. and Kochi, J.K. (1974). J. Am. Chem. Soc. 96,4945... 

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