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Dioxirane Oxidation
Oxidation with dioxiranes refers to the introduction of oxygen into organic substrates using dioxiranes. Dioxiranes are well known for epoxidations (synthesis of epoxides from alkenes). Dioxiranes oxidize other unsaturated functionality, heteroatoms, and alkane C-H bonds. Dioxiranes are metal-free oxidants. Epoxidations Dioxiranes are electrophilic oxidants that react more quickly with electron-rich than electron-poor double bonds; however, both classes of substrates can be epoxidized within a reasonable time frame. The mechanism of epoxidation with dioxiranes likely involves concerted oxygen transfer through a spiro compound, spiro transition state. As oxygen transfer occurs, the plane of the oxirane is perpendicular to and bisects the plane of the alkene pi system. The configuration of the alkene is maintained in the product, ruling out long-lived radical intermediates. In addition, the spiro transition state has been used to explain the selectivity in enantioselective epoxidatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioxirane
In chemistry, dioxirane (systematically named dioxacyclopropane, also known as methylene peroxide or peroxymethane) is an organic compound with formula . The molecule consists of a ring with one methylene and two oxygen atoms. It is of interest as the smallest cyclic organic peroxide, but otherwise it is of little practical value. Synthesis Dioxirane is highly unstable and the majority of studies of it have been computational; it has been detected during the low temperature (–196 °C) reaction of ethylene and ozone, although even at these temperatures such a mixture can be explosive. Its formation is thought to be radical in nature, preceding via a Criegee intermediate. Microwave analysis has indicated C-H, C-O and O-O bond lengths of 1.090, 1.388 and 1.516 Å respectively. The very long and weak O-O bond (cf. hydrogen peroxide O-O = 1.47 Å) is the origin of its instability. Other dioxiranes Beyond the parent dioxirane, which is mainly of theoretical interest, more c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
