Ozonides secondary

Secondary ozonide Secondary plasticizer Secondary recycling Secondary structures Secosteroid... 

Organic peroxides can be classified according to peroxide stmcture. There are seven principal classes hydroperoxides dialkyl peroxides a-oxygen substitued alkyl hydroperoxides and dialkyl peroxides primary and secondary ozonides peroxyacids diacyl peroxides (acyl and organosulfonyl peroxides) and alkyl peroxyesters (peroxycarboxylates, peroxysulfonates, and peroxyphosphates). 

Unsaturated compounds undergo ozonization to initially produce highly unstable primary ozonides (15), ie, 1,2,3-trioxolanes, also known as molozonides, which rapidly spHt into carbonyl compounds (aldehydes and ketones) and 1,3-zwitterion (16) intermediates. The carbonyl compound-zwitterion pair then recombines to produce a thermally stable secondary ozonide (17), also known as a 1,2,4-trioxolane (44,64,125,161,162). 

Ozonolysis of styrene and ethylidenecyclohexane in the presence of [ 0]benzal-dehyde yields stable secondary ozonides incorporating 0. O NMR showed that labelled oxygen appeared as the ether oxygen, not the peroxo bridge, thus confirming the Criegee mechanism as opposed to the so-called unified concept. ... 

Ozonolysis of alkenes in participating solvents such as alcohols often leads to trapping of intermediates. Most commonly, an alcohol will react with the carbonyl oxide zwitterion, generated from cycloreversion of the primary ozonide (Section 4.16.8.2), to give an alkoxy hydroperoxide. The secondary ozonide (1,2,4-trioxolane) is usually more stable to nucleophilic attack from alcohols. 

The most commonly employed transformations for the construction of five-membered rings containing three sulfur or oxygen atoms in the 1,2,4-positions are shown in Table 11. These have attracted more interest than the syntheses from acyclic components. The rearrangement of a 1,2,3-trioxolane (primary ozonide) to a 1,2,4-trioxolane (secondary ozonide) is the most generally applicable method for preparation of this ring system and will be discussed further in Sections... 

FIGURE 2. (a) Room-temperature O NMR spectrum of the secondary ozonide of styrene obtained after ozonolysis in pentane at —78 °C. (b) Room-temperature O NMR spectrum of the secondary ozonide of styrene obtained after ozonolysis in pentane at —78°C in the presence of 1.0 equiv. of O-labeUed benzaldehyde. Reproduced by permission of Wiley-VCH Verlag GmbH from Reference 15... 

Temperature-programmed thermal desorption particle beam MS of collected secondary aerosol particles shows that the major ozonization products of normal alkenes in an environmental chamber include organic hydroperoxides, peroxides, final ozonides and monocarboxylic acids. Attempts to analyze these compounds by GC result in their decomposition to simpler molecules". 

This is an additive constitutive property that is easy to determine experimentally and has theoretical significance, but it has been superceded by spectral methods that offer a deeper insight into the molecular structure. Nevertheless, it has historical value in the early elucidation of the structure of secondary ozonides as substituted 1,2,4-trioxolanes . ... 

Secondary ozonides see Final ozonides Selected reaction monitoring (SRM), mass spectrometry, 693 Selenides... 

Diaryl- and tetraaryl-substituted furans such as tetraphenylfuran (384) for example, yield generally cw-diaroylethylenes such as 380, probably via intermediate ozonide formation.257 Secondary reactions seem to depend very much on the nature of the solvents. Thus, cis-dibenzoylstilbene (380) has been observed by direct photooxygenation of 384 in CS2 as well as by methylene blue-sensitized photooxygenation of 384 in methanol.257,258 However, when the latter reaction was carried out in acetone, epoxide 386 and the enolbenzoate 387 were obtained.258... 

In any event, in the solvent cage in which they are formed in the liquid phase, or for higher molecular weight alkenes condensed on surfaces, the two fragments formed by decomposition of the primary ozonide are held in close proximity and recombine to form a secondary ozonide ... 

Fajgar, R J. Vitek, Y. Haas, and J. Pola, Observations of Secondary 2-Butene Ozonide in the Ozonation of Trans-2-butene in the Gas Phase, Tetrahedron Lett., 37, 3391-3394 (1996). 

Martinez and Herron (1981, 1983) proposed that the adduct has a cyclic structure, similar to organic secondary ozonides ... 

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