Ozonides reactivity

The dipolar ion can react in several ways according to the solvent and the stmcture of the olefin. In inert solvents, if the carbonyl compound is highly reactive (eg, an aldehyde), the dipolar ion can be added to the carbonyl fragment to give the normal ozonide or 1,2,4-trioxolane (7) for example, 1,1-and 1,2-dialkylethylenes react in this manner. Tri- or tetraalkyl-substituted olefins produce a smaH, if any, yield of an ozonide when the ozonolysis is... 

Few kinetic studies of the decompositions of higher oxides have been reported one probable reason is that the preparation of pure samples of these highly reactive compounds is difficult. Accordingly, interest has been largely restricted to the most readily available substances which are the alkali and alkaline earth peroxides (02-), superoxides (02) and ozonides (03). Some of these may be hydrated. E values reported [656] for the dehydrations of M02 8 H20 (288—313 K) were 96, 163 and 63 kJ mole-1 for the Ca, Sr and Ba compounds, respectively. 

Langeland and Werstuik <2003CJC525> used ab initio and AIM (atoms-in-molecules) methods to study the structures and reactivity of various phosphate ozonides. Activation energies of the bicyclic complexes (4-ethyl-l-phospha-2,6,7-trioxabicyclo[2.2.2]octane ozonide, l-phospha-2,6,7-trioxabicyclo[2.2.2]octane ozonide, and 1-phos-pha-2,8,9-trioxadamantane ozonide) were found to be significantly higher than the monocyclic structures studied. 

The rearrangement is thought to go through dissociation of the initial ozonide into reactive fragments that recombine to give the ozonide. 

There are many ways to categorize the oxidation of double bonds as they undergo a myriad of oxidative transformations leading to many product types including epoxides, ketones, diols, endoperoxides, ozonides, allylic alcohols and many others. Rather than review the oxidation of dienes by substrate type or product obtained, we have chosen to classify the oxidation reactions of dienes and polyenes by the oxidation reagent or system used, since each have a common reactivity profile. Thus, similar reactions with each specific oxidant can be carried out on a variety of substrates and can be easily compared. 

Reactions of 07 with Alkanes and Alkenes. Ozonide ions are intermediate in reactivity between 0 and 01 (20,21). On MgO they re-... 

The reaction gave only the rearrangement products 333 and 334, and the side product 335, as expected from the reactivity of alkylidenecyclopropane derivatives (Scheme 49). Compound 333 might arise from the 0-0 bond cleavage followed by the rearrangement of a cyclopropyloxy cation to an oxoethyl cation (Scheme 49, path a). Spiro-hexanone 334 could arise from a different fragmentation of ozonide C-O bond and further cyclopropyloxy-cyclobutanone rearrangement (Scheme 49, path b). Oxirane 335 can eventually derive from the same path b or from other side processes [13b]. 

Risk labels, lATA/ICAO, 751-3 Risk phrases, 621, 748, 749 River water, peroxide determination, 642 RNA, ozone disinfection, 616 ROS see Reactive oxygen species Rose Bengal sensitized photooxidation, 890 Rotational barriers, regioselective allylic hydroperoxide formation, 836, 847-9 Rotational isomers, peroxynitrous add, 8-9 Rotational spectra, ozonides, 721, 722-3 RP-HPLC, hydrogen peroxide determination, 627... 

Reaction with aji-unsaturated ketones and lactonesThe reactivity of a,/ -enones to singlet oxygen depends on the conformation. Systems that exist in s-trans-conformations (e.g., A4-3-ketosteroids) react slowly if at all. However, s-cis-enones react readily. For example, (R)-( + )-pulegone (1) reacts to give the products 2-4. The same products are obtained by oxidation with triphenyl phosphite ozonide (3, 324 325). 

The highly reactive carbonyl oxide could be trapped by added carbonyl com-pounds to form normal ozonides. Isolation of dimeric (77) and polymeric... 

Aldehydes tend to be more reactive toward carbonyl oxide than ketones in the recombination reaction (Scheme 9.14, step 3). As a result, tetrasubstituted alkenes generally fail to give normal ozonides604 but rather, 75 undergoes the side reactions indicated above. A new method of ozonation carried out with alkenes adsorbed on polyethylene, however, could yield ozonides of tetrasubsituted alkenes, and even diozonides of dienes could be isolated.605... 

The reactivity of ozone reflects two modes of oxidation non-selective free radical reactions involving hydroxyl radical, and the selective addition of ozone to form an ozonide intermediate and eventually various carbonyls and carboxylic adds (46). The latter sequence, known as ozonolysis, is shown below for anthracene. 

A review of the recent synthetic progress on ozonides at the Karlsruhe University has appeared <1997MI145>. Two older reviews on the structure of the reactive intermediates 1-3 involved in these reactions deserve to be mentioned Carbonyl oxides zwitterions or diradicals <1990AGE344> and Preparation, properties, and reactions of carbonyl oxides < 1991CRV335>. Reviews on cyclic peroxides < 1995COS225> and dioxiranes < 1989CRV1187> are also relevant. 

As it is well known, acyloxy, alkoxy, or phenoxy groups connected to sp2-hybridized carbon atoms in alkenes or aromatics are unreactive to nucleophilic substitution. However, after alkene ozonolysis such groups become attached to sp3-hybridized carbon atoms and become reactive. It was shown <1989TL1511> that such substitutions have to be carried out at 40 °C when they compete with thermolytic reactions of the ozonides, lowering the yields. However, if 2,3-dichloropropene and as- or /ra/rt-1,2,4-trichloro-2-butene are ozonized, one obtains stable ozonides 68a-70... 

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