Ozonide characterization

The ozonides are characterized by the presence of the ozonide ion, O - They are generally produced by the reaction of the inorganic oxide and ozone (qv). Two reviews of ozonide chemistry are available (1,117). Sodium ozonide [12058-54-7] NaO potassium ozonide [12030-89-6] 35 rubidium ozonide [12060-04-7] RbO and cesium ozonide [12053-67-7] CsO, have all been reported (1). Ammonium ozonide [12161 -20-5] NH O, and tetramethylammonium ozonide [78657-29-1/, (CH ) NO, have been prepared at low temperatures (118). 

The bicyclic ozonides 12 23) and thiaozonides 13 2S) afford on catalytic hydrogenation (Pd-C) the expected 1,4-diones 61 (Eq. 47). Alternatively, deoxygenation of 12 or desulfurization of 13 with triphenylphosphine led to the same products essentially quantitatively. Both reductions served for the chemical characterization of these... 

Significant advances in the chemistry of these ring systems over the past 10 years include the first unambiguous detection, and characterization by microwave spectroscopy as 1,2,3-trioxolane, of the primary ozonide from ethene and ozone (cf. Section 4.15.3.2), and the introduction of 1,3,2-dioxathiolane 2,2-dioxides as epoxide equivalents in organic synthesis (cf. Section 4.15.5.3). Advances have also been made in the synthesis and characterization of the chemistry of 1,2,3-trithiolanes and 1,2,3-trithioles. 

O NMR resonances for several 1,2,4-trioxolanes have been reported <91CC816> (Table 6). The ether and peroxide signals are very distinct proving the value of O NMR as an analytical tool for characterization of ozonides. It can be used to determine unequivocally whether a compound is an ozonide (peroxide 6 295-327 ppm) or tetroxane ((26), for example d = 256 ppm). This is often a competing product from the ozonolysis reaction of alkenes (Section 4.16.8.2). 

Several stable triterpenoid natural products containing 1,2,4-trioxolanes have been characterized, for example adian-5-ene ozonide (175) isolated from the fern Adiantum monochlamys <90CPB79,... 

One of the most important features of the ozonolysis reaction of alkenes is one in which ozone adds to the C=C bond to form a primary ozonide (1,2,3-trioxolane). The Criegee mechanism suggests that this unstable intermediate decomposes into a carbonyl compound and a carbonyl oxide that recombine to form a final isomeric ozonide (1,2,4-trioxolane). Direct spectroscopic evidence for a substituted carbonyl oxide has only recently been reported by Sander and coworkers for the NMR characterization of dimesityl carbonyl oxide. Kraka and coworkers have theoretically modeled dimesityl carbonyl oxide and confirmed the structural aspects reported by Sander and coworkers on the basis of NMR data. 

The structural elucidation of the ozonide function is not always an easy task. For example, compounds 282 and 283, carrying stiff substituents on the double bond, each yield on ozonization a stable derivative containing three O atoms, that is hard to characterize as POZ or FOZ by the usual chemical and spectroscopic methods ... 

The ozonides of choline and ethanolamine phosphatides and triglycerides can be subjected to reduction with triphenylphosphine to yield the corresponding core aldehydes, and further derivatized to the 2,4-dinitrophenylhydrazones (DNP). The core aldehydes and their DNP derivatives can be separated by HPLC and characterized by various techniques, including EI-MS and TS-MS of positive and negative ions . See also Section VHI.E. 

IR spectrophotometry, 661, 662 TEARS assay, 667 hydroperoxide oxidation, 692 Upid hydroperoxides, 977-8 decomposition, 669 DNA adducts, 978-84 protein adducts, 984-5 ozone adducts, 734 ozonide reduction, 726 ozonization characterization, 737, 739 peroxydisulfate reactions, 1013, 1018 Alkali metal ozonides, 735-7 Alkaline peroxide process, pulp and paper bleaching, 623... 

The O3 (ozonide) ion is the only well-established species containing more than two oxygen nuclei. Two types of Oj have been reported and have been characterized mainly by EPR. The evidence for other species is weak and their existence has not been substantiated by direct observation. 

However, it must be borne in mind that in previous work, H2 did not react with a triangular array of O ions to form OH" ions (354). If such a reaction with H2 occurred, then the O" ions would no longer be available for Oj formation. Moreover, the reaction of pairs of O ions with oxygen should lead to pairs of O J ions which would have an abnormal EPR spectrum if they can be seen at all. In fact, the g tensor is as expected for isolated OJ ions. The CoO-MgO system behaves as CaO for the formation of Oj, i.e., via invisible O ions. The ozonide ions characterized by a three-g-value EPR signal (2.0025, 2.012, 2.017) do not exhibit any superhyperfine interaction with cobalt nuclei, suggesting that they are adsorbed on Mg2+ ions (110). Depending on the system (MgO, CaO, CoO-MgO) and the experimental conditions, the ozonide ion Oj disappears irreversibly between 25° and 130°C. In the case of MgO (333,334), OJ ions are formed when O J ions are destroyed, whereas for CaO (158) and CoO-MgO (110) the evidence is not clear. 

In conclusion, it appears that the classical ozonide 03 ion can be regarded as a well-characterized species on oxide surfaces. In contrast, the situation on the characterization of the so-called anomalous 03 complex is quite different. It is not possible at present to provide a clear theoretical explanation of the observed g values on the basis of an 03 species and the available I70 data is consistent with interaction with only two oxygen nuclei. The identity of this species must be regarded as uncertain at this stage and on the whole is more consistent with a complex adduct species, which may involve... 

The ozonide ion O3 has been clearly characterized by EPR and reflectance spectroscopy. Labeling experiments with 170 indicate that the O3 species contains three inequivalent oxygens forming a bond angle of about 110° and that it decomposes slowly at room temperature to form O ". A second type of species has been reported as O3 but has very different characteristics, since it is stable only at low temperatures and labeling experiments with 170, which indicate two equivalent nuclei, are difficult to interpret the balance of the evidence points toward a more complex polyoxygen species (see Section V,A). The data for O4 indicates that it is likely to exist on the surface under special conditions and we expect to see this confirmed by further studies. 

The first normal ozonide, the ozonide of 1,2-dimethylcyclopentene, was isolated and characterized as early as 1953 by Criegee.597 Ozonides were later observed by... 

---