Ozonization olefin

The principal organic reaction of ozone is its addition to the carbon-carbon double bond of an ethylenic compd. The resulting ozone-olefin addition compd is known as an ozonide. Decompn of the ozonide gives a mixt of oxygenated products containing carbonyl compds and acids. 

The primary ozone-olefin addition product splits into a molozonide zwitterion (3). The zwitterion (3) then stabilizes by splitting into a carbonyl compd (4) and another zwitterion (5). 

Hanst, P.L., Stephens, E.R., Scott, W.E., Doerr, R.C. (1958) Atmospheric Ozone-Olefin Reactions. Franklin Institute, Philadelphia, Pa. 

Bromine Ammonia, carbides, dimethylformamide, fluorine, ozone, olefins, reducing materials including many metals, phosphine, silver azide... 

Furthermore, it has been noted that when the rate of the oxygen atom-olelin reaction and the rate of the ozone-olefin reaction are totaled, they do not give the complete hydrocarbon consumption. This anomaly is also an indication of an additional process. 

If ozone-olefin adducts are stable in the gas phase, as a recent study hinted, then they are almost certainly present in the urban atmosphere. Their concentrations will depend on their stability in the sunlit atmosphere. If present, they are expected to be very reactive. 

Atkinson, R., B. J. Finlayson, and J. N. Pitts, Jr. Photoionization mass spectrometer studies of gas phase ozone-olefin reactions. J. Amer. Chem. Soc. 95 7592-7599, 1973. 

McAfee, J. M., A. M. Winer, and J. N. Pitts, Jr. Infrared Product Analysis of Ozone-Olefin Reaction by Fourier Interferometry. Paper Presented at CODATA... 

Much evidence has been accumulated that the ozone-olefin reaction has a predominant role in aerosol formation from alkenes, cyclic olefins, diolefins, and other unsaturated compounds. Free radicals are formed in the reaction and can react further, along with nitric oxide and nitrogen dioxide, either with the various intermediates or with the olefin itself (see the recent review by Pitts and Finlayson ). 

A mechanism has been proposed recently by O Neal and Blumstein for the gas-phase ozone-olefin reaction. This mechanism postulates that molozonide-biradical equilibrium is reached fast and postulates a competition between a-, 8-, and y-hydrogen abstraction reactions and the classical mechanism proposed by Criegee for the liquid-phase reaction. The main features of the Criegee mechanism (Figure 3-9) are the formation, from the initial molozonide, of the major carbonyl products and a second biradical intermediate, the zwitterion. The decomposition pathways of the zwitterion comprise unimolecular re-... 

FIGURE 3-10 Gas-phase ozone-olefin reaction the O Neal and Blumstein mechanism J... 

With Equation 3-5, the general problem can be reduced to the ozone-olefin system ... 

Reactions with intermediates of the ozone-olefin reaction ... 

Becker, K. H., U. Schurath, and H. Seitz. Ozone-olefin reactions in the gas phase. 

Burton. C. S., E. Franzblau, and G. M. Hidy. Aerospl Formation from Ozone-Olefin Reactions, Abstract COLL 128. In Abstracts of Papers. 167th National Meeting, American Chemical Society, Los Angeles, Califomb, March 31-April 5, 1974. 

Becker, K. H., U. Schurath, and H. Seitz. Ozone-olefin reactions in the gas phase. 1. Rate constants and activation energies. Int. J. Chem. Kinetics 6 725-739, 1974. 

Kendrick, J. B., Jr., J. T. Middleton, and E. F. Darley. Chemical protection of plants from ozonated olefin (smog) injury. Phytopathology 44 494-495. 1954. 

Acroldn concentration, 186,187 Adenosine triphosphate, effect of ozone on lung concentration of, 354 Aerosol carbon balance, 50 Aerosol formation, 4, 14, 674-76 ability index, 61 diemical medianisms of, 72 hydrox]4 radical-aromatic hydrocar> bon reaction, 76-81 ozone-olefin reaction, 72-76 condensable species vapor pressure and, 86-90,101... 

Cotton, effect of oxidants on, 462,687 Cotton fiber, ozone damage to, 665 Coulombmetry. See Amperometric analyzers <>i ee mechanism, for liquid-phase ozone-olefin reaction, 72-74, 76 Cydic olefins, 4,60,76 aerosols from, 70-72,83,88 importance of, 104... 

Finlayson, B. J., J. N. Pitts, Jr., and H. Akimoto, Production of Vibrationally Excited OH in Chemiluminescent Ozone-Olefin Reactions, Chem. Phys. Lett., 12, 495-498 (1972). 

Pryor WA, Prier DG, Church DF. Detection of free radicals from low-temperature ozone-olefin reaction by ESR spin trapping evidence that the radical precursor is a trioxide. J Am Chem Soc 1983 105 2883-2888. 

This mechanism proceed via a peroxidic Zwitterion what is now largely accepted by all the scientific community. Product 1, an ozone-olefin adduct is a very unstable compound giving rapidly product 3, probably through intermediate 2. The Criegee intermediate 3 can lead to different structures like ... 

Niki, H., Maker, P.D., Savage, C M., Breitenbach, L.P. (1983) Atmospheric ozone-olefin reactions. Environ. Sci. Technol. 17, 312A. 

Further characterization of the ozone—mesitylphenylethylene complex produced at —150 °C was done by NMR and visible spectral studies. The low temperature NMR spectra of the starting olefin, the red complex (ozonized olefin at —150°C) and the dilute reaction mixture at —135°C containing the epoxide of 1-mesityl-1-phenylethylene are described in Table III. The —150 °C solutions of the olefin and the complex contain the same bands, the only difference being that the peaks were shifted slightly upfield in the formation of the complex. Such is typical of tt complexes with very little charge transfer, such as iodine and tetracyano-ethylene complexes of various aromatic molecules (5, 6). When the temperature of the ozonized reaction mixture was allowed to rise above about —145 °C, the NMR spectrum changed, giving rise to the characteristic peaks of the epoxide of 1-mesityl-l-phenylethylene. 

Pi complexes have frequently been proposed in initial ozone—olefin interactions (I, 8, 9,10). To our knowledge, however, the ones reported here are the first ever observed and characterized. The fact that complexes but no radicals were observed during ozonation of the ether and ester of trimesitylvinyl alcohol indicates that the hydroxy proton was essential to dissociation of the complexes to radicals. Further discussion of the significance of these complexes to ozonation of olefins, as well as a discussion of the ir systems involved, will be given elsewhere. 

It was now important to examine the question of a possible stereochemical influence on diperoxide formation. We have approached this problem initially by ozonizing olefins of type 2. When either cis- or trans-3,4-dimethyl-3-hexene are ozonized, presumably a single stereoisomeric pair of diperoxides can be formed. In fact, this case is complicated by the possibility of two trans-diperoxide conformers being produced. The cis-diperoxide conformers are identical. Ozonolysis of cis-3,4-dimethyl-3-hexene, 8, for example, could give the diperoxides, cis-l,3-dimethyl-l,3-diethyl-2,3,5,6-tetraoxacyclohexane, 11a, and rans-l,3-dimethyl-l,3-di-ethyl-2,3,5,6-tetraoxacyclohexane, lib, with the latter capable of existing as conformers lib and lib with trans-diaxial methyl and trans-diaxial ethyl substituents, respectively. 

Similar conclusions are drawn by Cvetanovic et al. from their results of ozonization of alkenes in the gas phase (9) and in CC14 solution (10). The rate constants for the ozonolysis of chloroethylenes and allyl chloride, in CC14 solution, indicate (11) that the rate of ozone attack decreases rapidly as the number of chlorine atoms in the olefin molecules is increased. However, to explain the departures from simple correlations, in some cases steric effects and the dipolar character of ozone had to be invoked (10). The relevance of the dipolar character of ozone in its reactions has also been stressed by Huisgen (12), who provided evidence that the ozone—olefin reaction is usually a 1,3-dipolar cycloaddition. 

On the basis of the evidence (10) that, in solution, the ozone—olefin reaction takes place with a 1 1 stoichiometry, the consumption of olefin i may be written... 

Table II presents a summary of the values of kreY which were obtained in the way just indicated, for p-methylstyrene, in CC14 solution, with respect to styrene. These results indicate that kTei is invariant with respect to the ozone flow rate, the temperature of ozonolysis, and the olefin initial concentration. The fact that kreA is independent of temperature in this case is readily understood when it is considered that the experimental activation energies for the ozone-olefin reaction are likely to be very similar for p-methylstyrene and styrene.

Perhaps the most interesting point which emerges from the results is that in ethylenes bearing electron-releasing alkyl substituents the ratedetermining step appears to be a nucleophilic process, as indicated by the positive p values. This does not contradict the assumption that the first step in the ozone—olefin reaction is an electrophilic attack of ozone on the carbon-carbon double bond. The present observations also agree with some of the results obtained recently by Pritzkow et al. (16) for alkyl mono-substituted ethylenes in ethanol solution at — 60 °C. 

The nature and the distribution (Table II) of the ozonolysis products in conjunction with the probable modes of their formation allow also a qualitative rationalization of the observed ozone-olefin stoichiometry. Three reactions compete with ozone for the starting material, trans-2,3-dibromo-2-butene. These reactions are the formation of 3,3-dibromobutanone, 31, and the formation of the brominated products, 34 and 35. On the other hand, hydrogen bromide is oxidized to form bromine and water, which consumes ozone on top of the regular olefin— ozonolysis reaction. An attempt to explain the observed stoichiometry quantitatively did, however, not lead to a satisfactory correlation between the actual ozone consumption and the observed material balance. This... 

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