Stoichiometry ozone-olefin

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... 

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... 

To assess the quantitative correlations between ozone consumption, olefin consumption and product formation, experiments were carried out in the presence of 1,1,2,2-tetrachloroethane as an internal standard for NMR analyses. These experiments showed that only about half the equimolar amount of ozone was required to consume the olefin completely (Figure 3). This stoichiometry was obviously not the 1 1-stoichiometry usually found in the ozonolysis of hydrocarbon olefins and which is the basis for the quantitative assessment of the number of double bonds in organic molecules by ozonolysis. Attempts to explain this unusual stoi-... 

Wei and Cvetanovic (3) measured the reaction rates of ozone with olefins in the presence and absence of molecular oxygen and found that the relative rate constants were lower when O2 was absent. They also found that the reactions showed a 1 1 stoichiometry in the absence of O2 and 1 1.4 to 1 2.0 stoichiometry for different olefins in the presence of O2. 

Vapor-phase reaction between ozone and olefins is quite rapid, the overall reactions become complicated, and stoichiometry varies with the reaction pressures. A 3 mole per cent mixture of OTOne in oxygen reacts with methane, propane, i -butane, and isobutane at 25-50 C. The reaction of ozone with isobutane resulted in formation of ferf-butanol plus one-third to one-half as much acetone, the combined yield being about equivalent to ozone reacted. Acetone was formed from propane oxidation. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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