Ozonolysis stoichiometry

The collection of products from the ozonolysis of seed oils can be challenging to use in plastic products directly as prepared by ozonolysis and work-up, but may be more amenable to the isolation of individual components (diols, diacids) from which a predictable stoichiometry then can be derived [97-99]. 

Overoxidation of carbonyl products during ozonolysis can be prevented by addition of tetracyanoethylene to the reaction mixture. The stoichiometry of the reaction is then ... 

Stoichiometry of the Reaction. Upon ozonolysis of 23 in inert solvents (pentane, methylene chloride, 1,1,2,2-tetrachloroethane) or without solvents, the originally colorless solutions turned light brown within minutes after the ozonolysis began and gradually assumed the typical deep red color of dissolved bromine. Unreacted ozone began to pass the reactor a few minutes after the ozonolysis began, and at any time thereafter the amount of ozone produced surpassed the amount of ozone consumed (Figure 2). This result was undoubtedly caused by the decreased reactivity of the dibrominated double bond in 23. 

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-... 

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... 

Reaction Stoichiometry. The results of the stoichiometry study (see Table II) were varied but did suggest a 1 1 ozone mercurial ratio for the cleavage of a carbon-mercury bond. Several problems were evident in such a study. Since mostly only the highest oxidation states for carbon were observed in the products of partial ozonation of 1°, 2°, and 3° organomercurials, it could be assumed that ozonolysis of the C—Hg bond involved the slowest step in the total reaction sequence. Hence, some... 

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