THERMOCHEMISTRY OF OZONIDES DECOMPOSITION

Franco Cataldo

Abstract


Little is known about ozonides and their decomposition notwithstanding the growing interest for these compounds in medicinal chemistry or as intermediates in chemical synthesis. Using the Van Krevelen’s group increment approach we have calculated the theoretical decomposition enthalpies of a series of olefins ozonation products adopting the simple assumption that the ozonides decompose into aldehydes and carboxylic acids but also by-products of ozonation like polyozonides, bis-peroxides and polycarbonyloxide decompose into the same products. It was found that all the homologous series of 1-olefin ozonides decompose with a ΔHdec = -267 kJ/mol and considering the other by-products the decomposition range of the entire crude ozonation mixture of 1-olefins is given by ΔHdec = -272±20 kJ/mol. For the homologous series of symmetrical olefins of the type R-CH=CH-R the canonical ozonides with 1,2,4-trioxolane ring decompose with ΔHdec = -298 kJ/mol while considering the other by-products the decomposition range of the entire crude ozonation mixture of symmetric olefins is given by ΔHdec = -288±10 kJ/mol. Asymmetric olefins of the type R-CH=CH-R’ with R ≠ R’can be represented by the monounsaturated fatty acids series or by the methyl and the ethyl esters of fatty acids. Also for this homologous series the canonical ozonides with 1,2,4-trioxolane ring decompose with ΔHdec = -298 kJ/mol while considering the other by-products the decomposition range of the entire crude ozonation mixture of symmetric olefins is given by ΔHdec = -288±10 kJ/mol.

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DOI: http://dx.doi.org/10.17628/ecb.2014.3.227-233

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