Natural products peroxide analysis

Synthetic operations involving ozonolysis lead to formation of aldehydes, ketones or carboxylic acids, as shown in Scheme 16, or to various peroxide compounds, as depicted in Scheme 7 (Section V.B.5), depending on the nature of the R to R substituents and the prevalent conditions of reaction no effort is usually made to isolate either type of ozonide, but only the final products. This notwithstanding, intermediates 276 and 278 are prone to qualitative, quantitative and structural analysis. The appearance of a red-brown discoloration during ozonization of an olefin below — 180°C was postulated as due to formation of an olefin-ozone complex, in analogy to the jr-complexes formed with aromatic compounds however, this contention was contested (see also Section V1I.C.2). 

It is, however, appropriate to point out that, whereas McDowell and Sifniades claim to have demonstrated by gas chromatography the formation of traces of acetyl peroxide, Calvert and Hanstdid not detect this peroxide when using infrared spectrophotometry. By use of infrared analysis, Osborne, Pitts, and Fowler were equally unable to detect acetyl peroxide among the photooxidation products obtained from acetone. The exact chemical nature of the product resulting from the interaction of two CHsCOa- radicals does not therefore seem to have been clarified. 

The reaction of diacyl peroxide with stannous chloride in acid solution in room temperature or at a slightly elevated temperature is used in the quantitative analysis of the peroxygen compounds [22], The reaction of the peroxygen compound with stannous chloride in the acid medium is apparently rapid and complete enough at room temperature to serve as a quantitative assay method. However, there is no information as to the nature of the decomposition products (i.e., radical or ionic). In the absence of other evidence, the most reasonable mechanism would appear to be a heterolytic process as shown in reaction (11) ... 

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