Interaction of ozone with double

The Interaction of Ozone with Double Bonds Containing Vinyl Bromide Moieties... 

T he ozonolysis of pure hydrocarbon olefins has been studied by gen-erations of chemists ever since 1905 when Harries established the interaction of ozone with double bonds. During this continued research practically all aspects of the ozonolysis reaction have been extensively scrutinized, starting from the nature and products of the initial ozone-double bond interaction, via the mechanistic and stereochemical course of the ozone cleavage, to the correlation between the nature of the starting material and the reaction products. Consequently, the ozonolysis of hydrocarbon olefins is rather well understood. 

Interaction of ozone with a double bond is one of the most specific reactions of imsaturated compounds. This reaction is widely used in quantitative and qualitative analyses, synthesis, and chemical technology [1-3]. It is one of the best-studied reactions, which is described in hundreds of works and dozens of reviews and monographs published in the past 40 years [1-6]. The mechanism of this reaction was studied both theoretically and experimentally during the past 50-60 years until recently, it has been considered as an imambiguously established one. Many authors consider it as a classic example of simultaneous (coordinated) 1.3-addition with the formation of five-membered cyclic primary ozonide in the first event (the Kriege mechanism [7]) ... 

The authors [23] applied the method of density fimctional (exchange-correlation functional B3LYP) and calculated the profdes of the potential energy for the interaction of ozone with ethylene. It was shown that, according to the scheme of ozonolysis of ethylene, the reaction pathway through the direct epoxidation of the double C=C bond requires high energy of activation and is improbable, both for thermochemical and photochemical reactions of ozonolysis. 

When this work was initiated, there were only a few scattered reports in the literature concerned with the interaction of ozone and halogenated double bonds. The bulk of these reports dealt with the ozonolysis of substrates containing both halogenated and non-halogenated double bonds. In all of these cases the non-halogenated double bond was attacked preferentially by ozone, and only products derived from that kind of reaction were described. 

Other theoretical studies of ozone and its excited states have been previously reported and also indicate a relatively low lying state corresponding to a six jr-electron cyclic structure. In particular, recent ab initio calculations using the generalized valence bond and configuration interaction methods with a double zeta basis set, predict that trioxirane lies about 35 kcal/mol higher in energy than ozone but that it is a potential minimum. 

The cyclopropane chemical reactivity, which closely resembles that of an olefinic double bond, stems from the electronic properties of this three-membered carbocycle Effectively, cyclopropyl and olefinic groups interact with neighbouring 7c-electron systems and p-electron centres they both add acids, halogens and ozone, undergo catalytic hydrogenation and cycloaddition, form metal complexes, etc. 

It can thus be seen that zwitterions IV and V would be stabilized by the interaction of the alcohol with them, and the ozonide would have no opportunity to form and decompose abnormally. Whether zwitterions IV and V are formed in equal amounts depends upon the groups which are attached to the double bond and the carbon atom to which the ozone molecule initially adds. The final products, VI and VII, may be considered as hemiperacetals or hemiperketals and could be isolated only under special conditions. However, they can be easily decomposed with either sulfurous acid or sodium bisulfite and the ketones or aldehydes formed determined quantitatively as their 2,4-dinitrophenylhydrazones. 

Based on these considerations, Croft prepared six formulations containing various combinations of NBR and NBR/PVC with CR and SBR and measured their oil, heat and ozone resistance, physical properties, and adhesion characteristics. Whereas the physicals are satisfactory for aU compounds, formulations based on NBR, NBR/PVC with CR performed better on heat and oil aging than the compounds containing SBR as shown in Tables 11.6 and 11.7. However, the adhesion is better with the latter compounds. It has been suggested that cuprous sulfide formed on the wire surface interacts with the double bond in SBR to provide the improvement in adhesion. 

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