The ozonolysis of suitably substituted alkenes

The solvent used in the latter case is dry ethyl chloride, which must be replaced by methanol before hydrogenation. Methanol when cooled to about — 20 °C is not attacked by ozone and can in many cases be used as the ozonisation solvent. In such cases the main product of addition of ozone to the alkene is not the usual ozonide, but is the methoxyhydroperoxide which, however, is also reductively cleaved to the aldehyde on hydrogenation. This ozonisation process may be mechanistically summarised as follows  

Cognate preparation. Azelaic hemialdehyde semicarbazone. Dissolve 7g (0.025 mol) of pure oleic acid in 30 ml of dry ethyl chloride (chloroform may be used but is less satisfactory), and ozonise at about — 30 °C. Remove the 

(1) The Adams platinum oxide catalyst gives satisfactory results in the reduction of ozonides. 

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Aldehydes and ketones can be obtained from the ozonolysis of suitably substituted alkenes. 

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