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8688537 
Journal Article 
On the Mechanism of Alkane Oxidation by Ozone in the Presence and Absence of FeCl31 
Hellman, TM; Hamilton, GA 
1974 
Yes 
Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 
96 
5 
1530-1535 
English 
The characteristics of the reaction of ozone with alkanes at ambient temperatures have been investigated further. When O2 is replaced by N2 as the O3 carrier gas the following characteristics are not altered significantly: the ratio (0.3) of ketone to alcohol products formed from cyclohexane; the stereochemistry (60-70% net retention of configuration) of tertiary alcohol formation; and the relative reactivities (1:13:110) of primary, secondary, and tertiary carbon-hydrogen bonds. The stereochemical results are unchanged by performing the ozonation in polar solvents, but a somewhat higher (82 %) net retention of configuration is observed in an alkane solvent (octadecane) of higher viscosity, and lower per cent retentions are observed when additives or solvents with which O3 reacts are present. When the ozonations are performed in the presence of FeCl3, alcohols are formed with virtually 100% retention of configuration. Alkyl halides with essentially 100% inversion of configuration are also formed under such conditions. The effects of FeCl3, diphenylamine, and combinations of the two on the ratios of products (ketone, alcohol, and alkyl halide) formed on ozonation of cyclohexane were also determined. The Hammett p for the oxidation of substituted toluenes was found to be —2.07. The mechanism which best fits the data is one in which the ozone and alkane react to give either singlet O2 and the alcohol with retention of configuration, or triplet O2 and a triplet solvent-caged radical pair. The latter is either trapped by FeCl3 to give alkyl halide, or the radicals diffuse apart and react further to give the other observed products. 1974, American Chemical Society. All rights reserved.