The natural-abundance 17O NMR spectra of 35 ozonides have been examined with the following results: Symmetrically tetrasubstituted ozonides and symmetrically disubstituted ozonides give only one signal each for the ether and the peroxide O atoms. Unsymmetrically tetrasubstituted ozonides bearing the electron-withdrawing groups CI, CN, or CF3, and also some unsymmetrically disubstituted ozonides, give two signals for the per oxide O atoms. Electron-withdrawing groups and ring stress in bicyclic ozonides cause downfield shifts in the -O-O- signals and even larger ones in the -O- signals. The range in which the signals appeared was 87-172 ppm for the ether O atoms and 263-336 ppm for the peroxide O atoms.
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