Nonmagnetic Isotopes Research Articles

Magnetic isotope effects in photochemical reactions. Observation of carbonyl oxygen-17 hyperfine coupling to phenylacetyl and benzoyl radicals. Oxygen-17 enrichment studies

The photochemistry of I70-enriched (at C=O) dibenzyl ketone (DBK), benzoin methyl ether (BME), and deoxybenzoin (DB) has been studied on porous silica and in homogeneous solution with the aim of enriching the recovered ketones with I7O [separation of magnetic (I7O) from nonmagnetic (l60, '80) isotopes]. I7O enrichment occurs with modest efficiencies on porous silica (a I 1.12); photolysis in aqueous micellar solution occurs but is complicated by oxygen exchange with water thereby obviating quanitative analysis of the enrichment. Steady-state ESR spectra are reported in toluene at 165 K. Hyperfine coupling of phenylacetyl and benzoyl radicals to the carbonyl oxygen is observed, with a(170) = 16.1 * 0.5 G.