Paramagnetic Resonance Study of Liquids during Photolysis. II. Acetone and Solutions Containing Acetone

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Abstract
Paramagnetic resonance spectra in liquid acetone and acetone solutions were studied during the course of intense irradiation with ultraviolet light. In the presence of RH, an alcohol or ether, which served as a good hydrogen donor, both radicals of the reaction CH3COCH3+RH→(CH3)2ĊOH+Rwere seen. The abstracted H atom was taken from the carbon alpha to the O atom of the alcohol or ether. When pure liquid acetone was photolyzed, both radicals of the reaction CH3COCH3+CH3COCH3→(CH3)2ĊOH+ĊH2COCH3were seen. In addition some ĊH3 was seen. Higher concentrations of ĊH2COCH3 and ĊH3 were produced by photolyzing acetone containing 1% H2O2. In the latter case, it is believed that the radical OH was produced from the H2O2. The OH radical then abstracted an H atom from acetone to give ĊH2COCH3. It is thought that ĊH3 resulted from the reaction CH2COCH3→H2C=C=O+ĊH3.Accurate measurements were made of the g values and hyperfine parameters for (CH3)2ĊOH, ĊH2OH, and CH3ĊHOH in both water-rich and acetone-rich solutions at room temperature; for CH3CHOCH2CH3 in acetone solution at room temperature; for CH3 in acetone at −53°C; for ĊH2COCH3 in acetone at room temperature and at −49.5°C; and for the radical resulting from the loss of one of the H atoms of dioxane in acetone solution at room temperature. It was found that the OH-proton hyperfine coupling of CH3ĊHOH in aqueous solution could be carried through the value zero by changing the temperature. Effects due to acid-catalyzed proton exchange of the OH proton of CH2OH and of (CH3)2COH with solvent protons were studied in aqueous solutions. These studies gave values for the mean lifetime of a radical between exchanges.

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