
%0 Journal Article
%A Evans, NA 
%A Leaver, IH 
%T Dye sensitized photooxidation of 1,3-Diphenyl-2-pyrazoline
%J Australian Journal of Chemistry
%D 1974/08/01
%V 27
%N 8
%P 1797-1803
%K 
%R https://doi.org/10.1071/CH9741797
%U https://www.publish.csiro.au/paper/CH9741797 
%X Dye sensitized photooxidation of 1,3-diphenyl-2-pyrazoline in methylene chloride yields 1,3-diphenyl- pyrazole and in methanol yields 1,3-diphenylpyrazole and &#946;,&#946;-dimethoxypropiophenone. The formation of 1,3-diphenylpyrazole is quenched by the singlet oxygen quencher &#946;-carotene, whereas the formation of &#946;-dimethoxypropiophenone does not appear to be affected. The photooxidation in methanol shows a large deuterium isotope effect, the rate being approximately ten times faster in methanol[D4] than in methanol. Under anaerobic conditions, 1,3-diphenyl-2-pyrazoline quenches the phosphorescence of eosin Y and rose bengal B with quenching rate constants 1.0 x 108 and 3.0 x 108 1, mol-1 s-1, respectively. Photobleaching of the dyes is shown to occur by reduction to the semi-reduced dye radicals. 
