Use of 2,2-Diphenyl-1-picrylhydrazyl To Investigate the Chemical Behavior of Free Radicals Induced by Ultrasonic Cavitation

Article abstract of DOI:10.1021/j100212a034

The sonolysis of 2,2-diphenyl-1-picrylhydrazyl (DPPH) has been studied in methanol-water solutions in the presence of air, oxygen, and argon.It is found that, for a specific solvent composition, 83 percent of the reacted DPPH is reduced to 2,2-diphenyl-1-picrylhydrazine (DPPH2) with all the gases examined.The absolute amount of DPPH converted is greatest with oxygen and it is believed that the latter combines with the primary radicals produced in the cavitation process to give a greater concentration of stable free radicals which can readily diffuse out of the bubble to react with DPPH.The conversion of DPPH <*> DPPH2 decreases with increasing methanol concentration and it is believed to be due to the volatile alcohol inhibiting the cavitation process.