INTERPHASE PROCESSES INVOLVING HYDRAZINE DERIVATIVES - III - THE REACTION OF 2,2-DIPHENYL-1-PICRYLHYDRAZYL WITH HO- ANION IN THE PRESENCE OF CROWN-ETHERS

This study has evidenced the presence of hydroxyl free radical (HO .) in a two-phase system containing the following partners; a crown ether (CE), an alkaline base M+HO- and the free stable radical 2,2-diphenyl -1-picrylhydrazyl (DPPH) in an organic solvent. The process is an inte rphase catalysis of redox type implying electron transfer (ET) and sim ultaneous formation of hydroxyl radical and supramolecular complex (CE ...M)+DPPH-. In secondary homolytical processes, mono-and di-nitro par a-phenyl substituted derivatives of DPPH-H formed. The mechanism was e lucidated by identification of chemical species formed with the aid of TLC, UV-VIS, EPR, H-1-and C-13-NMR. The optimal conditions for such a process were determined by systematic studies on the nature and conce ntration of partners and of the two-phase system approached, liquid-li quid or solid-liquid.