Generation and trapping of free radicals from phthalhydrazyde and 5-nitrophthalhydrazide

The oxidation of phthalhydrazide 1 with t-butyl-hypochlorite in anhydrous a cetone yields 1,4-phthalazindiione 2 which upon reaction with 1,3-diphenyl- benzo-iso-furan 3 does not lead to the expected Diels-Alder adduct 4 bur gi ves a compound 5 known improperly as a dimer of phthalazindione 2.(1) Phtha lhydrazide and 5-nitro-phthalhydrazide 6 are oxidized with lead tetraacetat e in the presence of 3,5-di-t-buryl-nitrozobenzene 15. The generation of fr ee radicals is revealed through RPE techniques.