The reaction between 2,2-diphenyl-1-picrylhydrazyl and bromine

The reaction between 2,2-diphenyl-1-picrylhydrazyl and bromine in solution bas been studied at several temperatures. Despite the literature, reporting simple phenyl bromination products, a substantial yield of nitration products is observed. These have been identified by use of thin-layer chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. Among various products, 2-(p-nitrophenyl)-2-phenyl-1-picrylhydrazine is a major one at room temperature and above. It is thought that this compound is formed by reaction of DPPH with NO2, displaced from ortho nitro groups in the picryl rings by bromine. Yields were found to vary, depending on experimental conditions, with the temperature and the rate of bromine addition as primary controlling factors.