“ It may be prepared by distilling diphenylene ketone over zinc dust, or by heating it with hydriodic acid and phosphorus to 150–160° C.; and also by passing the vapour of diphenyl methane through a red hot tube. It crystallizes in colourless plates, possessing a violet fluorescence, melting at 112–113° and boiling at 293–295° C. By oxidation with chromic acid in glacial acetic acid solution, it is converted into diphenylene ketone (C6H4) 2·CO ”