Synthesis of nitro-substituted dioxotetrahydrodioxapyrenes and 6H-dibenzo[b,d]pyran-6-one

Abstract

Methods for the synthesis of tri- and tetranitro-substituted 5,9-dioxo-4,5,9,10-tetrahydro-4,10-dioxapyrenes, 5,10-dioxo-4,5,9,10-tetrahydro-4,9-dioxapyrenes, and 6H-dibenzo[b,d]pyran-6-one were developed in a search for effective sensitizers for electrophotographic layers based on carbazole-containing polymers. The possibility of the production of nitro compounds that contain three vicinal nitro groups was demonstrated. Under severe nitration conditions 2,4,8-trinitro-6H-dibenzo[b,d]pyran-6-one is cleaved to give 2-hydroxy-2′-carboxy-3,5,4′-trinitro-biphenyl, which is resistant to cyclization to give the starting compound, evidently because of the existence of an intramolecular hydrogen bond between the hydroxy group and the nitro group.