1,10-Phenanthroline-5,6-dione is an organic compound with the formula . It is the quinone derivative of 1,10-phenanthroline. The compound exhibits many reactions, including condensations with diamines to give quinoxalines and decarbonylation to give a diazafluorenone.
The compound is prepared by oxidation of 1,10-phenanthroline with a mixture of nitric and sulfuric acids. 5-Nitro-1,10-phenanthroline is an intermediate.