Pyrene-4,5,9,10-tetraone was synthesised from Pyrene-4,5-dione Using CrO3. The specific steps are as follows:
A 250 mL round-bottom flask fitted with a stirring magnet and a reflux condenser was charged with pyrene-4,5-dione (5.0 g, 21.6 mmol) and 150 mL of glacial acetic acid. The resulting orange slurry was stirred at reflux (the oil bath surrounding the reaction flask was kept at 130 °C) for 10 min. Solid CrO3 (12.0 g, 0.12 mol) was added in portions over the course of 3 min, after which the reaction mixture was refluxed overnight. The dark green solution was poured into 300 mL of H2O, and the crude product was collected by filtration and dissolved in 15 mL of 96% H2SO4. Pouring the sulfuric acid solution into 300 mL of H2O precipitated the tetraone, which was collected by filtration and washed on the filter with copious amounts of H2O until neutral pH. The wet product was dried in the heating oven at 120 °C to afford 4.0 g (71%) of a custard-yellow solid, pure by TLC and 1H NMR. The tetraone product can be further recrystallized from refluxing benzonitrile (40 mL per 1 g of the tetraone) to produce long needles, which are then dried in the oven at 120 °C to remove the residual crystallization solvent.
[1] OMOLOLA BALOGUN;, et al.
Syntheses of Pyrene-4,5-dione and Pyrene-4,5,9,10-tetraone[J]. Journal of Organic Chemistry, 2025, 90 41: 14835-14838. DOI:10.1021/acs.joc.5c01542.
