The procedure described in this paper is very reliable. The ozone should be used in a fully functional fume hood as described.
1. Synthesized 10.1 g of crude diphenaldehyde starting from 10.0 g of phenanthrene.
2. The crude 1H-NMR of product is 80% clean and was easily recrystallized from 70% aqueous ethanol (30 mL) to yield pure diphenaldehyde (8.8 g, 74%).