The Absorption Spectra of Δ^10,10'-Bianthrone, Helianthrone and Mesonaphthobianthrone in Concentrated Sulfuric Acid

Photooxidative transformations of anthrone, bianthronyl, and bianthrone in acid solution

“…In fact these peaks are at the same wavelengths as the maxima reported for the absorption of helianthrone in sulfuric acid. 15 Furthermore, the isosbestic point at 315 nm in Figure 3 coincides with the wavelength of equiabsorptivity of 9,10, and 15. This not only reinforces the suggested 9 -* 15 -10 photoxidative mechanism but also explains the fortuitous occurrence of an isosbestic point at 315 nm.…”