561-20-6

Indicator.

Cacotheline gives yellow crystals from H2O. It is then dried over H2SO4 which gives the dihydrate, and in a vacuum over H2SO4 at 105o it forms the anhydrous compound. The hydrochloride separates as the hydrate (on heating in vacuum at 80o) in orange-yellow prisms or plates, m 250o(dec) and forms a resorcinol complex which gives brown crystals from EtOH, m 325o, and a hydroquinone complex as dark red crystals from EtOH, m 319o. [Leuchs & Leuchs Chem Ber 43 1042 1910, Teuber Chem Ber 86 232, (UV: 242) 1953; complexes: Gallo Gazz Chim Ital 85 1441 1955.] It is used in the titrimetric estimation of Sn2+ ions [Szrvas & Lantos Talanta 10 477 1963]. [Beilstein 27 III/IV 8014.]