Natural alizarin is a red colorant extracted along with purpurin from the roots of the madder plant, Rubia tinctoria. The chemical name for alizarin is 1,2-dihydroxyanthraquinone. It has been used as a dye and pigment since ancient times. The colorant was first isolated in 1862 by Colin and Robiquet in France. The synthetic form of alizarin was first made in 1868 by Carl Graebe and Carl Lieberman, from anthracene. Synonyms: madder; alizarine; 1,2-dihydroxyanthraquinone; Natural Red 6, 8-12; CI 75330. Museum of Fine Arts, Boston (2000). [J. Cassar, R. de Angelis]