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Yellow plate-like crystals. Rubiadin is one of the natural dyes extracted from madder roots and other Rubiaceae family plants. It dissolves in alkalis to form a red solution and turns yellow in acids.

Synonyms and Related Terms

1,3-hydroxy-2-methylanthraquinone; CI 75350; rubiadina (Port.)

Other Properties

Soluble in ethanol, ether, benzene. Insoluble in boiling water, lime water.

Absorption max = 246, 280, 415 nm.

Composition C15H10O4
Melting Point 302
Molecular Weight mol. wt. = 254.24

Additional Information

H.Schweppe, J.Winter, "Madder and Alizarin", Artists Pigments, Volume 3, E. West FitzHugh (ed.), Oxford University Press: Oxford, 1997.

Sources Checked for Data in Record

  • Artists' Pigments: A Handbook of their History and Characteristics, Elisabeth West FitzHugh, Oxford University Press, Oxford, Vol. 3, 1997 Comment: H.Schweppe, J.Winter, "Madder and Alizarin"