Alizarin orange

Description

Alizarin orange produces bright, orange needles or plates when precipitated from an acetic acid solution. It is used to dye cloth orange with an alum mordant or a red to violet color when used with an iron mordant. Alizarin orange is also used as an acid-base indicator. In aqueous solutions, it changes from an orange at pH 2.0 to a yellow at pH 4.0. In a saturated alcohol solution, alizarin orange changes from yellow at pH 5.0 to a purplish red at pH 6.5.

See also synthetic alizarin..

Synonyms and Related Terms

Mordant Orange 14; CI 58015; 3-nitroalizarin; 1,2-dihydroxy-3-nitroanthraquinone; anaranjado de alizarina (Esp.); orange d'alizarine (Fr.); arancio d'alizarina (It.); alaranjado de alizarina (Port.); Alizarine orange

Composition	C14H7NO6
Molecular Weight	285020

Authority

• Ralph Mayer, Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)

• Richard S. Lewis, Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• The Merck Index, Susan Budavari (ed.), Merck Research Labs, Whitehouse Station, NJ, 12th Edition, 1996 Comment: entry 235