Alizarin blue

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Alizarine blue crystallizes in brownish-violet needles from a benzene solution. When prepared in a saturated alcoholic solution, alizarin blue is used as an acid-base indicator. It changes from pink at pH 0.0 to yellow at pH 2.6. It also changes from yellow at pH 6.0 to green at pH 7.6.

See also Alizarin.

Synonyms and Related Terms

5,6-dihydroxynaphtho[2,3-f]-quinoline-7,12-dione; 7,8-dihydroxy-5,6-phthaloquinoline; CI 67410; bleu d'alizarine (Fr.); blu d' alizarina (It.); azul de alizarina (Port.); Alizarine Blue R;

Physical and Chemical Properties

Soluble in glacial acetic acid, amyl alcohol and hot benzene. Slightly soluble in ethanol, ether and cold benzene. Insoluble in water.

Composition C17H9NO4
Melting Point 268-270 C
Molecular Weight 291.25

Resources and Citations

  • 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 234

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