Alizarin

Alizarin is a red anthraquinone dye once extracted from madder root and now commonly made synthetically. It binds strongly to metal ions, making it useful as a textile dye and pigment.

Anthraquinone: An aromatic organic compound built from three fused rings, with ketone groups on the central ring. Alizarin is a hydroxylated anthraquinone, and this scaffold gives it its characteristic chemistry.
Madder: A plant genus whose roots contain red anthraquinone dyes, including precursors of alizarin. Madder roots were the traditional source from which alizarin was extracted.
Turkey red: A durable, vivid red textile color historically produced on cotton using madder and a complex mordanting process. Alizarin is the key red colorant associated with this celebrated madder-dyeing tradition.
Synthetic organic chemistry: The branch of chemistry concerned with constructing organic compounds through planned chemical reactions. Alizarin synthesis showed that a natural plant colorant could be assembled from simpler chemicals.
Mordant dye: A dye that forms a colored complex with a metal salt attached to a fiber or other surface. Alizarin's metal complexes help it attach to textiles and produce durable shades.
Madder dye: A natural red dye mixture obtained from the roots of madder plants. Alizarin is the principal coloring component associated with this historical dye.
Alizarin crimson: A deep red artists' pigment name historically associated with alizarin lake and also used for modern mixtures. It carries alizarin's name into artists' paints, though formulations vary.
Coal-tar dye: A synthetic dye historically manufactured from compounds obtained during coal processing. Early commercial alizarin was produced from anthracene derived from coal tar.
Alizarin lake: An insoluble pigment made by precipitating alizarin with metal ions, especially aluminum or calcium. This pigment form turns dissolved alizarin into a paint color.
Carl Graebe: A German chemist who helped establish the structure and synthesis of alizarin. Graebe and Carl Liebermann developed an early route to synthetic alizarin.

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