Alizarin

Alizarin is an organic compound in the anthraquinone family, specifically 1,2-dihydroxyanthraquinone. Its chemical formula is C14H8O4, and it features two adjacent hydroxyl groups on the anthracene skeleton, which give it properties as a phenolic red dye.

Historically, alizarin was the principal red dye obtained from the madder plant, Rubia tinctorum, and was widely used in textile dyeing and as a lake pigment in painting. The natural dyeing tradition dates back centuries, with alizarin producing a deep red to crimson color when mordanted on fabrics.

In the late 19th century, Adolf von Baeyer and collaborators developed synthetic routes to alizarin from coal-tar derivatives, leading to large-scale production. This synthetic availability contributed to the decline of madder cultivation in Europe and to the emergence of modern dye chemistry. For much of the 20th century, alizarin and its derivatives were among the most important red dyes, though they have since been supplemented or replaced by newer dyes and pigments in many applications.

Chemically, alizarin can form metal complexes with various mordants, affecting color and fastness. In pigment form, the aluminum lake of alizarin is known as alizarin crimson, a widely recognized historical pigment in art. Although less dominant in contemporary industry, alizarin remains of interest for study in organic chemistry, pigment technology, and historical dyeing practices.

Safety and handling follow standard practices for organic dyes and pigments, with attention to potential skin or eye irritation and environmental considerations in production and disposal.