Alizarine Crimson

Natural alizarin, together with purpurin and pseudopurpurin, is the principal red chromophore (colourant) in the root of the madder plant, Rubia tinctorum L.¹, the most important species of the Rubiaceae family. Madder had been widely used since prehistoric times for its bright, intense, cool red colour².

The plant is native to Asia and was initially cultivated chiefly around Adrianople, Smyrna and the island of Cyprus in the ancient Greek world and needed three years to be cropped. Its cultivation was later introduced into Italy as a result of the Crusades³.

The ancient Greek physician and pharmacologist Pedanius Dioscorides (Πεδάνιος Διοσκουρίδης) (c.10-c. 90 A.D.), regarded as the father of pharmacognosy, named the plant erythrodanon in his encyclopaedic work Περὶ ὕλης ἰατρικῆς (Peri hulēs iatrikēs, meaning “On Medical Material"⁴). The term “erythro” refers to “red”.

The alizarin compound was successfully isolated in 1826 by the French chemists Pierre Jean Robiquet (1780-1840) and Jean-Jacques Colin (1784-1865), after which numerous attempts were made to produce this highly valued colourant synthetically⁵.

Such was the appreciation of the colour that the successful production of synthetic alizarin from a constituent of coal tar in 1869 by the German organic chemists Carl Graebe (1841-1927) and Carl Theodor Liebermann (1842-1914) was enthusiastically received.

Immediately after the publication of their findings, the English chemist and entrepreneur William Henry Perkin (1838-1907) independently researched and achieved a less complicated method for synthesising alizarin from coal tar, which he subsequently patented⁶.

Synthetic alizarin was identical to, and more readily available than, the plant-derived colourant. It rapidly replaced natural madder in virtually every application, including artists’ colours. The cultivation of the original plant was consequently largely abandoned within a few years, while the commercialisation of synthetic alizarin flourished, reaching its peak around 1900⁷.