There are three major groups of synthetic organic pigments used in artists’ paints-anthraquinone, azo, and phthalocyanine. The first, anthraquinone, was 1,2-dihydroxyanthraquinone (alizarin crimson) developed in 1868 in an attempt to understand the coloring properties of madder root. This discovery led to the development of several indanthrones, of which one has come into use among artists as indanthrone blue. http://forrestpaint.com/

The second group, azo, refers to a particular molecular arrangement among nitrogen-containing organic molecules. Although azo dyes were developed as early as 1880, it was the development of naphthol AS (naphthol red) in 1912 that heralded the birth of stable dye-pigments, which today include arylides (used to make hansa yellow, cadmium yellow hue), perinones (perinone orange), and naphthols (naphthol red, naphthol crimson, and cadmium red hue). http://forrestpaint.com/

The third major group is the phthalocyanine dyes (phthalocyanine blue and green). Phthalocyanine was first discovered in 1907. It was rediscovered several times after that until the 1930s, when it was developed for artists’ use. Out of this group came the quinacridones, of which gamma-quinacridone (quinacridone magenta) and Quinacridone Violet b (quinacridone violet) have become relatively commonplace. http://forrestpaint.com/