cinquasia red

Quinacridone is an organic compound used as a pigment. Numerous derivatives constitute the quinacridone pigment family, which finds extensive use in industrial colorant applications such as robust outdoor paints, inkjet printer ink, tattoo inks, artists' watercolor paints, and color laser printer toner. As pigments, the quinacridones are insoluble. The development of this family of pigments supplanted the alizarin dyes.

==Synthesis== The name indicates that the compounds are a fusion of acridone and quinoline, although they are not made that way. Classically the parent is prepared from the 2,5-dianilide of terephthalic acid (C6H2(NHPh)2(CO2H)2). Condensation of succinosuccinate esters with aniline followed by cyclization affords dihydroquinacridone, which are readily dehydrogenated. The latter is oxidized to quinacridone. Derivatives of quinacridone can be readily obtained by employing substituted anilines. Linear cis-Quinacridones can be prepared from isophthalic acid.