Copper phthalocyanine

Copper phthalocyanine (CuPc), also called phthalocyanine blue, phthalo blue and many other names, is a bright, crystalline, synthetic blue pigment from the group of phthalocyanine dyes. Its brilliant blue is frequently used in paints and dyes. It is highly valued for its superior properties such as light fastness, tinting strength, covering power and resistance to the effects of alkalis and acids. It has the appearance of a blue powder, insoluble in most solvents including water. The discovery of metal phthalocyanines can be traced to the observation of intensely colored byproducts from reactions of phthalic acid (benzene-1,2-dicarboxylic acid) or its derivatives with sources of nitrogen and metals. CuPc (copper phthalocyanine) was first prepared in 1927 by the reaction of copper(I) cyanide and o-dibromobenzene, which mainly produces colorless phthalonitrile as well as an intensely blue by-product. A couple of years later, workers at Scottish Dyes observed the formation of traces of phthalocyanine dyes in the synthesis of phthalimide by the reaction of phthalic anhydride and ammonia in the presence of metallic iron. In 1937, DuPont started producing copper phthalocyanine blue in the USA under the trade name Monastral Blue after it had been previously launched in Great Britain (ICI) and Germany (I.G. Farbenindustrie) in 1935. Difficulty was experienced in forming stable dispersions with the first alpha forms, especially in mixtures with rutile titanium, where the blue pigment tended to flocculate. The beta form was more stable, as was the improved stabilized alpha form. Today, there are even more isomeric forms available. The substance, IUPAC name , is known by many names such as monastral blue, phthalo blue, helio blue, thalo blue, Winsor blue, phthalocyanine blue, C.I. Pigment Blue 15:2, copper phthalocyanine blue, copper tetrabenzoporphyrazine, Cu-phthaloblue, P.B.15.2, C.I. 74160, and British Rail Blue. Numerous other trade names and synonyms exist. The abbreviation "CuPc" is also used.