Arylide yellow
Composition and Properties of Arylide Yellow
Arylide yellow is one of the many variants of organic pigments containing the group of two nitrogen atoms —N=N— bound together by a double bond (monoazo group). The chemical formula is shown below.Hansa yellow light is rather stable in weak acids and bases but less stable than other members of the group of arylide pigments. Like many of the other organic pigments, it is not resistant to heat. The pigment meets the requirements for the lightfastness of artists’ paints. Arylide pigments tend to change their properties after having been solved in most of the usual solvents and show discoloration towards the red end of the spectrum.
Names of Arylide Yellow
Hansa Yellow Light, Hansa Lemon Yellow, Helio Yellow, Permanent YellowPY 3, CI 11710From the term aromatic denoting cyclic organic compounds with delocalized double bonds.
Preparation of Arylide Yellow
Hansa yellow light (PY 3) can be prepared in the following way: In the first step, a diazonium salt is prepared from 2-nitro-4-chloro aniline and sodium nitrite. In the second step, the diazonium salt is coupled with the substituted acetoacetanilide. The second step of the reaction is shown below.
History of Use
The first pigment of the arylide yellows group designated PY 1 (pigment yellow 1) was discovered in 1909 by Hermann Wagner in Germany. It started to be commercially available around 1925 and more widely used predominantly as a replacement for the toxic cadmium yellow after 1950.Examples of use
