Other 6,13-Disubstituted Quinacridones

It is noteworthy that the dichloro derivative 47 is a colorless compound (s ax 295 run) in contrast to 2,5-dianilinoterephthalic acid 17, (R = H) which is colored (Smax 435 run). Evidently the hexasubstituted central benzene ring of 47 prevents a coplanar arrangement and consequently an effective electronic interaction between the aniBno and carboxy groups. Cyclization of the terephthalic acid in PPA 

The Chapman rearrangement also has been applied to the synthesis of the parent quinacridone as well as other derivatives not readily accessible by other methods. However, this synthesis is mostly of theoretical interest and at present has no manufacturing utility. 

The phenomenon of solid solution formation has been known for some time in the copper phthalocyanine series of pigments. For example, partially chlorinated copper phthalocyanine is in effect a solid solution of the parent compound and 

QAQ is a yellow compound with deficient lightfastness, but by virtue of solid solution formation with quinacridone the resulting maroon pigment demonstrates outstanding photochemical stability. Evidently, the energy of the excited 

One blue-shade red product from this group has been commercialized for use in automotive metallic finishes (PV 42, CAS 71819-79-9) [54]. 

---