Triarylcarbonium pigments

There are two groups of triarylcarbonium pigments inner salts of triphenyl-methane sulfonic acids, and complex salts with heteropolyacids containing phosphorus, tungsten, molybdenum, silicon, or iron. 

---

For reasons of molecular symmetry, only the carbonium structure is used in this book to describe triarylcarbonium pigments. 

Two types of insoluble triarylcarbonium compounds are used industrially as pigments. Both are salts of these basic dyes. So-called Alkali Blue type triarylcarbonium pigments are inner salts of sulfonic acids, while the second group comprises salts of complex inorganic anions of heteropolyacids. 

It should be mentioned that all triarylcarbonium pigments are described by structures which are no more than a useful approximation of reality. These products in actual fact represent mixtures of various compounds which are obtained through an intricate reaction pattern, the respective written structure being the main component. 

The list of significant Alkali Blue type triarylcarbonium pigments includes compounds which are derived from diarylated and triarylated rosanilines. Table 33 shows triarylcarbonium pigments which are listed in the Colour Index. 

---