ABSTRACT
This chapter uses the traditional terms di- and triarylmethane dyes. More chemically precise wordings such as di- and triarylmethine dyes have been proposed, as noted by Zollinger. False expectations may arise with dyes such as acid and basic fuchsines; and alkali, aniline and methyl blues. The dye sold under this name is in fact ethyl green; this is sometimes noted on labels or in catalogs, but rarely if ever in the literature. In Michler’s hydrol the donor groups are tertiary amino groups; in others amino di- and triarylmethanes, including many dyes, the donor group may be a primary or secondary amino moiety. Many of the amino di- and triarylmethane cations, whether or not they can lose a proton in this way, can slowly combine covalently with hydroxide ions. The nonionic products, known as pseudobases or carbinols, are more lipophilic than their ionic parent compounds.
