Triarylmethane dye
The base for the group of triphenylmethane dyes is the triphenylmethane. At least two of the aromatic rings bear (so-called Auxochromes ) electron-donating substituents. Triphenylmethane dyes are mainly used in printing technology or ( due to their low acid resistance ) as indicators of application, as well as textile and food dyes. They are not very lightfast in general.
Groups of substances
Aminotriphenylmethanfarbstoffe
The representatives of this group are characterized by at least two amino groups from as Auxochromes.
- Parafuchsine
- Crystal violet
- Malachite green
- Methyl green
- Aluminon
Derivatives with sulfonic acid group:
- Acid fuchsin
- Brilliant Blue FCF
- Patent Blue V
- Water blue
Hydroxytriphenylmethanfarbstoffe
The compounds of this subgroup contain at least one hydroxyl group as auxochrome.
- Fuchsone ( Diphenylchinomethan ) in this case represents the parent compound, but it still has no dye character.
- Benzaurin (p- Hydroxyfuchson ) is a Phenolabkömmling, is yellowish red and has acidic properties. With dilute alkalis arise violet salts.
- Aurin (p, p'- Dihydroxyfuchson ) dissolves in alkalies with a red color and is used as a pH indicator.
Phthaleins and sulfonphthaleins
This class of dyes derived from the o- carboxylic acid of Triphenylmethanols. The display is carried out by heating one equivalent of phthalic anhydride with 2 equivalents of the phenol component ( in the presence of low amounts of concentrated sulfuric acid). Showing the sulfonphthaleins the o - sulphobenzoic anhydride is reacted with the phenolic component. Phenolphthalein forms the basis of the connection phthaleins and is one of the best known indicators. Analogously, the phenol forms the basis of the connection sulfonphthaleins.
Almost all of the dyes are used as indicators. If, as a phenol component, resorcinol, pyrogallol, and 2,6- dihydroxytoluene, then also forms an ether linkage (for example, fluorescein, eosin, calcein ). As abzuleitendes backbone here is also the xanthene to look at.