are synthetic organic compound
s containing triphenylmethane
backbones. As dye
s, these compounds are intensely colored. They are produced industrially as dyes.
Triarylmethane dyes can be grouped into families according to the nature of the substituents on the aryl groups. In some cases, the anion
s associated with the cationic dyes (say crystal violet) vary even though the name of the dye does not. Often it is shown as chloride.
Methyl violet dyes
Methyl violet dyes have dimethylamino groups at the p
-positions of two aryl groups.
Image:Methyl Violet 2B.png| Methyl violet
Image:Methyl Violet 6B.png| Methyl violet
Image:Methyl Violet 10B.png| Methyl violet 10B
Fuchsine dyes have primary or secondary amines (NH2 or NHMe) functional groups at the p
-positions of each aryl group.
File:Rosaniline hydrochloride.svg| Fuchsine
NewFuchsineStructure.png| New fuchsine
Fuchsine acid vector.svg| Fuchsine acid
Phenol dyes have hydroxyl groups at the p
positions of at least two aryl groups.
File:Phenol-red-zwitterionic-form-2D-skeletal.png| Phenol red
File:Chlorophenol red.png| Chlorophenol red
File:Structure of cresol red.png| Cresol red
File:Structure of Bromocresol purple.png| Bromocresol purple
File:Bromocresol green.png| Bromocresol green
Malachite green dyes
Malachite green dyes are related to the methyl violet dyes, except that they contain one phenyl (C6H5) group.
Image:Malachite green structure.svg | Malachite green
Image:Structure of the dye brilliant green.png| Brilliant green (dye)
Image:Brilliant Blue FCF(2).svg| Brilliant Blue FCF
, a common food colorant.
Victoria blue dyes
Victoria blue dyes are related to the methyl violet dyes, except they contain one naphthylamino group. Variation is found is dimethylamine vs diethylamino substituents on the phenyl rings and variations of the secondary amine on the naphthyl group.
File:Victoria blue B with charge.svg| Victoria Blue B
File:Victoria blue FBR revised.svg | Victoria Blue FBR
File:Victoria blue BO.svg| Victoria blue BO
File:Victoria pure blue FGA revised.svg| Victoria Blue FGA
File:Victoria blue 4 R revised.svg| Victoria blue 4 R
File:Victoria blue R revised.svg| Victoria blue R
Where two of the aryl groups are bridged by a heteroatom, these triarylmethane compounds may be further categorized into acridine
s (nitrogen-bridged), xanthene
s (oxygen-bridged), and thioxanthene
The amine-containing dyes are often prepared from Mischler's ketone
or its diethylamino analogue. In this way, the third aryl group is readily differentiated. The Friedel–Crafts alkylation
reaction is a popular method to prepare many of the phenolic derivatives:
In addition to their dominant use as dyes, many of these dyes react reversibly with acid and base, and thus serve as pH indicator