Triarylmethane dyes are synthetic organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s containing triphenylmethane

Triphenylmethane

Triphenylmethane, or triphenyl methane, is the hydrocarbon with the formula 3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane has the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display...

 backbones. As dyes, these compounds are intensely colored. Many of these dyes undergo reactions in response to acid and base, and thus serve as pH indicator

PH indicator

A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH of the solution can be determined visually. Hence a pH indicator is a chemical detector for hydronium ions or hydrogen ions in the Arrhenius model. Normally, the indicator causes the...

s.

As a consequence of their structure, the Friedel-Crafts alkylation reaction is a popular method to prepare many of these compounds:

Families

Some triarylmethane dyes can be grouped into families of dyes with very similar structures. In some cases, the anions associated with the cationic dyes (say crystal violet) vary even though the name of the dye does not.

Fuchsine dyes

Fuchsine dyes have amine functional groups at the p-positions of each phenyl group.

Bridged arenes

Where two of the aryl groups are bridged by a heteroatom, these triarylmethane compounds may be further categorized into acridine

Acridine

Acridine, C13H9N, is an organic compound and a nitrogen heterocycle. Acridine is also used to describe compounds containing the C13N tricycle....

s (nitrogen-bridged), xanthene

Xanthene

Xanthene is a yellow organic heterocyclic compound. Its chemical formula is 1310. It is soluble in diethyl ether. Its melting point is 101-102 °C and its boiling point is 310-312 °C...

s (oxygen-bridged), and thioxanthene

Thioxanthene

Thioxanthene is a chemical compound in which the oxygen atom in xanthene is replaced with a sulfur atom. It is also related to phenothiazine. Several of its derivatives are used as typical antipsychotics in the treatment of schizophrenia and other psychoses....

s (sulfur-bridged).