Toluidine red is an
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with the formula . A dark red solid, the compound is classified as a
azo dye
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C l ...
consisting of a
2-naphthol
2-Naphthol, or β-naphthol, is a fluorescent colorless (or occasionally yellow) crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are ...
group
linked to a 2-nitro-4-methylphenyl substituent. Toluidine red is a traditional
pigment
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
, found in
oil paint
Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. Oil paint also has practical advantages over other paints, mainly because it is waterproof.
The earliest surviving ...
s. Although once popular, it suffers as a pigment owing to "insufficient lightfastness and bleeding when incorporated into a paint system."
Safety
It is classified as
carcinogenic
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and Biological agent, biologic agent ...
, a property that it shares with many
azo dye
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C l ...
s.
[{{cite journal , doi=10.1016/s1383-5742(99)00090-3 , title=Genotoxic hazards of azo pigments and other colorants related to 1-phenylazo-2-hydroxynaphthalene , date=2000 , last1=Møller , first1=Peter , last2=Wallin , first2=Håkan , journal=Mutation Research/Reviews in Mutation Research , volume=462 , issue=1 , pages=13–30 , pmid=10648921 ]
References
Organic pigments
Shades of red
2-Naphthols
Nitrotoluene derivatives
Azo compounds