1,2,4-Trihydroxyanthraquinone, commonly called purpurin, is an

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic hydrocarbon, aromatic organic compound with formula . Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein th ...

. It is a naturally occurring red/yellow dye. It is formally derived from 9,10-

by replacement of three

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

atoms by

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

(OH) groups. Purpurin is also called verantin, smoke Brown G, hydroxylizaric acid, and C.I. 58205. It is a minor component of the classical

lake pigment A lake pigment is a pigment made by precipitating a dye with an chemically inert, inert binder (material), binder, or mordant, usually a metallic salt. Lake pigments are largely organic compound, chemically organic.K. Hunger. W. Herbst "Pigments, ...

"madder lake" or

Rose Madder Rose madder (also known as madder) is a red paint made from the pigment madder lake, a traditional lake pigment extracted from the common madder plant '' Rubia tinctorum''. Madder lake contains two organic red dyes: alizarin and purpur ...

History

Madder root has been used for dying cloth at least since 1500 BC.
Madder Root
'' catalog entry at Natural Pigments website. Accessed on 2010-01-22. Purpurin and alizarin were isolated from the root by Pierre Robiquet and

Colin Colin may refer to: * Colin (given name) * Colin (surname) * ''Colin'' (film), a 2008 Cannes film festival zombie movie * Colin (horse) (1905–1932), Thoroughbred racehorse * Colin (humpback whale), a humpback whale calf abandoned north of Sydney, ...

, two French chemists, in 1826. They were identified as anthracene derivatives by Gräbe and Liebermann in 1868. They also synthesized alizarin from bromoanthraquinone, which, together with the conversion of alizarin into purpurin published previously by M. F. De Lalande, provided the first synthetic route to purpurin. The positions of the OH groups were determined by

Bayer Bayer AG (English: , commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and is one of the largest pharmaceutical companies and biomedical companies in the world. Headquartered in Leverkusen, Bayer' ...

and

Caro Caro may refer to: Places * Caro, Michigan, United States * Caro, Morbihan, France * Çaro, Pyrénées-Atlantiques, France Other uses * Caro (given name), including a list of people with the given name * Caro (surname), including a list of peo ...

in 1874–1875.

Natural occurrence

Purpurin occurs in the roots of the

madder ''Rubia'' is the type genus of the Rubiaceae family of flowering plants, which also contains ''Coffea'' (coffee). It contains around 80 species of perennial scrambling or climbing herbs and subshrubs native to the Old World. The genus and it ...

plant (''

Rubia tinctorum ''Rubia tinctorum'', the rose madder or common madder or dyer's madder, is a herbaceous perennial plant species belonging to the bedstraw and coffee family Rubiaceae. Description The common madder can grow up to 1.5 m in height. The evergreen ...

''), together with

alizarin Alizarin (also known as 1,2-dihydroxyanthraquinone, Mordant Red 11, C.I. 58000, and Turkey Red) is an organic compound with formula that has been used throughout history as a red dye, principally for dyeing textile fabrics. Historically it wa ...

(1,2-dihydroxyanthraquinone). The root actually contains colorless

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s of the dyes.

Properties

Purpurin is a

crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...

solid, that forms orange-red needles melting at . It becomes red when dissolved in

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

, and yellow when dissolved with

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

s in boiling water. It is insoluble in

hexane Hexane () or ''n''-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14. Hexane is a colorless liquid, odorless when pure, and with a boiling point of approximately . It is widely used as ...

but soluble in

chloroform Chloroform, or trichloromethane (often abbreviated as TCM), is an organochloride with the formula and a common solvent. It is a volatile, colorless, sweet-smelling, dense liquid produced on a large scale as a precursor to refrigerants and po ...

, and can be obtained from chloroform as reddish needles. Unlike alizarin, purpurin is dissolved by boiling in a solution of

aluminium sulfate Aluminium sulfate is a salt with the chemical formula, formula . It is soluble in water and is mainly used as a Coagulation (water treatment), coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking ...

, from which it can be

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

d by acid. This procedure can be used to separate the two dyes.Irving Wetherbee Fay (1919) ''The chemistry of the coal-tar dyes''. Van Nostran
Online version
accessed on 2010-01-22. Like many dihydroxy- and trihydroxyanthraquinones, pupurin has a

purgative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

action, although only 1/20 as effective as 1,2,7-trihydroxyanthraquinone (anthrapurpurin).Alister McGuigan, Hugh (1921
''An introduction to chemical pharmacology; pharmacodynamics in relation to chemistry''
P. Blakiston's son, Philadelphia.

Uses

Purpurin is a fast dye for

cotton Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...

printing and forms complexes with various metal ions. It fades faster than alizarin on exposure to sunlight. A study published in ''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'' journal ''Scientific Reports'' suggests that the purpurin could replace cobalt in

lithium-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. Li-ion batteries are characterized by higher specific energy, energy ...

. Eliminating cobalt would mean eliminating a hazardous material, allow batteries to be produced at room temperature, and lower the cost of recycling batteries. Extracting purpurin from farmed

is a simple task; alternately, the chemical could be synthesized in a lab.

References

{{DEFAULTSORT:Trihydroxyanthraquinone, 1, 2, 4- Anthraquinone dyes Hydroxyquinols Trihydroxyanthraquinones

History

Natural occurrence

Properties

Uses

See also

References