1,2,4-Trihydroxyanthraquinone, commonly called purpurin, is an
anthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...
. It is a
naturally occurring red/yellow dye. It is formally derived from 9,10-
anthraquinone
Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...
by replacement of three
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
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 hydro ...
(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 inert binder, or mordant, usually a metallic salt. Unlike vermilion, ultramarine, and other pigments made from ground minerals, lake pigments are organic.K. Hunger. W. Herbst "Pi ...
"madder lake" or
Rose Madder.
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
Pierre Jean Robiquet (13 January 1780 – 29 April 1840) was a French chemist. He laid founding work in identifying amino acids, the fundamental building blocks of proteins. He did this through recognizing the first of them, asparagine, in 1806 ...
and
Colin, 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 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 coffee. It contains around 80 species of perennial scrambling or climbing herbs and subshrubs native to the Old World. The genus and its best-known ...
plant (''
Rubia tinctorum''), 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 prominent red dye, principally for dyeing textile fabrics. Historic ...
(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 glycoside ...
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, macros ...
solid, that forms orange needles melting at , but becomes red when dissolved in
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
, and yellow when dissolved with
alkalis in boiling water. It is insoluble in
hexane
Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14.
It is a colorless liquid, odorless when pure, and with boiling points approximately . It is widely used as a cheap, relatively ...
but soluble in
chloroform, and can be obtained from chloroform as reddish needles.
Unlike alizarin, purpurin is dissolved by boiling in a solution of
aluminum sulfate
Aluminium sulfate is a salt with the formula Al2 (SO4)3. It is soluble in water and is mainly used as a coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking water and wastewater treatment plan ...
, from which it can be
precipitate
In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...
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
(anthrapurpurin).
[
Hugh Alister McGuigan (1921), ''An introduction to chemical pharmacology; pharmacodynamics in relation to chemistry''. P. Blakiston's son, Philadelphia]
Online version
at archive.org, accessed on 2010-01-30.
Uses
Purpurin is a fast dye for
cotton
Cotton 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 cellulose, and can contain minor pe ...
printing and forms complexes with various metal ions. However it fades faster than alizarin on exposure to sunlight.
[
A study published in '']Nature
Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' journal ''Scientific Reports'' suggests that the purpurin could replace cobalt in lithium-ion batteries. 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 madder
''Rubia'' is the type genus of the Rubiaceae family of flowering plants, which also contains coffee. It contains around 80 species of perennial scrambling or climbing herbs and subshrubs native to the Old World. The genus and its best-known ...
is a simple task; alternately, the chemical could be synthesized in a lab.
See also
* Trihydroxyanthraquinone A trihydroxyanthraquinone or trihydroxyanthracenedione is any of several isomeric organic compounds with formula , formally derived from anthraquinone by replacing three hydrogen atoms by hydroxyl groups. They include several historically importan ...
* Pierre Robiquet
Pierre Jean Robiquet (13 January 1780 – 29 April 1840) was a French chemist. He laid founding work in identifying amino acids, the fundamental building blocks of proteins. He did this through recognizing the first of them, asparagine, in 1806 ...
, discoverer of purpurin in 1826
*
References
{{DEFAULTSORT:Trihydroxyanthraquinone, 1, 2, 4-
Anthraquinone dyes
Hydroxyquinols
Trihydroxyanthraquinones