alizarin


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Related to alizarin: alizarin red, alizarin yellow, alizarin red S

alizarin

(əlĭz`ərĭn), or 1,2-dihydroxyanthraquinone, mordant vegetable dye obtained originally from the root of the madder plant (Rubia tinctorum), in which it occurs as a glucoside. The term also includes a group of synthetic dyestuffs prepared from coal-tar derivatives. A method for the synthesis of alizarin was first discovered (1868) by Karl Graebe and Karl Liebermann, German chemists. With salts of metals the compound forms brilliant lakeslake,
in dyeing, an insoluble pigment formed by the reaction between an organic dye and a mordant. The color of a lake depends upon the mordant as well as the dye used. Generally, lakes are not as colorfast as many inorganic dyes, but their colors are more brilliant.
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, although by itself it is a poor dye. Turkey red is produced with an aluminum mordant, other shades of red with calcium and tin salts, dark violet with iron mordants, and brownish red with chromium. Purpurin, also used in dyeing, occurs with alizarin in madder and is produced synthetically.

Alizarin

 

a dye in the form of orange crystals slightly soluble in water and readily soluble in aqueous alkalis; its melting point is 289°C.

Alizarin is found in the roots of the madder plant (Rubia tinctorum), extracts of which were used for dyeing as long ago as ancient times in Egypt, Persia, and India. Known as alizari, madder roots were imported to Europe from Eastern countries. Beginning with the second half of the 18th century, the madder was cultivated in the Crimea and the Caucasus. The dye was first obtained from the plant in 1826 by the French chemists P. Robiquet and J. Colin. Later, in 1869, the German chemists K. Graebe and K. T. Lieber-mann deduced the structure of alizarin and synthesized it for the first time. Cultivation of the madder came to an end when synthetic alizarin became cheaper than the natural product. Synthetic alizarin began to be produced in Russia in 1874 (in the city of Kirzhach).

Alizarin belongs to the class of mordant anthraquinone dyes. With the salts of certain polyvalent metals, alizarin forms colored complex compounds, the so-called lakes, which bond firmly with textile fibers. The most widely used compound of alizarin with aluminum is of bright red color; with iron, of violet color; and with chromium, of brown color.

Alizarin is scarcely used any longer as a textile dye, since it is inferior in quality to many other dyes and more expensive as well. However, it is used as an intermediate product in the synthesis of other dyes; for example, aluminum madder lake is used in the preparation of paints for artists, as well as in polygraphy.

R. R. GALLE

alizarin

[ə′liz·ə·rən]
(organic chemistry)
C14H6O2(OH)2 An orange crystalline compound, insoluble in cold water; made synthetically from anthraquinone; used in the manufacture of dyes and red pigments.
References in periodicals archive ?
Procurement of insurance services for the control of the Institute Group alizarin and public health establishment Saint-Antoine (84).
Mineralization in the induced osteoblasts was determined by Alizarin Red S staining as previously described (Li et al.
5% Oil Red O (adipogenic differentiation) or 40 mM Alizarin Red S (osteogenic differentiation).
Following alizarin red staining, the stain for bone nodule formation was positive, as indicated by the red mineralized areas of the culture (Fig.
The actual chemical responsible for the colour was eventually determined to be a compound known as alizarin.
org/ alizarin 65 soixante-cinq relaxation OED online (see techniques "relaxation") 66 soixante-six exponential A mathematical expression expression consisting of a constant (especially e) raised to some power.
Unfortunately, the main carbonate minerals could not be differentiated during optical microscope examinations because the thin sections investigated were not stained with alizarin or any other relevant chemical.
Alizarin red S stains calcium specifically, reacting with calcium phosphate at pH 7 and pH 4.
A quotation taken from one of the diary extracts, printed in alizarin crimson vinyl lettering and mounted onto the wall adjacent to the framed set of prints, forms the third component (Figure 8).
So, Quinn darkened the snow with a mixture of ultramarine, yellow ochre, and alizarin crimson pigments.
Prior to the experiments, clams were maintained in 50 ppm seawater solution of alizarin red for 2 days to stain the shell surface for later reidentification (Hidu and Hanks 1968, Tanaka 1980).
The composition comprises at least one natural dye chosen from orceins, alizarin, purpurin, carminic acid, kermesic acid, purpuroqallin, protocatechaldehyde, indigo, curcumin, spinulosin, apiqenidin, chlorophyllin, sorghum, and cochineal carmine and at least one organic solvent.