alizarin


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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 ?
Dual staining of corneal endothelium with trypan blue and alizarin red S: importance of pH for the dye-lake reaction.
13 We showed BMSCs could differentiate into osteoblast lineage secreting mineral matrix as one of the major components of bone matrix (calcium phosphate) detected by Alizarin red S staining as described before.
Based on the evidence of ALP staining, Dex-elicited decreased capacity of osteoblastic differentiation was blocked by KLF15 siRNA in the two cells (Figures 6(a) and 6(b)), as well as activity of bone formation measured by Alizarin Red S staining (Figure 6(c)).
The osteogenic capacity of the cells, as assessed by alizarin red staining of in vitro mineralization, was decreased in Pb-exposed mice but was not significantly changed with HFD (Figure 4B).
Mineralization in the induced osteoblasts was determined by Alizarin Red S staining as previously described (Li et al.
Alizarin red, calcein and tetracycline are commonly used PFCs in bone histomorphometry, appearing as red, green and bluish green respectively under the fluorescent microscope.
After 14 days, the cells were stained by Alizarin red-S and the red calcium deposits were visualized by microscopic examination.
Calcification will be visually observed using alizarin staining.
Thin sections were stained with alizarin red-s for differentiation of calcite and dolomite following Dickson [8].
The differentiated AMSCs were stained with Oil Red O for analysis of lipid droplet in adipogenic induction or Alizarin Red for calcium in osteogenic induction.