Of alizarin

Anlhraquinone-2-su phonic acid. The sodium salt, commonly called silver salt , is used for the preparation of alizarin and 2-aminoanthraquinone and to prepare Fieser s solution. Aminoanthraquinone derivatives are the basis of many dyestuffs. 

Addition of ammonium hydroxide to an aluminium salt in solution in presence of alizarin, gives a pink precipitate. 

The way a synthesis is planned has changed substantially over time. Until the beginning of the 20th century many noteworthy syntheses had been developed, c.g., of alizarin (C. Gracbc, C, Licbermann, 1869) and indigo (A, Bacycr, 1878). 

Subsequendy, H. Caro and W. H. Perkin independendy developed the commercial manufacturing process of alizarin from anthraquinone (qv) through anthraquinone-2-sulfonic acid. Taking advantage of these inventions, many manufacturers came to produce various kinds of hydroxyanthraquinones, which were used as mordant dyes for dyeing cotton and wool. 

Mordant dyes have hydroxy groups in their molecular stmcture that are capable of forming complexes with metals. Although a variety of metals such as iron, copper, aluminum, and cobalt have been used, chromium is most preferable as a mordant. Alizarin or Cl Mordant Red 11 [72 8-0] (1) (Cl 58000), the principal component of the natural dye obtained from madder root, is the most typical mordant dye (see Dyes, natural). The aluminum mordant of alizarin is a well-known dye by the name of Turkey Red and was used to dye cotton and wool with excellent fastness. However, as is the case with many other mordant dyes, it gave way to the vat or the azoic dyes, which are applied by much simpler dyeing procedures. 

Purpurin [81-54-9] (179) is a usefiil iatemiediate for preparing acid-mordant dyes, and is prepared by oxidation of alizarin with manganese dioxide and sulfuric acid (145). 

Spray solution A 0.25% [3] or saturated solution of alizarin [4] in ethanol. 

Ri actio) .—Make a small ciuantity of solution of alizarin m austic soda, and pom into a beaker containing a strong solution ot alum. Ihe insoluble aluminium alizarate is piecipitated as a led lake. See Appendix p 316. 

Alizarin.—The fiist synthesis of alizarin is due to C.raebe and Liebennann (i868). The present method was discoi eiecl simultaneously by these chemists and by Peikm. By the aqtion... 

Statistical evaluation of HPLC UV MS[19] and CE UV MS[20] methods proves that MS detection of anthraquinone dyes is more sensitive than UV, especially in the case of chromatographic analysis of laccaic acids (almost 20 times) and purpurin (almost 40 times). However, detection limits of HPLC ESI MS determination of alizarin and purpurin (0.03 gg ml ) are about 20 times lower than those of CE ESI MS (0.52 0.58 gg ml x). 

G.C.H. Derksen, G.P. Lelyveld, T.A. van Beek, A. Capelle and JE. Groot, Two validated HPLC methods for the quantification of alizarin and other anthraquinones in Rubia tinctorum cultivars, Phytochem. Anal., 15, 397 406 (2004). 

In another procedure [522] the sample of seawater (0.5-3 litres) is filtered through a membrane-filter (pore size 0.7 xm) which is then wet-ashed. The nickel is separated from the resulting solution by extraction as the dimethylglyoxime complex and is then determined by its catalysis of the reaction of Tiron and diphenylcarbazone with hydrogen peroxide, with spectrophotometric measurement at 413 nm. Cobalt is first separated as the 2-nitroso-1-naphthol complex, and is determined by its catalysis of the oxidation of alizarin by hydrogen peroxide at pH 12.4. Sensitivities are 0.8 xg/l (nickel) and 0.04 xg/l (cobalt). 

Lower pH did not give good yields. The pH was checked by means of filter paper, which had been dipped in an alcoholic solution of alizarin and then dried. 

The synthesis of indigo was much more difficult than that of alizarin (6.2) [43]. In 1865 von Baeyer first attempted to obtain indigo by reductive dimerisation of isatin (6.116) he finally achieved a seven-step synthesis from phenylglycine via isatin in 1878. Many syntheses have been developed subsequently for indigo, but very few of these have achieved industrial importance. 

A similar behaviour is observed in the case of the phenolsulphonic acids and in particular in that of anthraquinone, which, in its substitution reactions, is extraordinarily like naphthalene. Anthraquinone is sulphonated with more difficulty than is naphthalene, and in consequence the conditions of increased temperature which must be applied bring about the formation of the /8-acid, the important starting point for the synthesis of alizarin. In industrial practice, however, ways and means have been found for producing also anthraquinone-a-sulphonic acid, which was formerly not readily obtainable. a-Substitution takes place when the sulphonation is catalysed by mercury1 (R. E. Schmidt). 

For purification the crude product is boiled with glacial acetic acid (preferably in the extraction apparatus shown in Fig. 27). Fine red needles melting point 289°. Sublimation in a vacuum from a sausage flask is also to be recommended the sausage should be fixed low down and the bulb completely immersed in a nitrate bath (equal parts of potassium and sodium nitrates). Much poorer yields of alizarin are obtained by using an open round-bottomed flask at 189°-190°. 

Uses Dyes starting material for the preparation of alizarin, phenanthrene, carbazole, 9,10-anthraquinone, 9,10-dihydroanthracene, and insecticides in calico printing as component of smoke screens scintillation counter crystals organic semiconductor research wood preservative. 

This strategy is illustrated in Figs. 2.21 and 2.22 for the case of alizarin. The parent dye exhibits two main peaks at +0.40 and -0.60 V, corresponding respectively to the oxidation of the o-phenol moiety and the reduction of the quinone group. After application of a reduction step at -1.50 V, the resulting polyhydroxy species produces overlapping oxidation signals at +0.5 and -0.07 V. 

Data in Table 4.1 correspond, respectively, to standard additions of alizarin and purpurin to a mixture of alizarin (5.14%) and purpurin (5.32%) upon addition of morin (4.95%) as an auxiliary reference compound using silica as solid diluent in contact with the acetate buffer. Currents i and ii were measured at the above-mentioned potentials, while ip (R) was measured as the peak current of the morin-centered peak. 

With hydrous zinc oxide there is a slight adsorption of yellow alizarinic acid and purple sodium alizarate. A variation in the degree of acidity with stannic oxide and zinc oxide will give all variations of color between yellow and purple, while the presence of alumina introduces a red. This accounts for the fact of alizarin being what is called a polygenetic color, because the color varies with the nature of the mordant. Other examples of this class are said to be cochineal and logwood but we have not yet studied these dyes. 

The general conclusions of this paper are as follows 1. An alcohohc solution of alizarinic acid added to alumina gives a pink lake, showing the adsorption of the red alizarin anion. 

By changing the mordant and the acidity the color of alizarin lakes can be made to vary from purple to red to yellow with a colorless mordant. This explains why alizarin is called a polygenetic dye. 

Later, at BASF, a process was developed for the manufacture of alizarin by the caustic fusion of anthraquinone-2-sulfonic acid (so-called silver salt) which was patented in England on the 25th of June, 1869. One day later, W. Perkin applied for a patent for the manufacture of alizarin by a process almost identical to the German process except that the silver salt was prepared as follows ... 

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