Alizarin systems

Quinones that are based on the anthracene ring system are called anthraqumones Alizarin is one example of an anthraqumone dye... 

The conjugated chromophore (color-causing) system can be extended by electron-donor groups such as —NH2 and —OH and by electron-acceptor groups such as —NO2 and —COOH, often used at opposite ends of the molecule. An example is the aromatic compound alizarin [72-48-0], also known since antiquity as the ted dye madder. 

There is a wide diversity of chemical structures of anthraquinone colorants. Many anthraquinone dyes are found in nature, perhaps the best known being alizarin, 1,2-dihydroxyanthraquinone, the principal constituent of madder (see Chapter 1). These natural anthraquinone dyes are no longer of significant commercial importance. Many of the current commercial range of synthetic anthraquinone dyes are simply substituted derivatives of the anthraquinone system. For example, a number of the most important red and blue disperse dyes for application to polyester fibres are simple non-ionic anthraquinone molecules, containing substituents such as amino, hydroxy and methoxy, and a number of sul-fonated derivatives are commonly used as acid dyes for wool. 

In a bidentate ligand system, three molecules of a dye containing either a terminal salicylic acid unit (as in 5.2) or an o-nitrosonaphthol residue are able to chelate simultaneously with a trivalent metal ion of CN6, such as chromium (III) or iron(III), to form a 1 3 metal-dye complex (as in 5.8). Historically, the most important bidentate ligand system was alizarin (5.1). It has been suggested that both hydroxy groups and the keto group in the peri position are all involved with the metal atom in the chelation mechanism. 

Numerous experimental systems verified the theory of surface electrode reactions. Reductions of methylene blue [92], azobenzene [79, 82] alizarine red S [93], probucol [94], molybdenum(V)-fulvic acid complex [95], molybdeniun(VI)-1,10 phenanthroline-fulvic acid complex [96], indigo [97], and reduction of vana-dium(V) [98] at a mercury electrode are some of the examples for surface electrode... 

Morinda citrifolia L. M. officinalis L. Je Shu Ba Ji Tian (root) Dihydroxy methyl anthraquinone, glucoside morindin, rubichloric acid, alizarin, alpha-methyl ether, rubiadin-I-methyl ether, tannins, morindadiol, masperuloside, soranjudiol, nordamnacanthal.50-424 Treat beri-beri, cancer, lumbago, cholecystitis, increase leukocyte count, stimulate endocrine system. 

The use of herbal medicines prepared from the root of Rubia tinctorum (madder) is no longer permitted in Germany. Root extracts have shown genotoxic effects in several test systems, which are attributed to the presence of the anthraquinone derivative lucidin. One of the other main components, alizarin primeveroside, is transformed into 1-hydroxyanthraquinone when given orally to the rat, in which this metabolite has carcinogenic activity (6). 

The competing ligand system alizarin-3-sulphonic acid-OH" has been used to determine formation constants of mononuclear hydroxo-complexes of Ga at 25 °C, and the hydrolysis constants of gallium ions at I = 0.1—l.O.519... 

Numerous methods for determining fluoride are based on compounds of thorium with organic reagents, such as Alizarin S [55], Xylenol Orange [48], Arsenazo I [4], and chloranilic acid [56]. An exceptionally sensitive method is based on the ternary system Th-Chrome Azurol S-CTA (e= 1.0-10 at 635 nm) [57]. 

Fluoride Drainage water from water treatment plant Distillation UV—Vis 0.05—15 mg L 1 Flow injection system sulphuric and phosphoric acids for sample acidification determination relies on the La(III)—fluoride—alizarin complex. [311]... 

Although alizarin-S (l,2-dihydroxyanthraquinone-3-sulfonate) has been used (162) for many years for the detection and estimation of zirconium and hafnium, the composition of the product formed in this system is still uncertain. Eecent studies on hafnium (43) and zirconium (317, 419) complex formation by spectrophotometric methods led to the conclusion that the zirconium 1 1 complex exists in the pH range 1.0-1.8 at a metal concentration of 1 x 10 M. Below that pH no complex could be observed and above that pH only suspensions were obtained. Hafnium, on the other hand, is said to form the 1 2 ligand complex at metal ion concentrations of (2 to 4) x 10 mole/liter over the pH range 1.0 to 4.0. A stability constant of 10.3 0.3 was reported for this species. The 1 1 complex of zirconium is extractable with i-butanol (149a). 

The colourant principle of cochineal is carminic acid (30) which is used as carmine in the form of its aluminium and other metallic chelates (calcium-aluminium) in much the same way that alizarin was formerly employed as a mordant dye by chelation of the 1,2-dihydroxy system. 

The antioxidant activity of alizarin was established in four different assays (1) suppression of light emission in the p-iodophenol enhanced chemiluminescent assay, (2) scavenging of superoxide anion (02 -) in a hypoxanthine-xanthine oxidase system, (3) protection of rat liver microsomes from lipid peroxidation by ADP/iron(II) ions, and (4) protection of bromobenzene-intoxicated mice from liver injury in vivo [141]. Alizarin was compared with Trolox (water soluble vitamin E), the flavonoid baicalin and green tea proanthocyanidins. In assay (1) the activity of alizarin was 76% of that of Trolox. In assay (2) the inhibition of 02 -induced chemiluminescence was 40%, 32%, 23% and 14% for Trolox, alizarin, green tea polyphenols and baicalin respectively. Alizarin was not significantly active in the lipid peroxidation assay but after baicalin the most active compound in the in vivo assay. This shows again the difficulty in the evaluation of antioxidant activity and the differences between in vitro and in vivo assays [141]. 

Okabayashi et al.[29] rep)orted on a dual preconcentration column system for the determination of low concentrations of fluoride using a fluoride electrode. 1 ml of sample was sorbed selectively on an anion-exchanger loaded with alizarin fluorine blue sulphonate-lanthanum complex. The columns were loaded alternately, and successively eluted with IM sodium chloride - O.S M sodium chloride. A detection limit of 1 /xg r was achieved at a sampling frequency of 24 h ... 

Leon-Gonzalez et al.[31] proposed an FI spectrophotometric method for the determination of Triton-type non-ionic surfactants based on their reaction with alizarin fluorine blue. An on-line ion-exchange column was incorporated in the system to eliminate interferences from ionic and amphoteric surfactants. In case of interferences from non-ionic surfactants, an on-line Amberlite XAD-4 adsorption column was used to retain selectively the Triton-type surfactant, which was subsequently eluted by ethanol. However, no information was given regarding interferences from refractive index effects at the ethanol/aqueous interface and their elimination. 

---