Selected Anthraquinones

Anthraqrclines without substituents in ring A are rare and not more than ten are known. 4-Deoxyauramycinone (25a) was isolated from Streptomyces galilaeus in 1983 [27,28] and re-isolated from a marine-derived Streptomyces strain [29]. Antibiotic and antitumor activities were reported, although the biological activities of the aglycones are usually neghgible. 

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Solubility data of the dyestuffs are of interest for the optimization of this particular dyeing technique. Therefore an apparatus was developed for the determination of the solubilities in supercritical solvents at temperatures from 250 to 500 K and pressures up to 250 MPa according to the static analytical method [6, 7]. In particular, investigations on the solubility of some selected anthraquinone dyes in supercritical C02 and N20 and more recently of P-carotene in supercritical C02 and CC1F, were performed as a function of temperature and pressure (see section 4.). For the l,4-bis-(n-alkylamino)-9,10-anthraquinones the alkyl chains were systematically varied in the homologous series in order to study the effects of molecular size and polarity on the solubility phenomena [6-10]. 

AQ acts as the oxygen carrier and is present at 10 to 20% w/w. The selected anthraquinone must have the appropriate solubility profile in the quinone and hydroquinone form and should be resistant to oxidation by H2O2. 

With the exceptions of 1,4-benzoquiaone and 9,10-anthraquiaone, quiaones are not produced on a large scale, but a few of these are commercially available (see Anthraquinone). The 1995 prices of selected quiaones are Hsted ia Table 4. Most of the compouads are prepared by the methods described hereia. The few large-scale preparatioas iavolve oxidatioa of aniline, pheaol, or aminonaphthols, eg (110), from which (8) is obtaiaed ia 93% yield. 

The strength of electron-donor groups iacrease ia the order OH < NH < NHR < HNAr. Tetra-substituted anthraquiaones (1,4,5,8-) are more bathochromic than di- (1,4") 01 trisubstituted (1,2,4-) anthraquiaones. Thus, by an appropriate selection of donor groups and substitution patterns, a wide variety of colors can be achieved (see Dyes, anthraquinone). 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

The main by-products of the Ullmaim condensation are l-aniinoanthraquinone-2-sulfonic acid and l-amino-4-hydroxyanthraquinone-2-sulfonic acid. The choice of copper catalyst affects the selectivity of these by-products. Generally, metal copper powder or copper(I) salt catalyst has a greater reactivity than copper(Il) salts. However, they are likely to yield the reduced product (l-aniinoanthraquinone-2-sulfonic acid). The reaction mechanism has not been estabUshed. It is very difficult to clarify which oxidation state of copper functions as catalyst, since this reaction involves fast redox equiUbria where anthraquinone derivatives and copper compounds are concerned. Some evidence indicates that the catalyst is probably a copper(I) compound (28,29). 

In order to develop the dyes for these fields, characteristics of known dyes have been re-examined, and some anthraquinone dyes have been found usable. One example of use is in thermal-transfer recording where the sublimation properties of disperse dyes are appHed. Anthraquinone compounds have also been found to be usehil dichroic dyes for guest-host Hquid crystal displays when the substituents are properly selected to have high order parameters. These dichroic dyes can be used for polarizer films of LCD systems as well. Anthraquinone derivatives that absorb in the near-infrared region have also been discovered, which may be appHcable in semiconductor laser recording. 

Two large studies were done (250,251) for the selection of a2o, nitro, and anthraquinone dyes for carcinogen bioassay. Based on previous information or testing, a total of 30 dyes were selected based on chemical stmcture, potential exposure, and suspicion of carcinogenicity. 

Anthraquinone, 1-hydroxy-calcium aluminum chelate compound, 1,2 metal complexes dyes, 6,86 Antiarthritis drugs labelled gold compounds, 6, 969 metal complexes, 6,758 Antibiotic M139163,2, 974 Antibiotics ionophoric, 6, 553 metal complexes selective binding, 6, 552... 

It is anticipated that the new, environmentally friendly technology designed by Headwaters for H2O2 production will soon replace the current anthraquinone process because of the high activity, selectivity, and durability of the novel nanocatalyst. 

Olah et al. (1999) have been able to realize selective cyclisation of o-benzoyl benzoic acid to anthraquinone using dichlorobenzene as a solvent and Nafion-H as a catalyst. This may lead to avoidance of the Friedel-Crafts reaction using a stoichiometric amount of aluminium chloride and resulting in a lot of wa,ste. Many other examples of similar reactions have been reported. 

The anthraquinone group of the UAQ sensitizer is intercalated on the 3 -side of its linkage site [15]. Use of UAQ permits assessment of the directionality of long-range radical cation migration. Both AQ and UAQ enable the selective and efficient introduction of a radical cation in duplex DNA, whose lifetime is controlled by its relatively slow bimolecular reaction primarily with H20. 

Atmospheric ozone has also been reported as causing fading of certain dyes in some countries [425,426] diallyl phthalate (10.182) used as a carrier in the dyeing of cellulose triacetate fibres, is said to be an effective ozone inhibitor [427]. Nylon, especially when dyed with certain amino-substituted anthraquinone blue acid dyes, can also be susceptible to ozone fading [428,429]. Selection of ozone-resistant dyes is obviously the best counteractive measure, although hindered phenols (10.161) and hindered amines (10.162) are said to provide some protection. 

In pulp and paper processing, anthraquinone (AQ) accelerates the delignification of wood and improves liquor selectivity. The kinetics of the liquid-phase oxidation of anthracene (AN) to AQ with NO2 in acetic acid as solvent has been studied by Rodriguez and Tijero (1989) in a semibatch reactor (batch with respect to the liquid phase), under conditions such that the kinetics of the overall gas-liquid process is controlled by the rate of the liquid-phase reaction. This reaction proceeds through the formation of the intermediate compound anthrone (ANT) ... 

Catalytic amounts of this addend (4 equiv relative to Cu) increase the selectivity of the allylic oxidation when TBHP is used as the oxidant. No change was observed with terf-butyl perbenzoate. This observation suggests a dichotomy in the mechanism of this reaction when using the two oxidants. Furthermore, in the absence of anthraquinone, a small negative nonlinear effect (78) is observed while in its presence, a small positive nonlinear effect appears. The reasons for this reversal are not clear, although the authors observed that low enantiopurity catalysts lead to turbid... 

The application range designated by this generic name in the Colour Index incorporates those acid, direct and mordant dyes with substantivity for leather and satisfactory fastness on that substrate [55]. It is a commercially important sector, the number of products listed being exceeded only by the complete acid or direct dye ranges. As expected from the sources of this selection, about 85% of leather dyes are azo compounds (35% disazo, 30% monoazo, 20% metal-complex monoazo) and the remainder are mainly yellow to orange stilbene dyes and anthraquinone or triarylmethane types in the violet to green sectors. 

The new Colour Index volume Pigments and Solvent Dyes lists some 350 solvent dyes and gives their chemical structures, unlike earlier editions which named 800 dyes but included few structures. This fall in numbers is not because of any decreased use but rather the general contraction in numbers of all dyes used in the textile industry. Solvent dyes have been introduced not by attempts to synthesise new colorants but by selection and in some cases modification of known disperse dyes to meet the technical requirements. The majority of solvent dyes are azo compounds but among the blue dyes there are anthraquinones. The aqueous solubility of some of the parent sulphonated dyes has been reduced to acceptable levels by formation of their salts with heavy metals or long-chain alkylamines. 

The selectivity was enhanced by adding small amounts of anthraquinone-2-sulfonate (A2S), which decreased the formation of deoxy by-products. Thus, by adding 260 ppm of A2S with respect to arabinonic acid the selectivity to deoxy-products decreased from 4.2 to 1.6%. A2S acted as a permanent surface modifier since the catalyst was recycled with the same selectivity without further addition of A2S. The highest selectivity to arabitol was 98.9% at 98% conversion, with a reaction rate of 73 mmol h 1 gRU 1 at 80 °C. 

Lithium aluminum hydride reduced p-benzoquinone to hydroquinone (yield 70%) [576] and anthraquinone to anthrahydroquinone in 95% yield [576]. Tin reduced p-benzoquinone to hydroquinone in 88% yield [174] Procedure 35, p. 214). Stannous chloride converted tetrahydroxy-p-benzoquinone to hexa-hydroxybenzene in 70-77% yield [929], and 1,4-naphthoquinone to 1,4-di-hydroxynaphthalene in 96% yield [180]. Other reagents suitable for reduction of quinones are titanium trichloride [930], chromous chloride [187], hydrogen sulfide [248], sulfur dioxide [250] and others. Yields are usually good to excellent. Some of the reagents reduce the quinones selectively in the presence of other reducible functions. Thus hydrogen sulfide converted 2,7-dinitro-phenanthrene quinone to 9,10-dihydroxy-2,7-dinitrophenanthrene in 90% yield [248]. 

Further evaluation of SeaKleen and other water-soluble derivatives of 9,10-anthraquinone for use as selective algicides in catfish aquaculture will require additional research such as determining the environmental fate of these quinone-based algicides and whether there is any potential accumulation in the flesh of channel catfish. In addition, studies required by the USEPA for the consideration of the approval of quinone-based algicides in food-fish production ponds will require at least several more years. 

Schrader KK, Nanayakkara NPD, Tucker CS, Rimando AM, Ganzera M, Schaneberg BT, Novel derivatives of 9,10-anthraquinone are selective algicides against the musty-odor cyanobacterium OscillatoriaperornataApplEnviron Microbiol2003. 

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