Anthraquinone 1-hydroxyanthraquinone

It was also observed that if the NO pressure was raised above 15-40 torr the quenching efficiency diminished with anthraquinone, / -hydroxyanthraquinone, and jS-aminoanthraquinone in both the vapor and adsorbate with /3-methylanthraquinone quenching diminished in the adsorbate but not in the vapor. To explain these observations, Karyakin et al. introduced the following quenching mechanism for the first three molecules and the adsorbate of / -methylanthraquinone (all called A for simplicity)... 

Prepared by condensing p-chlorophenol with phlhalic anhydride in sulphuric acid solution in the presence of boric acid. The chlorine atom is replaced by hydroxyl during the condensation. It can also be prepared by oxidation of anthraquinone or 1-hydroxyanthraquinone by means of sulphuric acid in the presence of mercury(ll) sulphate and boric acid. 

Included in this grouping are D C Green No. 5 (13), a water-soluble sulfonate, D C Green No. 6 (14), an unsulfonated water-insoluble compound, and D C Violet No. 2 (29), a water-insoluble hydroxyanthraquinone. Anthraquinone color additives, in general, are light stable and have good physical and chemical properties for use in cosmetics (see Dyes, ANTHRAQUINONE). 

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. 

Efforts have also been made to overcome compHcated processes. Methods to reduce the number of steps or to use new starting materials have been studied extensively. l-Amino-2-chloro-4-hydroxyanthraquinone (the intermediate for disperse red dyes) conventionally requires four steps from anthraquinone and four separation (filtration and drying) operations. In recent years an improved process has been proposed that involves three reactions and only two separation operations starting from chloroben2ene (Fig. 2). 

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). 

Upon heating anthraquinone with fuming sulphuric acid at 160° for about 1 hour, the main product Is anthraquinone-p-sulphonic acid, which is isolated as the sparingly soluble sodium salt. The latter when heated imder pressure with sodium hydroxide solution and an oxidising agent (sodium or potassium chlorate) yields first the corresponding hydroxy compound further hydroxy-lation occurs in the a-position through oxidation by the chlorate and 1 2-di-hydroxyanthraquinone (alizarin) is formed. 

C-NMR. The structures of the leuco derivatives of l,4-bis(butylamino)-anthraquinone (14) and l-butylamino-4-hydroxyanthraquinone (15) have been shown to be l,4-bis(butylamino)-2,3-dihydroanthracene-9,10-dione (16a) and l-butylamino-10-hydroxy-2,3-dihydroanthracene-4,9-dione (17a), respectively. On the other hand, leuco-1,4-dimethoxyanthraquinone has been assigned the structure, 1,4-dimethoxy-9,10-dihydroxyanthracene (18). 

It is well known that quinizarin (22) is alkylaminated in air to give a mixture of l-alkylamino-4-hydroxyanthraquinone (23), l,4-bis(alkylamino)-anthraquinone (24), and 2-alkylaminoquinizarin (25) (Scheme 7). The reaction conditions affect the ratio of these products. In a nitrogen atmosphere, or in the presence of sodium dithionite as reducing agent, the main amination product is 24. The solvent effects of the reaction of leuco... 

Heterocyclic ring systems are also used to connect two anthraquinone groups. Typical examples include Cl Vat Red 10 (6.106), which is an oxazole derivative obtained from 2-amino-3-hydroxyanthraquinone and the appropriate acyl chloride, the similar thiazole derivative Cl Vat Blue 31 (6.107) and the oxadiazole derivative Cl Vat Blue 64 (6.108). 

This chapter classifies polycyclic pigments by chemical constitution. The resulting classes include aminoanthraquinones, hydroxyanthraquinones, heterocyclic and polycarbocyclic anthraquinone pigments. 

As described, other nucleophilic reactions in the anthraquinone series also involve the production of anion-radicals. These reactions are as follows Hydroxylation of 9,10-anthraquinone-2-sulfonic acid (Fomin and Gurdzhiyan 1978) hydroxylation, alkoxylation, and cyanation in the homoaromatic ring of 9,10-anthraquinone condensed with 2,1,5-oxadiazole ring at positions 1 and 2 (Gorelik and Puchkova 1969). These studies suggest that one-electron reduction of quinone proceeds in parallel to the main nucleophilic reaction. The concentration of anthraquinone-2-sulfonate anion-radicals, for example, becomes independent of the duration time of the reaction with an alkali hydroxide, and the total yield of the anion-radicals does not exceed 10%. Inhibitors (oxygen, potassium ferricyanide) prevent formation of anion-radicals, and the yield of 2-hydroxyanthraquinone even increases somewhat. In this case, the anion-radical pathway is not the main one. The same conclusion is made in the case of oxadiazoloanthraquinone. 

Chrysammidic Acid. See 2,4,5,7 -Tetranitro - 8 -amino 1 - hydroxy-anthraquinone under Amino-hydroxyanthraquinones and Derivatives, Vol 1, pA217-L... 

The ability of the 1-hydroxyanthraquinone system to form chelate complexes is, however, still employed in the synthesis of certain anthraquinone dyestuffs since it permits selective reactions to be carried out. Thus, treatment of the borate ester (215) of 1,2-dihydroxyanthraquinone with acetic anhydride yields l-hydroxy-2-acetoxyanthraquinone, the 1-hydroxy group being protected against electrophilic attack as a result of its being involved in coordination to boron. 

Commercial alizarin may be contaminated with anthraquinone and its derivatives devoid of tintorial value, such as hydroxyanthraquinone and certain dihydroxyanthraqu inones (anthraflavic and isoant hr aflavic... 

In order to strip the dyes of madder dyeings completely from the fiber, they must be extracted in acid solution at temperatures up to roughly 100° C. Comparative solutions produced by extraction from dyer s plants such as madder root must also be prepared in the same manner at acid pH for the TLC. The anthraquinone dyes are present in the dyer s plants partly in the form of glycosides. These glycosides must be split hydrolytically with acids in order to obtain for the TLC a comparative solution that contains only free hydroxyanthraqui-nones and no hydroxyanthraquinone glycosides. 

Although 2-hydroxy-5-tcrt-butylazobenzene (29) exists as a true azo compound, annelation of the benzene ring results in 1,2-naphthoquinone 1-phenylhydrazone (35, R = H) and 1,2-naphthoquinone 2-phenylhydrazone (34, R = H) being in a prevailing tautomeric form in compounds derived from 1-naphthol and 2-naphthol. 4-Hydroxyazobenzene (32) and l-hydroxy-4-phenylazonaphthalene (36, R = H) exist in DMSO as true azo compounds. Next step in annelation of the benzene ring in the passive component led to anthracene derivatives. These compounds exist almost completely in hydrazone tautomeric forms (>95%) irrespective of the fact they were formally derived from 1-hydroxyanthraquinone or 2-hydroxyanthraquinone.50 15N chemical shifts show nicely the dramatic changes for compounds 32, 36, (R = H) and 1,4-anthraquinone phenylhydrazone (44). 

In addition to hydroxyanthraquinones such as alizarin, which is derived from shikimate, glutamate and mevalonate precursors, higher plants produce some polyketide anthraquinones identical to those of microbial origin. Of particular interest is the cooccurrence in root extracts of Aloe species of the 2-methylanthraquinone chiysophanol (63) and the isomeric 1-methylanthraquinone aloesaponarin II (64), since in microorganisms 63 has only been isolated fi om fungal species whereas 64 is the product of a recombinant streptomycete (Figure 7). 

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). 

D-Glucosides of several hydroxyanthraquinones have been reported. For example, Schunk and Marchlewski isolated rubiadin D-glucoside from madder root. This compound was later synthesized by Jones and Robertson and shown to be 3-(/3-D-glucopyranosyloxy)-l-hydroxy-2-methyl-anthraquinone. 

A series of anthraquinones has been chemically synthethized and the influences of structural features, such as the different functionalities in the nucleus have been studied in relation to cytotoxicity toward neoplastic cells. l,3-dihydroxy-9,10-anthraquinone synthetic derivatives were tested in vitro for inhibition against several different human cancer cell lines. Structure-activity analysis indicates that epoxidation of the hydroxyanthraquinone increased cytotoxicity against tumor cells, but ring-opening of the epoxide... 

Rubiaceaous plants are usually rich in anthraquinones. The first four anthraquinones, 2-methyl-3-methoxyanthraquinone (7), 2-methyl-3-hydroxyanthraquinone (8), 2-methyl-3-hydroxy-4-methoxyanthraquinone (9) and 2,3-dimethoxy-6-methylanthra-quinone (10) reported in genus Hedyotis were isolated from H. diffusa [26]. All the compounds except for (10) are substituted only in ring C. The structure of (10) has been later confirmed by synthesis based on Diels-Alder reaction. This anthraquinone has been the only one reported from a natural source until today. Other anthraquinones possessing the same substitution pattern are synthetic products [27]. 

Hydroxyanthraquinone shows more intense M-CO and M-OH peaks than does 1-hydroxy-anthraquinone. Both hydroxyanthraquinone spectra have a peak at m/z 140 corresponding to the loss of three molecules of carbon monoxide, the third arising from the phenolic group. 

The study of the photochromism of a series of anthraquinone derivatives (487) has been reported. The reaction involves the Norrish Type II hydrogen transfer from a neighbouring methyl group to a photoexcited carbonyl group yielding the enol (488). The photohydroxylation of anthraquinone in aqueous organic solvents has shown that both 1- and 2-hydroxyanthraquinone are produced. " A... 

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