Anthraquinone, hydroxy derivatives

Anthraquinone is of great technical importance, as many of its derivatives form valuable dyes notable among these are the hydroxy-derivatives (alizarin, etc.)y the amino-derivatives (indanthrene, etc.) and the sulphonic acids. 

Pournaghi-Aznar MH, Shemirani F, Pourtork S (1995) Electrochemical behavior of some naturally occurring hydroxy derivatives of 9,10-anthraquinone in chloroform at mercury and glassy carbon electrodes application of AC polarography to the analysis of Rhubarb roots. Talanta 42 677-684. 

Reaction LVIIL (a) Reduction of Phenols and Quinones by Distillation with Zinc Dust. (A., 140, 205.)—When certain aromatic oxygen compounds (phenols, naphthols, quinones, etc.), are heated with zinc dust, they are reduced to the corresponding hydrocarbons. Thus, phenol yields benzene, the naphthols naphthalene while anthracene can be obtained from anthraquinone or its hydroxy derivatives, alizarin, or quinizarin. In this way alizarin was first proved to be an anthracene derivative. (B., 1, 43.) For catalytic reduction of phenols, see C. r. 193, 1023. 

Fuming sulfuric acid attained importance as an oxidizing agent for the introduction of hydroxyl groups in anthraquinone derivatives in the production of a variety of alizarin dyes. Thus, fuming sulfuric acid at low temperatures may be used to convert alizarin and other hydroxy derivatives of anthraquinone to trihydroxy or up to hexahydroxy derivatives. 

Anthrone or its tautomer anthrol or its hydroxy derivatives (i.e., the aglycones) are found to exert purgative effects. However, the anthraquinone glycosides are usually present in several herbal drugs, such as senna, cascara, rhubarb and aloes. 

In recent years atrochrysone (4) and several other pre-anthraquinones have been isolated from fungi and higher plants (Scheme 2). The parent compound 4 occurs in the toadstools Cortinarius atrovirens and . odoratus (ref. 3). The monomethyl ethers torosachrysone (7) (ref. 4) and asperflavin (8) (ref. 5) are produced by Cassia torosa and Aspergillus flavus, respectively. Torosa-chrysone-8-O-methyl ether (9) has been found in fruitbodies of several toadstools along with its trans-4-hydroxy derivative 10 (ref. 3). Further compounds of this type, e.g. vismione A (11) and B (12), have been isolated from Vismia species (ref. 6). With the only exception of 7, the absolute configuration of these pre-anthraquinones remains unknown. 

Among toadstools belonging to Cortinarius subgenus Phlegmacium the principal pigments are derivatives of 3,4-dihydroanthracen-l (2//)-one and, in contrast to the situation in Dermocybe, anthraquinones themselves play only a subordinate role (617). The pivotal biosynthetic intermediate atrochrysone (321) is present in Cortinarius atrovirens and C. odoratus (Table 28) where it is accompanied by the 4-hydroxy derivatives (322) and (323) of varying stereochemistry. The dimethyl ether... 

Anthraquinone gives predominantly the 2-hydroxy derivatives on photolysis in aqueous propane-2-ol. The nitro group can be replaced by hydroxyl ion. 

In 1901, mercury cataly2ed a-sulfonation of anthraquinone was discovered, and this led to the development of the chemistry of a-substituted anthraquinone derivatives (a-amino, a-chloro, a-hydroxy, and a,a -dihydroxyanthraquinones). In the same year R. Bohn discovered indanthrone. Afterward flavanthrone, pyranthrone, and ben2anthrone, etc, were synthesi2ed, and anthraquinone vat dyes such as ben2oylaniinoanthraquinone, anthrimides, and anthrimidocarba2oles were also invented. These anthraquinone derivatives were widely used to dye cotton with excellent fastness, and formed the basis of the anthraquinone vat dye industry. 

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). 

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. 

Of the various anthracenedione isomers, only the 9,10-compound is used for the synthesis of dyes it is usually referred to simply as anthraquinone (6.1). The parent compound is pale yellow in colour, having a weak absorption band in the visible region (n—>tt transition). The presence of one or more electron-donating substituents leads to significant bathochromic effects so that relatively simple derivatives are of commercial importance as dyes. The colour of such compounds, which usually contain amino or hydroxy groups, can be attributed to the existence of a charge-transfer absorption band [1]. 

Red Anthraquinone Dyes. All the most important red disperse dyes are based upon a l-amino-4-hydroxy substitution pattern. The bluish red shade of the parent dye. Cl Disperse Red 15, can be shifted hypsochromically by putting an elecuon-donating group in position 2, e.g. the 2-OCH3 (Cl Disperse Red 4), the important 2-OPh derivative. Cl Disperse Red 60 and Cl Disperse Red 91 and Red 92. The synthetic pathway to these red anthraquinone disperse dyes is shown in Figure 2.11. 

Amlnochrysammlc or Amlnochrysammlnlc Acid. See 2,4,5,7-Tetranitro-8-amino-1-hydroxy-anthraquinone, described under Aminohydtoxyanthraquinone and Derivatives Aminocompounds are described individually, such as amino acetic acid, aminobenzoic acid, aminocarbazole, aminotetrazole, aniline, etc... 

Note No higher nitrated derivs of amino-hydroxy anthraquinones were found in Beil of CA through 1956... 

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

This reaction is specially interesting since many of the above compounds readily yield the corresponding anthraquinone derivatives (see p. 82), e.g., 4-chloro-l-hydroxy-anthraquinone has been obtained from p-chloro-phenol substituted anthraquinones of this type are becoming increasingly important. 

The Me3Si group in ( )-l,3-bis(trimethylsilyloxy)buta-l,3-diene (177) provides the necessary steric requirement to react with 10-amino-9-hydroxy-l,4-anthraquinone derivatives 176 in a regio- and stereospecific manner (equation 74)230. Thus a single anthracyclinone derivative (178) is obtained in an excellent yield through the Diels-Alder process. 

Blue and turquoise dyes also play an important role. The most important blue dyes come from ring- or V-substituted derivatives of the two isomers of aminodi-hydroxy-anthraquinone 8 and 9. 

The X-ray structures of two anthraquinone derivates of 1,3-dioxane were published. In both 1 -methoxy-4-(2-methylprop-2-enyloxy)-2-[(2i ,6i )-4,4,6-trimethyl-1,3-dioxan-2-yl]-anthraquinone and 4-hydroxy-3-(2-methyl prop-2-enyloxy)-2-[(27 ,67 )-4,4,6-trimethyl-l,3-dioxan-2-yl]anthraquinone the 1,3-dioxane ring adopts the chair conformation and the substituents in positions 2 and 6 are in equatorial conformations (99AX(C)436). Finally, Freeman et al. (02JMS(T)43), employing both ab initio theory and density function theory, calculated the energies of chair, half-chair, sofa, twist, and boat conformers of 1,3-dioxane. 

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). 

The raw materials used to synthesize organic dyes are commonly referred to as dye intermediates. Largely, they are derivatives of aromatic compounds obtained from coal tar mixtures. The majority of these derivatives are benzene, naphthalene, and anthracene based compounds. This section provides an overview of the chemical reactions used to prepare the key intermediates employed in dye synthesis. In this regard, emphasis is placed on halogenated, aminated, hydroxy-lated, sulfonated, and alkylated derivatives of benzene, naphthalene, and anthraquinone. 

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