Hydroxy quinones

Hydroxy- 1,4-quinones.4 Silver oxide oxidizes derivatives of methyl sesamol 1 to quinoncs of this type (equation I). 

Oxy-aldehyd, n, hydroxy aldehyde, -ammo-niak, n, oxyammonia (hydroxylamine), -azoverbindung, /. hydroxyazo compound, -benzol, n, hydroxybenzene (phenol), -bem-steinsaure. /, hydroxysuccinic acid (malic acid). -biazol, n. oxadiazole, oxdiazole. -bitumen, n, oxidized bitumen, -carbon-s ure, /, hydroxycarboxylic acid, -chlnoltn, n. hydroxyquinoline, -clunon, n. hydroxy-quinone. -chlorid, n. oxychloride, -chlor-kupfer, n. copper oxychloride, -cyan, n. oxycyanogen. 

Although treated as separate classes in the Colour Index, these structural types are closely related and the few diphenylmethane dyes such as auramine (1.28 Cl Basic Yellow 2) are now of little practical interest. Commercial usage of the triarylmethane dyes and pigments has also declined considerably in favour of the major chemical classes. They were formerly noteworthy contributors to the acid, basic, mordant and solvent ranges, primarily in the violet, blue and green sectors. Numerous structural examples are recorded in the Colour Index. The terminal groupings can be amine/quinonimine, as in auramine and crystal violet (1.29 Cl Basic Violet 3), hydroxy/quinone, or both. The aryl nuclei are not always benzenoid (section 6.5). 

Quinones, typical of unsaturated ketones, undergo base-catalysed epoxidation The epoxy ketone may then rearrange with the formation of a hydroxy quinone. Quinones may also act as dienophiles in the Diels-AIder reaction. This can be a useful way of constructing polycyclic ring systems (Scheme 3.54). 

Corbett JF (1966) The chemistry of hydroxyquinones. Part I. The reaction of 2-hydroxybenzoquinones with alkaline hydrogen peroxide. J Chem Soc (C) 2308-2311 Corbett JF, Fooks AG (1967) The chemistry of hydroxy-quinones. Part III. The reactions of 2,5-dihydroxy-benzoquinones with alkali. J Chem Soc (C) 1909-1913 Dence CW (1971) Halogenation and nitration. In Sarkanen KV, Ludwig CH (eds) Lignins. 

Chloranilic Acid.—Hydroxyl substitution products of quino e are important as they yield salts with bases which are intensely colored and therefore valuable as dyes. The most important one of these compounds is a di-hydroxyl product of a quinone related to anthracene and known as alizarin. A mixed chlorine and hydroxyl substitution product is the di-chlor di-hydroxy quinone. It is chloranil in which two of the chlorine atoms have been replaced by hydroxyl groups, and is known as chloranilic acid. 

Quinone Cleavage and Resistance to Peroxide Treatment Hydrogen peroxide readily oxidizes o- and p-quinones via ring cleavage, forming colorless, open-chain carboxylic acids [21]. This is the predominant reaction, however, colored products may also be formed, particularly at high alkali concentrations. There is firm evidence for the formation of hydroxy-substituted quinones. In addition, the formation of quinone polymers has also been proposed. The hydroxy-quinones are probably formed... 

In a separate study, Pero and Deuce [52] also found methoxy-l,4-benzoquinone difficult to bleach with peroxide. They postulated that both hydroxy-quinone and quinone condensation products were formed. 

As expected, the ease of fission of aryl ethers parallels their ease of formation ethers of nitrophenols, for example, can be hydrolysed by even gentle warming with alcoholic potassium hydroxide. Polynitrophenyl ethers are often cleaved even by water, ammonia, or primary or secondary amines.33 Ethers of hydroxy quinones are also decomposed by cold dilute sodium hydroxide solution.34... 

Watanabe, K., N. Usami, I. Yamamoto, and H. Yoshimura (1991). Inhibitory effect of cannabidiol hydroxy-quinone, an oxidative product of cannabidiol, on the hepatic microsomal drug-metabolizing enzymes of mice. J. Pharmaco-biodyn. 14, 421 27. 

This reaction is useful for the structural determination of hydroxy quinone, and in the preparation of some quinone derivatives that might be difficult to make. 

Bomheim LM, Grille MP (1998) Characterization of cytochrome P450 3A inactivation by cannabi-diol possible involvement of cannabidiol-hydroxy-quinone as a P450 inactivator. Chem Res Toxicol 11 1209-1216... 

Studies of the metabolism of vitamin E were triggered by the observations of Alaupovic and coworkers [126, 127]. When " [Cj-D-a-tocopherol-5-methyl was administered to rats or pigs and attempts were made to detect metabolic derivatives, two compounds were separated by chromatography. One of the compounds is " [C]-D-a-tocopherol quinone the other is either a dimer or a trimer of a-tocopherol. The dimer and trimer are terminal oxidation products of a-tocopherol and are excreted in the bile. a-Tocopherol quinone can be converted to a-hydroquinone. a-Tocopherol hydroquinone may be esterified in liver and eliminated in the feces after concentration in the bile and excretion in the intestine, or it may be oxidized in the kidney to a-tocopheronic acid, which may be converted into an a-tocopheronolactone conjugate, which is excreted in the urine. In conclusion, vitamin E is excreted as such in the urine or the bile after conversion to a dimer or a trimer, in the form of a conjugated hydroxy-quinone or tocopheronic acid (see Fig. 4-43). 

Quinones Barrier [6] has separated some benzoquinones on silica-starch layers, using hexane-ethyl acetate (85 + 15). Pettersson [169] later made a detailed comparison of the chromatographic behaviour of benzoquinones, of which 31 contained hydroxyl group(s) and 21 were without. Neutral solvents, especially mixtures of benzene-chloroform and xylene, were suitable for the last named. The basic solvent VIII (Table 166) was better for the more polar hydroxy-quinones they migrate as enolates in this system. The hi /-values on silica gel layers of some recently discovered [170] fungus colouring materials are given below they were obtained with solvent VIII (values without brackets) and chloroform (values in brackets) ... 

One further way in which this phenomenon can arise, is when the carbonyl group is part of a ring system but maintains the a 3-unsaturation and the OH substitution on the 3 carbon atom. Such cases are 1-hydroxyanthraquinones, anthrones and oxanthrones, which have been extensively studied by Flett [32] and Hada and Sheppard [134], and the hydroxy quinones studied by Josien et al. [73]. 

Fig. 62. Use of hydroxy quinones in the formation metal-chelate polymers...

Naphthalene hydrocarbons halogen compounds, nitrogen compounds. (1949.) hydroxy compounds. (l950.) oxo-compounds except quinones. (1950.) quinones. (1962.)... 

Thallium trinitrate oxidi2es naphthols and hydroquinone monoethers, respectively, to quinones and 4,4-diaIkoxycyclohexa-2,5-dienones, eg, 4,4-dimethoxy-2-methyl-2,5-cyclohexadienone [57197-11 -2] (108) (111,112). The yield of (108) is 89%. Because the monoacetal is easily converted to the quinone, the yield of 5-hydroxy-l,4-naphthoquinone [481-39-0] is 64%. 

Some other inhibitors from the patent literature include hydroquinone [129], ionoP [130], and quinone [131]. Other inhibitors used to stabilize MMA include butylated hydroxy toluene (BHT), phenothiazine, methylene blue, hydroxy-diphenylamine and di-/jc/<3-napthol [132]. Several good reviews of inhibition and inhibitors have been written [133-136]. The mechanisms of inhibition are subtle and complicated. For example, it has been reported that highly purified benzo-quinone acts as a retarder rather than an inhibitor [137]. It has been proposed... 

Mercaptoquinolines of this type exist in the zwitterion or the zwitterion-extended quinone form to a greater extent than do the analogous hydroxy compounds ° (see Table V and Section II,R), and the color of 8-mercaptoquinoline has been attributed to the zwitterion structure.The concentration of the zwitterion decreases as the dielectric constant of the solvent decreases in the order H2O > MeOH > EtOH > Bu OH as indicated by the change in the molecular extinction coefficient. ... 

Ethoxy-3//-azepin-3-ones, e.g. 2, are produced rapidly (2-20 min), as yellow gums, by the oxidation of 7-ethoxy-6-hydroxy-4/T-azepines,e.g. 1, with2,3-dichloro-5,6-dicyano-l,4-benzo-quinone (DDQ) in benzene.48,51... 

The vast majority of azo dyes are azo compounds containing hydroxy or amino groups in the 2- or 4-position with respect to the azo group (e.g., 1.8). They are in equilibrium with their tautomers, the quinone hydrazones (quinone monoimine hydrazones). In spite of the fact that in most hydroxyazo dyes the equilibrium is shifted in favor of the quinone hydrazone, they are still called azo compounds. 

Anion-catalyzed phase transfer catalysis in a dichloromethane-aqueous sulfuric acid two-phase system was successfully applied to the diazotization of pen-tafluoroaniline by Iwamoto et al. (1983 a, 1984). If this compound is diazotized in dilute aqueous acid, tetrafluoro-l,4-quinone diazide is obtained, indicating that the diazotization proper is followed by a hydroxy-de-fluorination (Brooke et al., 1965). 

On the other hand, there is at least one case of an aromatic amine without a hydroxy group in the 2-position, namely 1-aminophenazine (2.29) which, after the initial diazotization, is oxidized within minutes by air or additional nitrous acid to the quinone diazide 2.31 (Olson, 1977). 

The general applicability of this type of synthesis of quinone diazides is nevertheless limited since, depending on the type and number of substituents in the 2-, 4-, and 6-positions of benzenediazonium ions, either hydroxy-de-diazoniation (reaction A in Scheme 2-20) or nucleophilic substitution of one of the groups in the 2-, 4-, or 6-position (reaction B) will predominate. It is difficult to predict the ratio of the two reactions in a specific case. This is exemplified by two investigations carried... 

Compounds which correspond to 1,2-quinone diazides can also be obtained by diazotization of aromatic and nonaromatic heterocyclic amines with a hydroxy group in the ortho position. Examples include 3,4-quinolinequinone-3-diazide (2.35, Sus et al., 1953 Sus and Moller, 1955) and 3-diazochromane-2,4-dione (2.36, Arndt et al., 1951). Syntheses of more complex heterocyclic quinone diazides have been tabulated by Ershov et al. (1981, p. 105). More recent publications are cited in a paper by Tisler s group (Klotzer et al., 1984). 

Quinoline-5-sulfonic acid, 8-hydroxy-7-iodo-metal complexes absorptiometry, 1,549 Quinolinium salts in gravimetry, 1, 535 Quinolinol metal complexes color photography, 6,107 8-Quinolinol biological activity, 6, 771 gallium and indium complexes radiopharmacology, 6, 971 radionuclide complexes radiopharmacology, 6,994 8-Quinolyl sulfate hydrolysis metal catalysis, 6,465 Quinones... 

The ortho-quinone methides are difficult to isolate due to their high reactivity, which leads to rapid Diels-Alder dimerization or trimerization (Fig. 7.26). At 150°C, a partial retro-Diels-Alder reaction of the trimer can occur to form ortho-quinone methide and bis(2-hydroxy-3,5-dimethylphenyl) ethane (dimer).51... 

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