Polycyclic quinones

Another important qninone is anthanthrone, especially its dibromo derivative (2.73), Cl Pigment Red 168. This latter pigment is scarlet in colonr and shows excellent resistance to solvents and is one of the most light fast and weather fast pigments known. It is nsed in high-grade paints. 

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While the reduction of polycyclic quinones to phenols, hydroquinones,... 

An alternative route to pyranthrone, involving baking 1,6-dibenzoylpyrene (6.96) with aluminium chloride, was also devised by Scholl (Scheme 6.18). The Scholl reaction is a key step in the synthesis of several polycyclic quinones the cyclisation of 1-benzoylnaphthalene to give benzanthrone (6.73) has already been mentioned. The mechanism of this cyclodehydrogenation reaction may involve an initial protonation step, if traces of water are present, or complexation with aluminium chloride. Electrophilic substitution is thereby... 

Isoviolanthrone (109) is an highly anellated polycyclic quinone system. It is derived from the chemical structure of isodibenzanthrone, which may be visualized as being obtained by unsymmetrical condensation of two benzanthrone molecules. The compound itself affords an intense blue shade. 

Pierce, R., and M. Katz, Chromatographic Isolation and Spectral Analysis of Polycyclic Quinones. Application to Air Pollution Analysis, Environ. Sci. Technol., 10, 45-51 (1976). 

Cyclocondensation of 3-diethylamino-5-phenylethynyl-l,4-naphthoquinone with hydrazine resulting in the closure of a pyridazine ring is reported. This hydrazine condensation was unknown for peri-acetylenic derivatives of polycyclic quinones <2000TL771>. 

The simplest quinones are o- and p-benzoquinone [(3) and (4) respectively]. This quinonoid structural feature is widespread in naturally occurring compounds isolated from moulds, fungi, lichens, plants and insects,52 which include not only substituted benzoquinones but also substituted polycyclic quinones [i.e. the substituted analogues of, for example, 1,2-naphthoquinone (5), 9,10-anthraquinone (6), and 9,10-phenanthraquinone (7)]. 

Vat cotton, rayon, and wool water-insoluble dyes solubilized by reducing with sodium hydrogensulfite, then exhausted on fiber and reoxidized anthraquinone (including polycyclic quinones) and indigoids... 

In chapter 7, special emphasis has been placed on the synthesis of representative polycyclic quinones and their photochromic behavior, including the spectral, kinetic, and fatigue characteristics of such systems. Potential applications are focused on recording and multiplication of images, optical memories, and gradation masking. 

Photochromic compounds functioning by an oxidation-reduction mechanism (electron transfer), especially a photoreduction mechanism, are known in inorganic materials such as silver halides, which are utilized in eyewear lenses. Although the number of organic photochromic compounds operating via electron transfer is fewer than those by isomerization, heterolytic (or homolytic) cleavage, and pericyclic reactions, several classes of compounds have been reported, such as thiazines,1 viologens,2 and polycyclic quinones.3... 

Oxidation of arenes (8, 80-81). This oxidation can be carried out in a two-phase system with sodium dodecyl sulfate as a micellar catalyst. CAS can be used in catalytic amounts if ammonium persulfate is used in excess to convert Ce(lll) as formed to Ce(lV). This oxidation is slow in the absence of a Ag(l) salt. This catalytic two-phase oxidation is very useful for preparation of polycyclic quinones from hydrocarbons, but is ineffective for other substrates. 

Hydriodic acid is recommended for reduction of polycyclic quinones and phenols to polycyclic arenes. ... 

Polycyclic quinones are prepared by careful oxidation of the corresponding hydrocarbons with chromic-sulfuric acid mixture in acetic acid solution or as an agitated aqueous suspension, e.g., 2,3-dimethy 1-1,4-naphthoquinone (80%), 9,10-phenanthroquinone (80%), and acenaphthene-quinone (60%). A laboratory reactor has been described in which an acetic acid solution of chromic acid and another solution of hydrocarbon are mixed as a film at 90°. The reaction mixture is then fed into water to prevent ftirther oxidation. By this procedure, the yield of 2-methyl-1,4-naphthoquinone has been raised from 29% by the usual process to... 

Polymethylquinones and certain polycyclic quinones are prepared by the oxidation of aminophenols and their polycyclic analogs. The latter substances are readily obtained by coupling the corresponding phenolic compound with diazotized sulfanilic acid followed by a reductive cleavage of the azo compound. 

Intermolecular photoelimination of HX has been employed in the syntheses of naphtho[2,l-g]quinoline-7,12-diones, of polycyclic quinones/ and of S-phenylpyridines the reaction has also found use in the trifluoromethyla-tion of imidazoles. ... 

A variation of the ketone to alkene transformation is conversion of quinones into arenes, for which a number of reagent systems have been employed. Over a century ago, the reduction of polycyclic quinones to aromatic systems with phosphorous and hydroiodic acid at elevated temperatures was reported. These conditions, however, resulted in complex reaction mixtures consisting of phenols and polyhydrogenated products. More recently, Konieczny and Harvey have reported the reduction of qui-... 

Other methods to reduce polycyclic quinones to arenes that have met with some success include SnCU/HCl, 58 Zn/NH3, 59Zn/pyridine/MeC02H, NaBH4/BF3-Et20, 6 and NaBH4 in MeOH. All of these methods are compatible with aryl halides and the latter two are also compatible with aryl ethers, anilines and phenols. lO-Arylmethylene-9-anthrones have also been reduced to anthracenes with dibo-rane (Scheme 75). ... 

The photophysics of the polycyclic quinone hypericin and its analogs has been studied quite exhaustively by Petrich and co-workers [57]. The interest in this compound stems from its proven antiviral activity, induced by light. Ultrafast time-resolved transient absorption studies indicate that ESIPT is the primary non-radiative process in hypericin. 

Polycyclic aromatic hydrocarbons Alkylated aromatic hydrocarbons Chlorinated aromatic compounds Chlorobenzenes Polychlorinated biphenyls Polychlorinated dibenzo[l,4]dioxins Chlorinated guaiacols and catechols Nitrogen-containing aromatic compounds Azaarenes and aromatic nitriles Oxygenated aromatic compounds 2,4-Dipentyl phenol Polycyclic quinones and ketones Aliphatic carboxylic acids Cs and C, dicarboxylic acids... 

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