Antraquinones

BALLY - SCHOLL BenzanihreneSynthesis Synthesis of polycondensed aromatics from antraquinone and tnols. 

Treatment of 228 with 2,4-dinitrofluorobenzene (227) provided 230. The assumed intermediate A -benzoyl-A -(2,4-dinitrophenyl)-A -phenylhydrazine (229) underwent the denitrocyclization reaction in its enol form (80JOC3677). Similar reaction is probably involved also in the thermal cyclization of antraquinone 231 leading to 232 (Scheme 35), which took place even during attempts to crystallize the compound (60T107). 

Cochineals contain several compounds with antraquinonic structures the most important is carminic acid. An nncommon chemical featnre of carminic acid and its derivatives is the presence of a C-glncosidic bond (Fignre 5.2.2). 

Males et al. [103] used aqueous mobile phase with formic acid for the separation of flavonoids and phenolic acids in the extract of Sambuci flos. In a cited paper, authors listed ten mobile phases with addition of acids used by other investigators for chromatography of polyphenolic material. For micropreparative separation and isolation of antraquinone derivatives (aloine and aloeemodine) from the hardened sap of aloe (Liliaceae family), Wawrzynowicz et al. used 0.5-mm silica precoated plates and isopropanol-methanol-acetic acid as the mobile phase [104]. The addition of small amounts of acid to the mobile phase suppressed the dissociation of acidic groups (phenolic, carboxylic) and thus prevented band diffusions. 

The EPR spectra of electrolytically produced anion radicals of Q -aminoanthraquin-ones were measured in DME and DMSO. The isotropic hyperfine coupling constants were assigned by comparison with the EPS spectra of dihydroxy-substituted antraquinones and molecular-orbital calculations. Isomerically pure phenylcarbene anion (PhCH ) has been generated in the gas phase by dissociative electron ionization of phenyldiazirine. PhCH has strong base and nucleophilic character. It abstracts an S atom from and OCS, an N atom from N2O, and an H atom from... 

Haider, R. and Lawal, A. (2007). Experimental studies on hydrogenation of antraquinone derivative in a microreactor. Catalysis Today, 125, 48-55. 

The concentration of Cd(II) was determined using a carbon paste electrode modified with organofunctionalized amorphous silica with 2-benzothiazolethiol [402] or diacetyldioxime [403] and differential pulse anodic stripping voltammetry. The same method was used for determination of Cd(II) ion using GC electrode modified by antraquinone improved Na-montmorillonite nanoparticles [404]. 

There are several cases of hydroxylation according to the hidden radical mechanism, within a solvent cage. As assumed (Fomin Skuratova 1978), hydroxylation of the anthraquinone sulfonic acids (AQ-SO3H) proceeds by such a pathway, and OH radicals attack the substrate anion radicals in the solvent cage. Anthraquinone hydroxyl derivatives are the final products of the reaction. In the specific case of dimethylsulfoxide as a solvent, hydroxyl radicals give complexes with the solvent and lose their ability to react with the antraquinone sulfonic acid anion radicals (Bil kis Shein 1975). The reaction is stopped just after anion radical formation, Scheme 1-102 ... 

Figure 11.12 Cyanine dye 1 and antraquinone disulfonate 2 used by McBranch and Whitten.73...

Kirci, H., Bostanci, S., and Yalinkilic, M. K., A new modified pulping process alternative to sulfate method alkali-sulfite-antraquinone-ethanol (Asae). Wood Sci Technol 1994, 28 (2), 89-99. 

In the antraquinone part of the molecule, the only atom without a coupling partner was C2, which revealed the site of decarboxylation. Combined with the fact that the first ("western") ring contained two and not three intact [13C2] units,... 

Retinyl esters Retinyl esters Retinyl esters Carotenoid isomers N-nitrosodiethanolamine in cosmetics Aloins, and related constituents of aloe Food colorants and aromatic glucoronides Azo and antraquinone textile dyes Alkaloids... 

Antraquinone sulphonate absorbs a quantum of light yielding an excited singlet (13a), which is transformed to a triplet by an intersystem crossing (see ref. [73] for explanation of this term) (13b). The latter is reduced by a chloride ion. The generated chlorine atom initiates polymerization (13e). In this process, antraquinone sulphonate is reduced to an anthraquinol derivative. 

Acetogenin consists of fatty acids, fats, waxes, flavonoids, antraquinones, phloroglucinol. 

Rhei rhapontici radix (2) contains anthraquinone aglycones and monoglucosides in low concentration only. In addition tire prominent violet-blue fluorescent stilbene derivatives rhaponticoside/deoxyrhaponticoside (R, 0.45-0.55/T2) are present. They overlap the antraquinone monoglucoside zone. 

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