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• 117-10-2 1,8-dihydroxy-9,10-anthracenedione 

Relevant academic research and scientific papers

Anthraquinones as Photoredox Catalysts for the Reductive Activation of Aryl Halides

Quinones are ubiquitous in nature as structural motifs in natural products and redox mediators in biological electron-transfer processes. Although their oxidation properties have already been used widely in chemical and photochemical reactions, the applications of quinones in reductive photoredox catalysis are less explored. We report the visible-light photoreduction of aryl halides (Ar–X; X = Cl, Br, I) by 1,8-dihydroxyanthraquinone. The resulting aryl radical anions fragment into halide anions and aryl radicals, which react through hydrogen abstraction or C–C bond-forming reactions. The active photocatalyst is generated from 1,8-dihydroxyanthraquinone by photoinduced single-electron reduction to the radical anion or subsequent protonation and further reduction (or vice versa) to the semiquinone anion. Subsequent visible-light excitation of the anthraquinone radical anion or semiquinone anion converts them into very potent single-electron donors. A plausible mechanism for the reaction is proposed on the basis of control experiments and spectroscopic investigations.

Electron Paramagnetic Resonance, ENDOR and TRIPLE Resonance of some 9,10-Anthraquinone Radicals in Solution. Part 3. - Hydroxyanthraquinones

EPR, ENDOR and TRIPLE resonance spectra have been recorded for 1,4-dihydroxy-9,10-anthraquinone, 1,5-dihydroxy-9,10-anthraquinone, 1,8-dihydroxy-9,10-anthraquinone, 2,6-dihydroxy-9,10-anthraquinone, 1,2-dihydroxy-9,10-anthraquinone, 1,2-dihydroxy-9,10-anthraquinone-3-sodium sulphonate and 1,2,5,8-tetrahydroxy-9,10-anthraquinone anion radicals.The hyperfine coupling constants and g factors ar given.Use of a modified additivity relationship allowed assignment of the constants.The spectra of deuterated radicals are discussed.

Substituent Effects in Anthrasemiquinones

Electron spin resonance spectra have been obtained from series of 2-substituted anthrasemiquinones and of 3-substituted 1,8-dihydroxyanthrasemiquinones.The proton splittings are consistently assigned by means of linear correlation plots between splitting constants and a substituent-dependent paramater.All lines in the plots of he two series of compounds obey the following linear equation aRi = AixR + aHi where aHi and aRi are the splitting constants at position i before and after the substituent has been added.Ai is the slope of the line for the splittings from position i and xR is a constant characteristic of the substituent R. xR is comparable to the Hammett ? parameter.Electron-donating substituents at C-2 are shown to increase the spin densities at the positions 1 > 6 > 8, and to decrease them at the positions 4 > 3 > 7 > 5, with the strength of the effect indicated.Electron-withdrawing substituents have the opposite effect.Preliminary Hueckel molecular-orbital calculations qualitatively predict the observed correlations, solely by changing the parameter for the resonance integral.