- 9-Anthracenyl-substitued pyridyl enones revisited: Photoisomerism in ligands and silver(i) complexes
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In solution, (E) to (Z)-isomerism is facile both in 3-(9-anthracenyl)-1- (pyridin-4-yl)propenone, 2, and in its silver(i) complex [Ag(2) 2]+. The crystal structures of (E)-2, (Z)-2 and [Ag{(E)-2}2][SbF6] are presented, and the roles of edge-to-face and face-to-face π-interactions in the lattice are discussed. Solution NMR spectroscopic data suggest that the driving force for (E) to (Z) isomerization is intramolecular π-stacking of the pyridine and anthracene domains. The reversed enone 3-(9-anthracenyl)-1-(pyridin-4-yl)propen-3-one, (E)-3, and the silver(i) complex [Ag{(E)-3}2][SbF6] have been prepared and characterized, including a single crystal X-ray determination of the latter. Surprisingly, no π-stacking between anthracene or pyridine domains is observed in the solid state, and the crystal packing is dominated by Ag...F, CHanthracene...π-pyridine and CH...F interactions. In contrast to (E)-2 and [Ag{(E)-2}2]+, neither (E)-3 nor [Ag{(E)-3}2]+ undergoes photoisomerization in solution.
- Constable, Edwin C.,Zhang, Guoqi,Housecroft, Catherine E.,Zampese, Jennifer A.
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- Nature of the Low-Temperature Emission from 9-Nitroanthracene
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A luminescence study of 9-nitroanthracene indicates that its emission from EPA glasses at 77 K is not molecular phosphorescence but anthraquinon phosphorescence formed via an efficient photochemical reaction.The quantum yield for the reaction at 77 K in ethyl alcohol is estimated to be 0.7.Evidence that 9-nitroanthracene does not phosphoresce was corroborated by forming 1:1 EDA complex with boron trichloride, which results in a stable complex that inhibits its molecular photodecomposition.
- Snyder, R.,Testa, A. C.
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- ELECTRON-TRANSFER REACTIONS AND ASSOCIATED CONFORMATIONAL CHANGES. STUDIES OF BIANTHRONE REDUCTION VIA HOMOGENEOUS REDOX CATALYSIS.
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The catalyzed reductions of bianthrone (1) and 1,1 prime -dimethylbianthrone have been quantitatively characterized in dimethylformamide solvent. The technique that was employed involves the generation of anion radicals of various quinones at a mercury electrode. As they diffuse near the electrode, these anion radicals can transfer an electron to A form of the bianthrone. At low catalyst concentrations, the rate of reduction of 1 is governed by the forward electron-transfer reaction for each of five quinones. the back reaction was shown to be diffusion controlled. The results were compared with radiolysis studies in a different medium. The present work was the result of interest in the significant role of molecular conformation in the thermodynamics and kinetics of electron-transfer reactions. Refs.
- Evans,Xie
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- Excited-State Behavior of Thermally Stable Radical Ions
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The excited states of several families of thermally stable radical ions in solution are surveyed by transient absorption and steady-state fluorescence spectroscopy to determine prevalent deactivation mode(s).Of the species investigated, weak fluorescence can be observed only for substituted triarylamine radical cations, presumably from their lowest excited doublet states.The primary excited-state deactivation pathway for radical anions of the quinones, aryl ketones, and cyanoarene hydrocarbons examined here is internal conversion from the lowest excited doublet state to the ground-state doublet.The efficiency of this deactivation mode arises typically from a low D0-D1 energy gap, as demonstrated by near-infrared absorbance in each species.Contrary to a prior literature report, the 9,10-anthraquinone radical anion and the 9,10-dicyanoanthracene radical anion are nonluminescent in solution.Luminescent side products generated in ground-state reactions of these radical anions are identified as 9,9-bianthrone dianion (from the dimerization and deoxygenation of the anthraquinone radical anion) and 10-cyanoanthrolate (from the reaction of dicyanoanthracene radical anion with molecular oxygen).
- Breslin, David T.,Fox, Marye Anne
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- Electron-Transfer Reactions and Conformational Changes Associated with the Reduction of Bianthrone
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The electrochemical reduction of the low-temperature A form of bianthrone (1A) at a platinum cathod in DMF proceeds in a two-electron, irreversible reaction, giving the dianion 3B which is structurally similar to the high-temperature B form of bianthrone (1B), having two planar ring system twisted about the central connecting bond.The overall reduction involves a large structural change.By contrast, 3B is rapidly and reversibly oxidized to a structurally similar anion radical, 2B, and then to 1B which is not stable at room temperature and converts to 1A as it diffuses away from the electrode.This scheme was confirmed by cyclic voltammetry and transmission-mode spectroelectrochemistry.Rate constants for both the 1A->1B and 1B->1A reactions were determined, and upper limits were put on the rate constants for the direct electrochemical reduction of 1A to 2B or 3B.
- Olsen, Bernard A.,Evans, Dennis H.
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- Synthesis and electro-optical evaluation of 2,6-bis(arylethynyl)anthraxquinones
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A series of 2,6-bis(arylethynyl)anthraquinones was prepared via double Sonogashira coupling to 2,6-diiodoanthraquinone, and characterized with regard to their optical and electronic properties. Substitution with a derivatized phenylethynyl group produced a λonset of 366 nm (Eg = 3.4 eV), but the more highly conjugated 2,6-bis(9'-anthracylethynyl)anthraquinones exhibited a λonset of approximately 540 nm (Eg = 2.3 eV). Poor solubility in the unsubstituted 9'-anthracylethynyl system hampered complete characterization or purification, but the 10'-hexanoylanthrac-9'-ylethynyl analog exhibited significantly better solubility. The preparation of several other functionalized derivatives was also explored, and key synthetic findings are reported.
- Tumuluri, Anusha,Khanna, Bhanupriya,Altalib, Ammar,Revell, Kevin D.
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p. 337 - 343
(2015/06/22)
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- Facile synthesis and lateral πnsion of bisanthenes
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The improved Scholl reaction allows for the direct cyclization of anthracene oligomers to give bisanthene, teranthene, and quateranthene. Furthermore, a variety of πnded bisanthenes are obtained by the Diels-Alder cyclo-addition of bisanthene with several arynes. These reactions would allow us to synthesize various size- and shape-controlled polyperiacenes.
- Konishi, Akihito,Hirao, Yasukazu,Matsumoto, Kouzou,Kurata, Hiroyuki,Kubo, Takashi
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p. 592 - 594
(2013/07/25)
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- METHOD OF PRODUCING DIOL, POLYDIOL, SECONDARY ALCOHOL OR DIKETONE COMPOUND
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The invention is a process of using, as a reducing agent, a 12CaO·7Al2O3 electride containing electrons in a number of 1019 cm-3 or more and 2.3 × 1021 cm-3 or less in its cages to subject a carbonyl compound to reductive coupling in a solvent, thereby synthesizing a diol or polydiol. The invention is also a process of reducing a ketone compound in a solvent, thereby synthesizing a secondary alcohol or diketone compound. According to the process of the invention, it is possible to synthesize a diol or polydiol, or a secondary alcohol or diketone compound through simple operations in a short period without using an expensive and harmful metal hydride or metal salt nor limiting the atmosphere for the synthesis to an inert gas atmosphere as in conventional processes.
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Page/Page column 4-5; 13; 15-16
(2009/06/27)
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- An easy synthesis of thermochromic ethylenes under microwave irradiation
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Thermochromic ethylenes were obtained by the reaction of anthrone with tricyclic ketones or terephthaldehyde in DMF in the presence of potassium ter-butoxide under reflux (8h) or under microwave irradiation (10 min.).
- Villemin, Didier,Hachemi, Messaoud,Hammadi, Mohamed
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p. 260 - 261
(2007/10/03)
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- Spectral-luminescent properties and photoinduced transformations of bisanthene and bisanthenequinone
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Based on the study of photochemical transformations of bisanthene in oxygen-containing solutions, it was established that the final product of this reaction is bisanthenequnone. It is shown that in the course of this oxidation reaction the intermediate compounds endomonoperoxide and bisanthene endobiperoxide are formed. Quantum-chemical calculation of the geometrical structure and electronic spectra of the endoperoxides has shown that they have a nonplanar structure, and their absorption spectra experience a large hypsochromic shift. The absorption and fluorescence spectra of solutions of bisanthene in different solvents at 300 and 77 K were investigated. The large Stokes shift of the fluorescence spectra of the solutions of bisanthene in benzene and in its methyl derivatives is explained by the action of intermolecular interactions. The quasi-line fluorescence spectra of solutions of bisanthene in the matrices of saturated hydrocarbons were recorded.
- Arabei, S. M.,Pavich, T. A.
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p. 236 - 244
(2007/10/03)
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- Thionation of anthrone with sulfur
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The reaction of anthrone with sulfur at room temperature in DMF in the presence of catalytic amounts of pyridine afforded alongside oxidation and dimerization products also thionated compound, monothioanthraquinone.
- Loskutov
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p. 528 - 530
(2007/10/03)
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- Competition between nucleophilic addition and electron-transfer process in the reaction of 9-diazo-10-anthrone with Grignard reagents
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9-diazo-10-anthrone reacts with RMgX (R = Me, Et, Bu(n), 5-hexenyl, Pr(i), benzyl, Bu(t)) essentially yielding 9-alkylazo-10-hydroxy derivatives, which are isolated in their tautomeric quinoid structure as alkylhydrazones of 9,10-anthraquinone. The yields of these compounds decrease as the oxidation potentials (E(OX) of the Grignards decrease: at the same time additional compounds, formed through a radical mechanism, are obtained in higher yields. The reaction has been interpreted as a competition between single electron transfer (SET) and nucleophilic attack, which occur with ratios varying with the oxidation potentials of the Grignard reagents. Evidences for the SET pathway have been found performing an experiment in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as a scavenger of C-centered radicals.
- Bruni, Paolo,Carloni, Patricia,Conti, Carla,Giorgini, Elisabetta,Greci, Lucedio,Iacussi, Marco,Stipa, Pierluigi,Tosi, Giorgio
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p. 6795 - 6802
(2007/10/03)
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- HYDRODIMERISATION ELECTROCHIMIQUE DE CETONES AROMATIQUES ENCOMBREES EN MILIEU APROTIQUE ET EN PRESENCE DE CHLORURE DE CHROME
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The electrochemical reduction of hindered aromatic ketones which are difficult to reduce alone, can be achieved in an aprotic medium (DMF) on a mercury pool cathode, in presence of Cr(III) chloride, at the reduction potential of the Cr(II)/Cr(0) system, but at a less negative potential than that of the ketone itself.There is a selective hydrodimerisation into an α-glycol, with total lack of polimerisation.With disymmetric ketones, the dl-diastereoisomers of the diols are produced.The effect of chromium is due either to the reduction of a Cr-ketone complex or to thereduction of the ketone by a film of colloidal chromium on the electrode surface.
- Fournier, F.,Berthelot, J.,Pascal, Y. L.
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p. 339 - 347
(2007/10/02)
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- Vinylic Cations from Solvolysis. 29. Solvolysis of 9-(α-Bromoarylidene)anthrones as a Probe to the Reactivity - Selectivity Relationship in Solvolysis Reactions
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The solvolyses of 9-(α-bromoarylidene)anthrones 5a (Ar=An), 5b (Ar=Tol), 5c (Ar=Ph), and 5d (Ar=o-An) in 1:1 AcOH-Ac2O/NaOAc and in TFE/2,6-lutidine and of 5a in buffered AcOH and 80percent EtOH were investigated.An extensive common ion rate depression by the formed or added Br- ion was observed.Selectivity constants α=kBr-/kAcO- and α'=kBr-/kTFE or kBr-/K80percentEtOH for competitive capture of the derived cations 14 by Br- vs.AcO- or the solvent were calculated.The α values in 1:1 AcOH-Ac2O, the α' values in TFE, and the reactivities (kt0 values) are structure dependent and follow the order 5a > 5d > 5b.The results for 5c are not sufficiently accurate for reliable selectivity determination.The nature of the capturing nucleophile in AcOH-containing media is discussed and evidence for product formation nearly exclusively from a solvolytically generated free vinyl cation in AcOH, AcOH-Ac2O, and TFE is given.Linear or nearly linear reactivity-selectivity relationships of log kt0 vs. log α or log α' for 5a, 5b, and 5d were obtained, but the selectivity differences are moderate in 1:1 AcOH-Ac2O and small in TFE.This behavior is discussed in relation to Ritchie's constant selectivity rule for stable cations and the linear reactivity-selectivity observed for less selective ions.It is suggested that the different selectivity relationships represent different regions of an overall nonlinear reactivity-selectivity plots for carbonium ion reactions.The merits and disadvantages of measuring selectivities by common ion rate depression are discussed.
- Rappoport, Zvi,Apeloig, Yitzhak,Greenblatt, Jeremy
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p. 3837 - 3848
(2007/10/02)
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- Syntheses and reactions of spirocyclopropaneanthrones. Part 2. Rearrangements and cyclopropyl ring-opening reactions of phenyl-substituted spirocyclopropaneanthrones and related compounds
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Diphenylspirocyclopropaneanthrones [(1c) and (1d)] thermally rearranged with ring expansion to 1,10b-dihydro-2H-aceanthrones (2), whereas the phenyl analogue (1b) did not rearrange under comparable conditions. Phenylspirocyclopropeneanthrone (3a), prepared by the carbenic reaction of 10-diazoanthrone (6) with phenylacetylene, thermally rearranged to 10bH-aceanthrone (11). By contrast, the diphenyl analogue (3b), from the reaction with diphenylacetylene, was thermally stable. The diazoketone (6) reacted with 9-methylenefluorene to give directly the rearrangement product (2g), instead of the dispirocyclopropaneanthrone (1g). Spirocyclopropane-and spirocyclopropene-anthrones [(1) and (3)] reacted under acidic conditions to yield cyclopropyl or cyclopropenyl ring-opened products. In these reactions, the ring was shown to open from the more substituted side. These reactions are discussed in mechanistic terms.
- Hirakawa, Kiyoichi,Nosaka, Toshikazu
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p. 2835 - 2841
(2007/10/02)
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