- Photoinduced electron transfer between 2-methylanthraquinone and triethylamine in an ionic liquid: Time-resolved EPR and transient absorption spectroscopy study
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Photoinduced electron transfer between 2-methylanthraquinone (MeAQ) and triethylamine (TEA) in a room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), was investigated by comparing the time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and the transient absorption spectroscopy. The results of TR-EPR spectroscopy, in which MeAQ was 8 mmol L-1and TEA was 150 mmol L-1, indicated that the transient radical would exist longer time in [bmim][PF6] than in acetonitrile. At the delay time of 8 μs after laser excitation, the TR-EPR signal transformed from an emissive peak into an absorptive peak when the experiment was performed in [bmim][PF6]. The results of the transient absorption spectroscopy, in which MeAQ was 0.1 mmol L-1and TEA was 2.2 mmol L-1, showed that the efficiency and the rate of the photoinduced electron transfer reaction in [bmim][PF6] were obviously lower than that in acetonitrile. It was concluded that various factors, such as concentration, viscosity and local structural transformation of the solution, have an influence on the process of photoinduced electron transfer in [bmim][PF6].
- Zhu, Guanglai,Wang, Yu,Fu, Haiying,Xu, Xinsheng,Cui, Zhifeng,Ji, Xuehan,Wu, Guozhong
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Read Online
- Liquid-phase cascade acylation/dehydration over various zeolite catalysts to synthesize 2-methylanthraquinone through an efficient one-pot strategy
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Liquid-phase cascade acylation/dehydration reactions over various zeolite catalysts were performed to synthesize 2-methylanthraquinone (2-MAQ). Many characterization techniques such as NH3-TPD, pyridine- IR, BET, XRD, SEM, TEM, XRF, and TGA have been employed to study the relationship between the catalytic behavior and the nature of catalysts. The present work provides evidence that the acidity, pore size, particle size, and surface area of zeolites strongly affect both the catalytic properties and the coke formation. Moreover, it is discovered that the reaction activity of phthalic acid (PA) is higher than that of phthalic anhydride, and the yield of 2-MAQ reached 82.2% when PA was used, which opened a new avenue for one-pot synthesizing 2-MAQ by using PA as an acylation reagent. The catalyst can be recycled four times only with a slight decrease in activity. The nano-sized H-beta zeolite could be a promising liquid-phase cascade acylation/dehydration catalyst for clean one-pot synthesis of 2-MAQ.
- Hou, Qijun,Zheng, Bumei,Bi, Chenguang,Luan, Jimei,Zhao, Zhongkui,Guo, Hongchen,Wang, Guiru,Li, Zongshi
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- Electroreductive Cleavage of Substituted 9,10-Anthraquinones in 50percent Aqueous THF Buffers: A pH-Dependent Process
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A variety of substituted 9,10-anthraquinones with acetate leaving groups (4a-7a) were reduced at a glassy carbon electrode in 50percent aqueous THF prepared from aqueous buffers at pH 6, 7, and 8.Cyclic voltammograms of these compounds exhibited a single reduction wave with Ep values of -450 to -530 mV (vs Ag/AgCl/0.10 M Cl-) at pH 7.Ep shifted to more negative values with increasing pH (45-50 mV/pH unit) consistent with a 2e-/2H+ reduction process which converts 4a-7a to their corresponding anthrahydroquinones.Constant potential reduction of acetates 4a-7a at -800 mV at pH 6 or 7 gave n values of 2.2-2.4.Air oxidation of the catholytes, a procedure that converts anthrahydroquinones to anthraquinones, led to a 56-89percent recovery of the acetates and 7-32percent yields of the reductive cleavage products 4b-7b.In contrast, electroreduction of 4a-7a at pH 8 gave much higher yields (50-73percent) of 4b-7b with n values of 3.5-3.8.This pH-dependent process suggests that 4a-7a cleave much slower via their intermediate anthrahydroquinones than the conjugate bases of their anthrahydroquinones, which are present in relatively high concentration at higher pH.NaOH titration curves of the anthrahydroquinones of 5a and 5b support this mechanistic picture.
- Blankespoor, Ronald L.,Hsung, Richard,Schutt, David L.
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Read Online
- Inhibitory activities of anthraquinone and xanthone derivatives against transthyretin amyloidogenesis
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Transthyretin is a tetrameric protein which functions as a transporter of thyroxine and retinol-binding protein. Misfolding and amyloid aggregation of transthyretin are known to cause wild-type and hereditary transthyretin amyloidosis. Stabilization of the transthyretin tetramer by low molecular weight compounds is an efficacious strategy to inhibit the aggregation pathway in the amyloidosis. Here, we investigated the inhibitory activities of anthraquinone and xanthone derivatives against amyloid aggregation, and found that xanthone-2-carboxylic acid with one chlorine or methyl group has strong inhibitory activity comparable with that of diflunisal, which is one of the best known stabilizers of transthyretin. X-ray crystallographic structures of transthyretin in complex with the compounds revealed that the introduction of chlorine, which is buried in a hydrophobic region, is important for the strong inhibitory effect of the stabilizer against amyloidogenesis. An in vitro absorption, distribution, metabolism and elimination (ADME) study and in vivo pharmacokinetic study demonstrated that the compounds have drug-like features, suggesting that they have potential as therapeutic agents to stabilize transthyretin.
- Kitakami, Ryota,Inui, Kishin,Nakagawa, Yusuke,Sawai, Yurika,Katayama, Wakana,Yokoyama, Takeshi,Okada, Takuya,Kanamitsu, Kayoko,Nakagawa, Shinsaku,Toyooka, Naoki,Mizuguchi, Mineyuki
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- (E)-2-Styrylanthracene-9,10-dione: A new type of fluorescent probe core and its application in specific mitochondria imaging
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Herein, a new type of fluorescent probe core, (E)-2-styrylanthracene-9,10-dione (EK01), was developed which displayed strong fluorescence quantum yield (Φ = 0.867 in DMF; Φ = 0.561 in acetone; Φ = 0.616 in CH2Cl2; Φ = 0.265 in DMSO), good photostability, large stokes shift (90 nm–120 nm) and molar extinction coefficients (0.5875 × 104–0.7609 × 104 mol?1 L cm?1). During cell assays and co-localization experiments, EK01 showed excellent cell membrane permeability and low cytotoxicity against MCF-10A (human mammary epithelial cell line) and HT-29 (human colorectal adenocarcinoma cell line). Particularly, we surprisingly discovered that EK01 could selectively aggregate in mitochondria and specific stain it in a green emissive fluorescent form, which means that EK01 could be a real-time specifically monitor of mitochondria in living cells with a high signal-to-noise ratio. Hence a new mitochondria imaging method was established which is incubating EK01 with living cells for 1 h at a final concentration of 6–12 μM, then visualizing under a confocal microscope at 395 nm. It is worth noting that the fluorescence efficiency of EK01 is not outstanding in organisms, it has much stronger fluorescence efficiency in other organic solvent systems (such as DMF, acetone and CH2Cl2). Therefore, as a new type of fluorescent core that is easy to synthesis and graft, we believe that (E)-2-styrylanthracene-9,10-diones have the potential to develop a variety of fluorescence platforms applying in different fields.
- Lu, Peng-fei,Meng, Fan-hao,Wang, Lin,Wang, Qiu-yin,Wang, Zhao-ran,Zhang, Ting-jian,Zhang, Xu,Zhao, Hai-yang
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- Friedel - gram acylating reaction method based on phthalic anhydride and aromatic alkyl compound
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A part of a substituted alkylbenzene is used as a solvent and a reaction raw material for - gram acylating reaction, a part of a substituted alkylbenzene is dissolved in a reaction raw material phthalic anhydride and a chloroaluminate ionic liquid catalyst, and a residual part of a substituted alkylbenzene is added dropwise - to obtain - (2 - 4' - alkylbenzoyl) benzoic acid intermediate. 2 -position positioning selectivity of the method is higher, and the reaction production cost is low.
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Paragraph 0043-0045
(2021/09/08)
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- Green synthesis method for preparing 2-alkylanthraquinone from phthalic anhydride in one step
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The invention relates to the technical field of green synthesis of organic matters. The invention relates to a synthetic method, in particular to a green synthetic method for preparing 2-alkylanthraquinone from phthalic anhydride in one step. According to the method, phthalic anhydride and alkylbenzene are used as raw materials, difunctional sulfonic acid type solid acid based on an HZSM-5 molecular sieve is used as a catalyst, phthalic anhydride and alkylbenzene are catalyzed to be subjected to a Friedel-Crafts acylation reaction and a dehydration cyclization reaction at the same time under the action of the catalyst, so that the 2-alkyl anthraquinone is prepared in one step, wherein the bifunctional sulfonic acid type solid acid based on the HZSM-5 molecular sieve is a sulfonic acid typeHZSM-5 molecular sieve obtained by carrying out sulfonation treatment on the HZSM-5 molecular sieve. According to the synthesis method of the 2-alkyl anthraquinone, the bifunctional (with strong Bronsted acidity and Lewis acidity) sulfonic acid type solid acid based on the HZSM-5 molecular sieve is used as the catalyst to replace AlCl3 and fuming sulfuric acid, so that generation of a large amount of waste residues, waste gas and wastewater is avoided, and green production is realized.
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Paragraph 0034-0035; 0042-0045
(2020/06/16)
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- Design, Synthesis, Molecular Docking, and Biological Evaluation of New Emodin Anthraquinone Derivatives as Potential Antitumor Substances
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The emodin anthraquinone derivatives are generally used in traditional Chinese medicine due to their various pharmacological activities. In the present study, a series of emodin anthraquinone derivatives have been designed and synthesized, among which 1,3-dihydroxy-6,8-dimethoxyanthracene-9,10-dione is a natural compound that has been synthesized for the very first time, and 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione is a compound that has never been reported earlier. Interestingly, while total seven of these compounds showed neuraminidase inhibitory activity in influenza virus with inhibition rate more than 50 %, specific four compounds exhibited significant inhibition of tumor cell proliferation. The further results demonstrate that 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione showed the best anticancer activity among all the synthesized compounds by inducing highest apoptosis rate to HCT116 cancer cells and arresting their G0/G1 cell cycle phase, through elevation of intracellular level of reactive oxygen species (ROS). Moreover, the binding of 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione with BSA protein has thoroughly been investigated. Altogether, this study suggests the neuraminidase inhibitory activity and antitumor potential of the new emodin anthraquinone derivatives.
- Li, Yuying,Guo, Fang,Chen, Tinggui,Zhang, Liwei,Wang, Zhuanhua,Su, Qiang,Feng, Liheng
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- Tetracyano-anthraquinone dimethane micromolecular receptor material as well as preparation method and application thereof
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The invention relates to a tetracyano-anthraquinone dimethane micromolecular acceptor material as well as a preparation method and application thereof. The structure of the acceptor material is as shown in a formula I, which is described in the specification. The micromolecular acceptor material has good solubility and stability, the absorption spectrum is well matched with the solar spectrum, andthe micromolecular acceptor material can be used for organic solar cells.
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Paragraph 0059; 0066-0068; 0078; 0085-0087
(2020/05/11)
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- Cathodic electroorganic reaction on silicon oxide dielectric electrode
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The faradaic reaction at the insulator is counterintuitive. For this reason, electroorganic reactions at the dielectric layer have been scarcely investigated despite their interesting aspects and opportunities. In particular, the cathodic reaction at a silicon oxide surface under a negative potential bias remains unexplored. In this study, we utilize defective 200-nm-thick n+-Si/SiO2 as a dielectric electrode for electrolysis in an H-type divided cell to demonstrate the cathodic electroorganic reaction of anthracene and its derivatives. Intriguingly, the oxidized products are generated at the cathode. The experiments under various conditions provide consistent evidence supporting that the electrochemically generated hydrogen species, supposedly the hydrogen atom, is responsible for this phenomenon. The electrogenerated hydrogen species at the dielectric layer suggests a synthetic strategy for organic molecules.
- Shin, Samuel J.,Park, Sangmee,Lee, Jin-Young,Lee, Jae Gyeong,Yun, Jeongse,Hwang, Dae-Woong,Chung, Taek Dong
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p. 32939 - 32946
(2021/02/05)
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- Design, synthesis, and molecular docking studies of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives as xanthine oxidase inhibitors
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A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a–j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC50?=?3.0?μm) and the D-phenylalanine derivative 1i (IC50?=?2.9?μm) presented the highest potency and were both more potent than the positive control allopurinol (IC50?=?8.1?μm). Preliminary SAR analysis pointed that an aromatic amino acid fragment, for example, phenylalanine or tryptophan, was essential for the inhibition; the D-amino acid derivative presented equal or greater potency compared to its L-enantiomer; and the 9,10-anthraquinone moiety was welcome for the inhibition. Molecular simulations provided rational binding models for compounds 1d and 1i in the xanthine oxidase active pocket. As a result, compounds 1d and 1i could be promising lead compounds for further investigation.
- Zhang, Ting-Jian,Li, Song-Ye,Yuan, Wei-Yan,Zhang, Yi,Meng, Fan-Hao
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p. 893 - 901
(2018/03/21)
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- Discovery and biological evaluation of some (1H-1,2,3-triazol-4-yl)methoxybenzaldehyde derivatives containing an anthraquinone moiety as potent xanthine oxidase inhibitors
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A series of (1H-1,2,3-triazol-4-yl)methoxybenzaldehyde derivatives containing an anthraquinone moiety were synthesized and identified as novel xanthine oxidase inhibitors. Among them, the most promising compounds 1h and 1k were obtained with IC50values of 0.6?μM and 0.8?μM, respectively, which were more than 10-fold potent compared with allopurinol. The Lineweaver-Burk plot revealed that compound 1h acted as a mixed-type xanthine oxidase inhibitor. SAR analysis showed that the benzaldehyde moiety played a more important role than the anthraquinone moiety for inhibition potency. The basis of significant inhibition of xanthine oxidase by 1h was rationalized by molecular modeling studies.
- Zhang, Ting-jian,Li, Song-ye,Yuan, Wei-yan,Wu, Qing-xia,Wang, Lin,Yang, Su,Sun, Qi,Meng, Fan-hao
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supporting information
p. 729 - 732
(2017/02/18)
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- 2 - substituted - 9, 10 - anthraquinone compound, preparation method and use thereof
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The invention belongs to the technical field of medicine, and particularly relates to 2-substituted-9,10-anthraquinone compounds represented by the general formula I, the general formula II, the general formula III and the general formula IV, and pharmaceutically acceptable salts, hydrates or solvates and pharmaceutically acceptable carriers thereof. A preparation method comprises the steps: with phthalic anhydride as a starting material, carrying out a Friedel-Crafts reaction, concentrated sulfuric acid dehydration, NBS bromization and sodium azide substitution, generating a key intermediate 2-azide methyl-9,10-anthraquinone, and finally in the presence of copper sulfate pentahydrate and vitamin C, carrying out a Husigen cycloaddition reaction with substituted alkyne; or carrying out concentrated sulfuric acid dehydration, cyclization, chromium trioxide oxidation and thionyl chloride chlorination, to obtain anthraquinone-2-formyl chloride, then carrying out an acylation reaction with various L-amino acid methyl esters, further hydrolyzing, and thus obtaining the target compounds. The prepared compounds show good results in in-vitro antitumor activity tests.
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Paragraph 0088-0091
(2017/08/15)
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- Applications of [4+2] Anionic Annulation and Carbonyl-Ene Reaction in the Synthesis of Anthraquinones, Tetrahydroanthraquinones, and Pyranonaphthoquinones
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Hexa-2,5-dienoates, susceptible to isomerization by acids and bases, are suitable for the [4+2] anionic annulation to give 3-(2-alkenyl)naphthoates in regiospecific manner. When combined with intramolecular carbonyl-ene reaction (ICE), the accessibility of the naphthoates culminates in a new synthesis of anthraquinones and diastereoselective synthesis of tetrahydroanthraquinones. This strategy has also resulted in a 3-step synthesis of dehydroherbarin from a 3-methallylnaphthoate.
- Basak, Shyam,Mal, Dipakranjan
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p. 11035 - 11051
(2017/10/27)
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- Full Cleavage of C≡C Bond in Electron-Deficient Alkynes via Reaction with Ethylenediamine
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Reaction of 1,2-diaminioethane (ethylenediamine) with electron-deficient alkynes leads to full scission of the C≡C bond even in the absence of a keto group directly attached to the alkyne. This process involves oxidation of one of the alkyne carbons into C2 of a 2-R-4,5-dihydroimidazole with the concomitant reduction of the other carbon to a methyl group. The sequence of Sonogashira coupling with the ethylenediamine-mediated fragmentation described in this work can be used for selective formal substitution of halogen in aryl halides by a methyl group or a 4,5-dihydroimidazol-2-yl moiety.
- Vasilevsky, Sergei F.,Davydova, Maria P.,Mamatyuk, Victor I.,Tsvetkov, Nikolay,Hughes, Audrey,Baranov, Denis S.,Alabugin, Igor V.
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p. 421 - 429
(2017/04/07)
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- Synthesis method of anthraquinone derivatives and tetracenedione derivatives through benzannulation reaction
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The present invention relates to a method for synthesizing anthraquinone derivatives and tetracene dione derivatives through a benzannulation reaction, which presents a novel synthesis method, capable of processing synthesis easily, conveniently, and efficiently under mild conditions by an organic catalyst. The synthesis method uses an L-proline catalyst which is nontoxic, economical and easily available, compared to conventional production methods, thereby providing the anthraquinone derivatives and the tetracene dione derivatives through the one-pot benzannulation reaction of an α, β-unsaturated aldehyde compound, various 1,4-naphthoquinone compounds or 1,4-anthracenedione compounds. Various forms of anthraquinone derivatives or tetracene dione derivatives prepared by the synthesis method can be widely used for synthesis of natural products, dyes, and pharmaceutical products.COPYRIGHT KIPO 2017
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Paragraph 0029-0030; 0032
(2017/08/09)
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- A 2 - alkyl anthraquinone synthetic method (by machine translation)
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The invention provides a 2 - alkyl anthraquinone synthetic method, the 2 - alkyl anthraquinone synthetic method comprises the following steps: the 2 - (4' - alkyl benzoyl) benzoic acid in the presence of a solvent through the acyl acyl; under the action of the promoter, using anhydrous aluminum ring to carry out the dehydrochlorination; reactant through hydrolysis, liquid separation, pressure reducing desolventizing, drying, to obtain 2 - alkyl anthraquinone. The beneficial effect of the present invention is: not the use of fuming sulfuric acid, mild reaction conditions, acid-free, simple process operation, the product quality is stable, and the yield of the product than the existing production process to improve the 5 - 10%. (by machine translation)
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- Organocatalyzed benzannulation for the construction of diverse anthraquinones and tetracenediones
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An efficient one-pot synthesis of anthraquinones and tetracenediones was achieved vial-proline catalyzed [4+2] cycloaddition of in situ generated azadiene from α,β-unsaturated aldehydes and 1,4-naphthoquinones or 1,4-anthracenedione in good to excellent yield. This protocol constitutes an unprecedented tandem benzannulation that allows one-pot construction of diverse anthraquinones and tetracenediones in the presence of organocatalysts. This methodology was applied successfully to the synthesis of naturally occurring molecules and photochemically interesting phenanthrenequinone derivatives.
- Somai Magar, Krishna Bahadur,Xia, Likai,Lee, Yong Rok
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supporting information
p. 8592 - 8595
(2015/05/20)
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- Synthesis and characterization of highly soluble blue emitting poly(2-vinylanthracene) with 9,10-di(2-naphthalenyl) and 9,10-di(3-quinolinyl) substituents
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Two new blue fluorescent polymers poly(910-di(2-naphthalenyl)-2- vinylanthracene) (P(2ADN)) and poly(9,10-di(3-quinolinyl)-2-vinylanthracene) (P(3ADQ)), were polymerized from free radical solution addition polymerization with Mn = 21,500 and 15,400, respectively. The polymers are highly soluble in common organic solvents while P(3ADQ) is also soluble in polar solvents including a 1/1 mixture of ethanol/water. Both polymers are amorphous with excellent thermal stability (Tg (Midpoint) = 343 C and 298 C for P(2ADN) and P(3ADQ), respectively). P(2ADN) exhibited three prominent absorption bands in tetrahydrofuran (364, 383 and 403 nm) and is similar to that of P(3ADQ) (369, 384 and 404 nm). The solid-state Commission Internationale d'Eclairage (CIEx,y) color coordinates for illumination were (0.15, 0.10) for P(2ADN) and (0.15, 0.13) for P(3ADQ) which lied within the requirements for a true blue display color. The photoluminescence (PL) of the polymers red-shifted 16-17 nm from their respective pendant chromophore 2-methyl-9,10-di(2-naphthalenyl)anthracene (2MADN) and 2-methyl-9,10-di(3- quinolinyl)anthracene (3MADQ) and can be attributed to partial π-π stacking between the adjacent aromatic pendant groups in the polymer chains. The luminescences of 3MADQ and P(3ADQ) are sensitive to pH and the pKa for the alkalescent 3MADQ and P(3ADQ) calculated was 2.4 and 2.7, respectively. Both polymers have similar band-gap energy (Eg) between 2.88 and 2.91 eV, while the LUMO/HOMO for P(3ADQ) is shifted slightly downward -0.06 to -0.03 eV compared to P(2ADN). The mobility (μhole) of the two polymers were measured to be 4.0 × 10-7 and 10-8 cm 2/(V-s) for P(2ADN) and P(3ADQ), respectively.
- Wang, Jianli,Leung, Louis M.
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p. 105 - 115
(2013/10/21)
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- Nitrous oxide oxidation catalyzed by ruthenium porphyrin complex
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Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200°C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.
- Tanaka, Hirotaka,Hashimoto, Kentaro,Suzuki, Kyosuke,Kitaichi, Yasunori,Sato, Mitsuo,Ikeno, Taketo,Yamada, Tohru
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p. 1905 - 1914
(2007/10/03)
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- Selective nitrous oxide oxidation for C-H oxidation and aromatization of 9,10-dihydroanthracene derivatives
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During the nitrous oxide oxidation of 9,10-dihydroanthracene derivatives catalyzed by the ruthenium-porphyrin complexes, anthraquinones were selectively afforded by the C-H oxidation of the benzylic carbon under the appropriate reaction conditions, whereas anthracenes as a result of oxidative aromatization were selectively obtained in the presence of sulfuric acid.
- Hashimoto, Kentaro,Tanaka, Hirotaka,Ikeno, Taketo,Yamada, Tohru
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p. 582 - 583
(2007/10/03)
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- Photophysical and photochemical processes of 2-methyl, 2-ethyl, and 2-tert-butylanthracenes on silica gel. A substituent effect study
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PAH are organic pollutants formed and released into the environment by the incomplete combustion of fossil fuel, coal, wood, gas, oil, garbage, tobacco, and charbroiled meat. The photophysics and photochemistry of 2-methylanthracene (2MA), 2-ethylanthracene (2EA), and 2-tert-butylanthracene (2TBA) adsorbed on silica were studied at a silica/air interface. 2MA, 2EA, and 2TBA showed no evidence of ground state pairing even at high surface coverages, and crystallized on the surface at higher surface coverages. The photolysis of 2MA, 2EA, and 2TBA at a silica/air interface proceeded more efficiently than the photolysis of anthracene, to produce the corresponding 9,10-endoperoxides formed by the addition of singlet molecular oxygen (type II) to the ground state molecules. At low surface coverages, no evidence of any dimer was observed in photolyzed 2MA, 2EA, and 2TBA samples. A small amount of dimers (isomeric) were observed at higher surface coverages, suggesting that the crystal forms of these molecules may be involved in the dimerization process. The photolysis rate decreased with increasing surface coverage, due to an inner effect induced by crystal formation. Photolysis rate decreased by an order of magnitude in the presence of 1 monolayer of physisorbed water. Time-resolved transient studies of excited triplet states of 2MA, 2EA, and 2TBA showed that triplet lifetimes were shortened on wet silica. The efficiency of singlet molecular oxygen formation significantly decreased on wet silica. These results indicated that decreased photolysis rate was caused by reduced singlet quantum yield in the presence of physisorbed water.
- Dabestani, Reza,Higgin, Jashua,Stephenson, Daniel,Ivanov, Ilia N.,Sigman, Michael E.
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p. 10235 - 10241
(2007/10/03)
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- Efficient photodecarboxylation of aroyl-substituted phenylacetic acids in aqueous solution: A general photochemical reaction
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Photolysis (254-350 nm) of a variety of aroyl-substituted phenylacetic acids and p-acetylphenylacetic acid in aqueous solution at pH > pK(a) resulted in efficient photodecarboxylation (Φ = 0.2-0.7), to give in most cases a single product arising via the corresponding arylmethyl carbanion, indicating that photodecarboxylation is an efficient and general reaction for these types of compounds.
- Xu,Wan
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p. 2147 - 2148
(2007/10/03)
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- Photoinduced electron transfer from excited [tris(2,2'- bipyridine)ruthenium(II)]2+ to a series of anthraquinones with small positive or negative Gibbs energy of reaction. Marcus behavior and negative activation enthalpies
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In the electron transfer (ET) quenching reactions of electronically excited *Ru(bpy)32+ in acetonitrile an increase of the rate constant k(q) is observed in the series of 2-methyl-, 1-chloro-, and 1-nitro-anthraquinone as quenchers. If alkali salts are used as supporting electrolytes the AQ·- radical anions are found to form specific associates with the alkali cations. In the presence of non-associating tetraalkylammonium salts the system follows the predictions of Marcus theory. Numerical methods are developed which allow the determination of the rate constants of the conventional reaction scheme. This analysis shows that the quantum yield of free AQ*- radical anion formation is governed by the interplay of forward, reverse and back ET. Negative activation enthalpies are found for the activation controlled quenching reactions. From the numerical analysis of the system of rate constants it is inferred that this phenomenon is due to the elementary ET step in the reaction sequence. We discuss the pre-equilibrium and elementary reaction models for reactions with negative activation enthalpy and present, to our knowledge, the first example of successful discrimination between them.
- Frank, Rudolf,Greiner, Gerhard,Rau, Hermann
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p. 3481 - 3490
(2007/10/03)
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- Orthobromodiphenylmethane derivatives as starting materials for the total synthesis of anthraquinones
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In this communication we describe the synthesis of four simple anthraquinones by a five-step sequence, using easily available bromobenzaldehydes and phenyllithium derivatives as starting materials.
- Almeida, Wanda P.,Costa, Paulo R.R.
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p. 4507 - 4518
(2007/10/03)
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- Comparison of spin density calculation methods for various alkyl-substituted 9,10-anthraquinone anion radicals in the solution phase
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EPR and ENDOR spectra were recorded for 2-methyl-9,10-anthraquinone (2-methylAQ), 2-ethylAQ, 2-tertbutylAQ and 2,3-dimethylAQ anion radicals in the solution phase. The EPR spectra were simulated with the help of ENDOR data. The experimental isotropic hyperfine coupling constants (IHFCs) were compared with calculated values from semi-empirical INDO, spin-restricted AM1/CI and B3PW91 density-functional methods. The best computational methods for the IHFCs were the semi-empirical AM1/CI method and the B3PW91 density-functional method with a large basis set.
- Eloranta, Jussi,Vatanen, Virpi,Groenroos, Antti,Vuolle, Mikko,Maekelae, Reijo,Heikkilae, Hilkka
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p. 898 - 902
(2007/10/03)
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- Use of thiazyl chlorides, alkyl carbamates, and thionyl chloride to fuse 1,2,5-thiadiazoles to quinones and to oxidize, chlorinate, and aminate them
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Thiazyl chlorides in a simple one-step procedure fuse 1,2,5-thiadiazole rings to quinones. So do alkyl carbamates mixed with excess thionyl chloride and pyridine. Evidence is put forward to support the hypothesis that NSCl or a related thiazyl derivative is the reactive species that brings about the transformations. Selenoyl chloride mixed with an alkyl carbamate, pyridine, and quinones similarly gives 1,2,5-selenodiazoloquinones. Thionyl chloride in pyridine chlorinates quinones and oxidizes hydroquinones. 2,3-Dichloro-1,4-quinones with S4N4 or with alkyl N-sulfinylcarbamates give 1,2,5-thiadiazoloquinones. Quinones and their 2,3-dichloro derivatives with TsNSO in pyridine give betaine derivatives of 2,3-diaminoquinones, which pyrrolidine converts into 2-amino-3-(tosylamino)quinones. A unified set of mechanisms is presented that accounts for these transformations.
- Shi,Katz,Yang,Liu
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p. 1285 - 1297
(2007/10/02)
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- INVESTIGATION OF THE COMPOSITION OF PETROLEUM ANTHRACENE HYDROCARBONS
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The optimum conditions of adduct formation with maleic anhydride for the isolation of ca. 100percent anthracene hydrocarbons from a mixture with phenanthrenes and other compounds are set out.Gas-liquid chromatography has been used to study the individual composition of anthracene and C1-C3 anthracenes isolated by the method proposed from concentrates of triaromatic hydrocarbons of crude oils from the Okha, Katangli (Sakhalin) and Dorokhovsk (Urals-Volga) fields.With the aid of the individual compounds synthesized, for the first time 2-ethylanthracene and 1,3- and 2,3-dimethylanthracene have been identified in crude oils, and the retention indices have also been calculated for certain C2- and C3-substituted anthracene hydrocarbons for chromatographic phase SE-54.
- Ivanov, V. I.,Golovko, A. K.
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p. 504 - 512
(2007/10/02)
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- Process for preparation of 2-substituted 1,4-naphthoquinone
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A process for preparation of a 2-substituted-1,4-naphthoquinone which comprises oxidizing a 2-substituted naphthalene to obtain reaction products comprising a 2-substituted-1,4-naphthoquinone and a 6-substituted-1,4-naphthoquinone; adding a diene compound to the reaction products and heating the mixture to form a Diels-Alder reaction adduct between the diene compound and the 6-substituted-1,4-naphthoquinone in the reaction products; and separating the 2-substituted-1,4-naphthoquinone from the adduct.
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- S(RN)1 reactions of anthraquinone alkylating agents
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The C-alkylation reaction of three reductive alkylating agents prepared from 2-methylanthraquinone by 2-nitropropane anion is shown to proceed by the S(RN)1 mechanism. The S(RN)1 mechanism is confirmed by the leaving group effect and the inhibitory effect of dioxygen, p-dinitrobenzene, cupric chloride and di-tert-butylnitroxide. This reaction can be extended to 1-methyl-3-nitropyrolidin-2-one anion.
- Crozet,Vanelle,Jentzer,Donini,Maldonado
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p. 11253 - 11262
(2007/10/02)
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- Condensation catalyst and catalytical condensation process for organic carboxylic anhydrides
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A condensation reaction catalyst useful for producing an organic compound, for example, anthraquinone compounds from phthalic dianhydride and optionally benzene, comprises a catalytic principal component consisting of a solid acid substance, for example, compound oxides or zeolite, and an additional basic component consisting of ammonia or a volatile organic base, for example, isopropylamine, n-butylamine, or pyridine, and attached to at least strong acid sites of the solid acid substance.
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- Obtention of anthraquinones by selective oxidation of the corresponding anthracenes and 9,10-dimethoxyanthracenes with copper or zinc nitrate supported on silica gel
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Anthracene, 9,10-dimethoxyanthracene and substituted analogues are selectively oxidized to the corresponding anthraquinones in good yields by copper(II) or zinc(II) nitrate supported on silica gel; the ether groups at different position from 9 and 10 are unaffected.
- Anastasia,Allevi,Bettini,Fiecchi,Sanvito
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p. 1083 - 1084
(2007/10/02)
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- N.M.R. Study of Bond Orders in o- and p-Quinones
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The 4J(Me-CC-H) coupling constsnt, previously established as a probe of bond order,1-3 was used to examine bond orders in a number of quinones.It was found that the presence of a quinone moiety does not cause bond localization in aromatic rings adjacent to the quinone ring.
- Gready, Jill E.,Hata, Kazumi,Sternhell, Sever,Tansey, Charles W.
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p. 593 - 600
(2007/10/02)
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- Regiospecific Addition of Monooxygenated Dienes to Halo Quinones
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In spite of their decreased polarity with respect to previously studied electron-rich analogues, monooxygenated dienes also react regiospecifically with halo quinones.The corresponding adducts can easily be aromatized on silica gel to isomeric polysubstituted naphthoquinones of unambiguous structure and therefore provide ready access to substrates for subsequent regiospecific annulations.The scope of this approach is illustrated by advantageous syntheses of several natural products: chimaphilin, 6-methylalizarin, 6-methylxantopurpurin, and barleriaquinone.The adductscan also give rise to a series of products in which the oxygen function of the dienes is preserved as a hydroxyl group in the quinone.To this end adducts derived from 1-oxygenated dienes and halo quinones were oxidized effectively with Jones reagent while those obtained from the 2-oxygenated isomers responded better to manganese dioxide.Relative positions of substituens in the adducts were readily confirmed by comparison of some of the hydroxylated oxidation products with known compounds of unambiguous structure.The method is again illustrated by the ready synthesis of a number of natural products including plumbagin, soranjidiol, isochrysophanol and its 8-methyl ether, and isozyganein and its 5-methyl ether.
- Boisvert, Louise,Brassard, Paul
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p. 4052 - 4059
(2007/10/02)
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- The Influence of Ion Pairing on the Electroreductive Cleavage of Substituted 9,10-Antraquinones in DMF Solution
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A variety of substituted 9,10-antraquinones with acetates and trifluoroacetates leaving groups at the 2-methyl position were synthesized from 2-methyl-9,10-antraquinones containing 0-2 methoxy substituents.Cyclic voltammograms of the acetates in DMF containing LiClO4 as supporting electrolyte exhibited two reduction waves, the first resulting from the formation of Li(1+) ion pairs of their radical anions and the second from Li(1+) ion pairs of their dianions.Constant potential reduction of the acetates to their dianions followed by air oxidation gave high yields (78-88percent) of their reductive cleavage products, the 2-methyl-9,10-anthraquinones.In contrast, reduction of the acetates to their radical anions led to high yields of their alcohols (the 2-(hydroxymethyl)-9,10-anthraquinones) as a result of saponification.Reduction of the trifluoroacetates in DMF/LiClO4 produced comparable yields of their corresponding reductive cleavage products and alcohols via ion pairs of their radical anions or dianions.
- Blankespoor, Ronald L.,Schutt, David L.,Tubergen, Melinda B.,De Jong, Randy L.
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p. 2059 - 2064
(2007/10/02)
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- REACTIONS DE SUBSTITUTION SRN1 EN SERIE QUINONIQUE
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Salts derived from 2-nitropropane react with 2-(halomethyl)-9,10-anthracenedione or triethylammonium derivative by a SRN1 mechanism.The operation of this mechanism is confirmed by the leaving group effect and by the inhibitory effect of di-tert-butylnitroxide.A base-promoted nitrous acid elimination gives a 9,10-anthracenedione bearing a trisubstituted ethylenic double bound in the 2 position.
- Crozet, Michel P.,Jentzer, Olivier,Vanelle, Patrice
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p. 5531 - 5534
(2007/10/02)
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- Cycloaddition Reactions of Citral Dienamines with 1,4-Quinones
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Cycloaddition reactions of citral dienamines (Ia and Ib) with different 1,4-quinones have been investigated and the products formed are characterized.The unusual elimination of isopentenyl side chain during the Diels-Alder reaction of dienamine (Ia or Ib) with quinones, has been found to be consistent.Aromatisation seems to be the driving force for the elimination which involves cleavage of C - C bond under relatively mild condition.Results obtained in the attempted total synthesis of Va, a regioisomer of compound (V), one of the products obtained in the reaction of Ia with p-benzoquinone, are also presented.
- Ekkundi, Vadiraj S.,Trivedi, G. K.
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p. 360 - 364
(2007/10/02)
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- A NOVEL REGIOSPECIFIC INTRAMOLECULAR CYCLOADDITION OF AN AROMATIC RING. MOLECULAR ORBITAL STUDY OF CONJUGATED KETENES THERMALLY GENERATED FROM SIX-MEMBERED α-MONOCARBONYL AZO-COMPOUNDS
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When a methylene dichloride solution containing 4,4-diarylphthalazin-1(4H)-one (3) was warmed above -50 deg C, nitrogen extrusion occurred to result in the formation of the quinonoid ketene (19).The quinonoid ketene thus generated underwent a facile and regiospecific intramolecular ?4a + ?2a> cycloaddition with NN-dimethylaniline to afford a norcaradiene (22), followed by ring opening to an azulenone derivative (14).It was found, however, that this process takes place only with an aromatic ring bearing strong electron-donating substituents such as dialkylamino groups.FMO analyses based on the model system calculated by the CNDO/2 method showed that the dominant HOMO-LUMO interaction in the transition state should involve the HOMO of NN-dialkylaniline and LUMO of the quinonoid ketene.Thus, the in-plane ?*-orbital induces the orthogonal approach of the two components favouring an antarafacial pathway and the cyclisation is initiated by preferential bond formation between the central carbon of the ketene moiety and the para-carbon of NN-dialkylaniline to result in the formation of (22).
- Kuzuya, Masayuki,Miyake, Fumio,Okuda, Takachiyo
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p. 1471 - 1478
(2007/10/02)
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- SYNTHESIS OF ξ-PYRROMYCINONE, 7-DEOXYAURAMYCINONE, AND 7-DEOXYAKLAVINONE VIA KETOESTER CYCLIZATION
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7,10-O-Dimethyl-ξ-pyrromycinone (78) and the not naturally occurring 7-deoxyanthracyclinones 76 and 77 are prepared via base induced cyclization of the ketoesters 73-75, and stereoselectively hydroxylated to the 2,4-cis diols 83 and 85.
- Krohn, Karsten,Klimars, Michael,Koehle, Hans-Juergen,Ebeling, Eckehardt
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p. 3677 - 3694
(2007/10/02)
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- Reagents and synthetic methods 41: oxidations with chromium trioxide under the influence of crown ethers
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An unusual new application of crown ethers in organic synthesis is described.Chromium trioxide, in the presence of crown ether as catalyst, in dichloromethane as solvent, was found an efficient oxidizing system for the chemoselective oxidation of mercaptans to disulfides.It is also highly efficient for the oxidation of hydroquinones to the corresponding benzoquinones in almost quantitative yield.A high conversion of polynuclear hydrocarbons into quinones in acetic acid media is also briefly described.
- Juaristi, M.,Aizpurua, J. M.,Lecea, B.,Palomo, C.
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p. 2941 - 2944
(2007/10/02)
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- Photoenolisation. XI. Photooxydation des o-methylbenzophenones
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Photoenols 2 of 2- (1a), 2,4- (1b), 2,5- (1c), 2,6- (1d), 2,2'- (1e) and 2,3'-dimethylbenzophenones (1f) were trapped by (3)O2.When a 350 nm wavelength Hg lamp (Rayonet RPR 100) was used (benzene solution) with ketones 1a-c, the corresponding 2-formyl- 4 and 2-carboxybenzophenones 8 were formed as well as 3-phenyl-phtalides 10.Compounds 4 arose from dehydration of the intermediate endoperoxydes 3.Throught photoenolisation, 2-formylbenzophenones 4 gave the intermediate ketene-enols 5 which either isomerised to phtalides 10 or added oxygen to form the corresponding endoperoxydes 6; the latter isomerised to peracids 7, which, by reaction with aldehydes 4, yielded the carboxylic acids 8.When the aerated irradiations were performed simultaneously with 350 nm light and with light above 380 nm (Hanovia 679 A-36, benzene solution), ketones 1a-f yielded the same compounds 4, 8 and 10 but also anthraquinones 13.The latter arose from reversible cyclisation of photoenols 2 E giving dihydroanthranols 11 which were trapped by oxygen, yielding the anthrones 12 which were subsequently photooxidized to anthraquinones 13.With 2,6-dimethylbenzophenone (1d), the corresponding photoenols 2 were trapped for the first time.Compounds 8d, and 13d were absent, but instead 1-carboxyanthraquinone 15 was obtained.The latter can arise from 1-methylanthraquinone 13d trough photoenolisation-oxidation process alredy reported for this compound.With 2,2'-dimethylbenzophenone 1e, 3,3'-spirobiphtalide 14 was obtained instead 2-methyl-2'-carboxybenzophenone 8e; the latter, through a photoenolisation-oxidation process analogous to that described in the second paragraph, yielded 2,2'-dicarboxybenzophenone which underwent dehydration to compound 14.Under the same conditions (Hanovia) but in acetic acid solution, anthraquinones 13 were not formed with ketones 1a-f, due to rapid reketonisation of photoenols 2 E in this medium; however, compounds 4, 8, 10 and 14 were produced.Products 8, 10, 13, 14 and 15 were isolated and characterised or identified.Yields were deduced from actual weights of the isolated compounds (carboxylic acids 8 and 15) and from GLC determinations (compounds 4, 10, 13 and 14).
- Pfau, Michel,Molnar, James,Heindel, Ned D.
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p. 164 - 169
(2007/10/02)
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- REGIOSPECIFIC ADDITIONS OF SOME SIMPLE DIENES TO HALOQUINONES
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Some simple dienes have been shown to react regiospecifically with haloquinones; the adducts can be oxidized without loss of the oxygenated function or aromatized to a variety of natural products and useful intermediates.
- Boisvert, Louise,Brassard, Paul
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p. 2453 - 2456
(2007/10/02)
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- Rh-CATALYZED OXIDATION OF ANTHRACENES TO ANTHRAQUINONES USING t-BUTYLHYDROPEROXIDE
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Rh-catalyzed oxidation of 2-substituted anthracene with t-butylhydroperoxide affords anthraquinones in yields up to 90percent, while V-catalyzed oxidation and stoichiometric oxidation with CrO3 are less efficient.
- Mueller, Paul,Bobillier, Christiane
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p. 5499 - 5500
(2007/10/02)
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- Process for the preparation of anthraquinone and its substituted derivatives
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A process for the preparation of anthraquinone compounds by condensation of phthalic anhydride with a benzene derivative wherein a mixture of hydrofluoric acid and boron trifluoride is utilized as catalyst.
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- A New Route to Anthraquinones
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The lithium salts derived from position 3 of phthalides react with arynes to form adducts, which, upon aerial oxidation, produce anthraquinones in moderate to good yields.Substituted phthalides and arynes also participate in this general reaction.The addition to unsymmetrically substituted arynes shows regioselectivity, whilst the availability of a new general route to phthalides extends the scope of this reaction.
- Dodsworth, David J.,Calcagno, Maria-Pia,Ehrmann, E. Ursula,Devadas, Bhatt,Sammes, Peter G.
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p. 2120 - 2124
(2007/10/02)
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