- Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
-
As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
- Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
-
supporting information
p. 8040 - 8046
(2021/11/01)
-
- Practical and Selective sp3 C?H Bond Chlorination via Aminium Radicals
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The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine-tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site-selective chlorination of sp3 C?H bonds. This process exploits the ability of protonated N-chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical-chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H-atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3 C?H chlorination.
- McMillan, Alastair J.,Sieńkowska, Martyna,Di Lorenzo, Piero,Gransbury, Gemma K.,Chilton, Nicholas F.,Salamone, Michela,Ruffoni, Alessandro,Bietti, Massimo,Leonori, Daniele
-
supporting information
p. 7132 - 7139
(2021/03/03)
-
- Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
-
Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
- Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
-
p. 3685 - 3690
(2021/05/31)
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- A preparing method of diethylamino hydroxybenzoyl hexylbenzoate
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The present invention relates to a method for the preparation of diethylamino hydroxybenzoyl hexyl benzoate. Specifically, the present invention relates to a method for preparing diethylamino hydroxybenzoyl hexyl benzoate which is easy to manufacture and commercially available in mass production, and diethylamino hydroxybenzoyl hexyl benzoate crystalline particles prepared thereby. According to the present invention, diethylamino hydroxybenzoyl hexyl benzoate crystalline particles having excellent UV blocking effect can be obtained in a stable and high yield.COPYRIGHT KIPO 2020
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-
Paragraph 0069-0071
(2020/03/28)
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- Supported palladium membrane reactor architecture for electrocatalytic hydrogenation
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Electrolytic palladium membrane reactors offer a means to perform hydrogenation chemistry utilizing electrolytically produced hydrogen derived from water instead of hydrogen gas. While previous embodiments of these reactors employed thick (≥25 μm) palladium foil membranes, we report here that the amount of palladium can be reduced by depositing a thin (1-2 μm) layer of palladium onto a porous polytetrafluoroethylene (PTFE) support. The supported palladium membrane can be designed to ensure the fast diffusion of reagent and hydrogen to the palladium layer. The hydrogenation of 1-hexyne, for example, shows that the supported Pd/PTFE membrane can achieve reaction rates (e.g., 0.71 mmol h-1) which are comparable to 0.92 mmol h-1 measured for palladium membranes with a high-surface area palladium electrocatalyst layer. The root cause of these comparable rates is that the high porosity of PTFE enables a 12-fold increase in electrocatalytic surface area compared to planar palladium foil membranes. These results provide a pathway for designing a cost-effective and potentially scalable electrolytic palladium membrane reactor.
- Delima, Roxanna S.,Sherbo, Rebecca S.,Dvorak, David J.,Kurimoto, Aiko,Berlinguette, Curtis P.
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p. 26586 - 26595
(2019/12/04)
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- Experimental and theoretical studies of a greener catalytic system for saturated hydrocarbon chlorination composed by trichloroisocyanuric acid and a copper(II) compound
-
We are describing herein a new environmentally friendly catalytic system able to convert cyclohexane to chlorocyclohexane with 100% selectivity. The method was also applied to the chlorination of n-hexane and adamantane. The catalytic system employs thichloroisocyanuric acid (TCCA) as halogenating agent and a mononuclear copper(II) complex [Cu(BPAH)(H2O)](ClO4)2, 1, as catalyst (BPAH = 1,4-bis(propanamide)homopiperazine), whose molecular structure was solved by monocrystal X-ray diffraction. For cyclohexane, at a ratio catalyst:substrate:TCCA of 1:1000:333, the system reached a conversion of 32.0 ± 1% at 25 °C and 44.7 ± 0.4% at 50 °C, with 100% selectivity for chlorocyclohexane. With n-hexane, a similar conversion was observed at 50 °C, resulting in mixture of monochlorides. Employing adamantane as substrate, the isomers 1-chloroadamantane and 2-chloroadamante were preferentially formed, together with traces of dichloroadamantane. EPR and ESI-(+)-MS analyses indicate the formation of a Cu-hypochlorite intermediate species, which is supported by theoretical calculations.
- Melo, Isis L.,Lube, Leonardo M.,Neves, Eduardo S.,Terra, Wagner S.,Fernandes, Christiane,Matos, Carlos R.R.,Franco, Roberto W.A.,Resende, Jackson A.L.C.,Valente, Daniel C.A.,Horta, Bruno A.C.,Cardozo, Thiago M.,Horn, Adolfo
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p. 150 - 158
(2018/06/14)
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- Reagent-dictated site selectivity in intermolecular aliphatic C-H functionalizations using nitrogen-centered radicals
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The site selectivities of intermolecular, aliphatic C-H bond functionalizations are central to the value of these transformations. While the scope of these reactions continues to expand, the site selectivities remain largely dictated by the inherent reactivity of the substrate C-H bonds. Herein, we introduce reagent-dictated site selectivity to intermolecular aliphatic C-H functionalizations using nitrogen-centered amidyl radicals. Simple modifications of the amide lead to high levels of site selectivity in intermolecular C-H functionalizations across a range of simple and complex substrates. DFT calculations demonstrate that the steric demand of the reacting nitrogen-centered radical is heavily affected by the substitution pattern of the starting amide. Optimization of transition state structures consistently indicated higher reagent-dictated steric selectivities using more hindered amides, consistent with experimental results.
- Carestia, Anthony M.,Ravelli, Davide,Alexanian, Erik J.
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p. 5360 - 5365
(2018/06/27)
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- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
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The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
- Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
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p. 4729 - 4737
(2018/10/23)
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- Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature
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A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H2O/CF3CH2OH at room temperature. Other secondary and primary alkyl sp3 C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp3 C-H bond or the aryl sp2 C-H bond of toluene.
- Zhao, Mengdi,Lu, Wenjun
-
supporting information
p. 4560 - 4563
(2017/09/11)
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- Hydrogen Chloride Gas in Solvent-Free Continuous Conversion of Alcohols to Chlorides in Microflow
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Chlorides represent a class of valuable intermediates that are utilized in the preparation of bulk and fine chemicals. An earlier milestone to convert bulk alcohols to corresponding chlorides was reached when hydrochloric acid was used instead of toxic and wasteful chlorinating agents. This paper presents the development of an intensified solvent-free continuous process by using hydrogen chloride gas only. The handling of corrosive hydrogen chloride became effortless when the operating platform was split into dry and wet zones. The dry zone is used to deliver gas and prevent corrosion, while the wet zone is used to carry out the chemical transformation. The use of gas instead of hydrochloric acid allowed a decrease in hydrogen chloride equivalents from 3 to 1.2. In 20 min residence time, full conversion of benzyl alcohol yielded 96 wt % of benzyl chloride in the product stream. According to green chemistry and engineering principles, the developed process is of an exemplary type due to its truly continuous nature, no use of solvent and formation of water as a sole byproduct.
- Borukhova, Svetlana,No?l, Timothy,Hessel, Volker
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supporting information
p. 568 - 573
(2016/03/04)
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- Continuous-Flow Multistep Synthesis of Cinnarizine, Cyclizine, and a Buclizine Derivative from Bulk Alcohols
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Cinnarizine, cyclizine, buclizine, and meclizine belong to a family of antihistamines that resemble each other in terms of a 1-diphenylmethylpiperazine moiety. We present the development of a four-step continuous process to generate the final antihistamines from bulk alcohols as the starting compounds. HCl is used to synthesize the intermediate chlorides in a short reaction time and excellent yields. This methodology offers an excellent way to synthesize intermediates to be used in drug synthesis. Inline separation allows the collection of pure products and their immediate consumption in the following steps. Overall isolated yields for cinnarizine, cyclizine, and a buclizine derivative are 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1. The incredible bulk: Bulk alcohols are converted continuously into chlorides using HCl in a microflow. A reaction network that consists of four steps and two inline separations leads to the continuous preparation of cinnarizine, cyclizine, and a buclizine derivative with yields of 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1.
- Borukhova, Svetlana,Nol, Timothy,Hessel, Volker
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- Site-Selective Aliphatic C-H Chlorination Using N-Chloroamides Enables a Synthesis of Chlorolissoclimide
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Methods for the practical, intermolecular functionalization of aliphatic C-H bonds remain a paramount goal of organic synthesis. Free radical alkane chlorination is an important industrial process for the production of small molecule chloroalkanes from simple hydrocarbons, yet applications to fine chemical synthesis are rare. Herein, we report a site-selective chlorination of aliphatic C-H bonds using readily available N-chloroamides and apply this transformation to a synthesis of chlorolissoclimide, a potently cytotoxic labdane diterpenoid. These reactions deliver alkyl chlorides in useful chemical yields with substrate as the limiting reagent. Notably, this approach tolerates substrate unsaturation that normally poses major challenges in chemoselective, aliphatic C-H functionalization. The sterically and electronically dictated site selectivities of the C-H chlorination are among the most selective alkane functionalizations known, providing a unique tool for chemical synthesis. The short synthesis of chlorolissoclimide features a high yielding, gram-scale radical C-H chlorination of sclareolide and a three-step/two-pot process for the introduction of the β-hydroxysuccinimide that is salient to all the lissoclimides and haterumaimides. Preliminary assays indicate that chlorolissoclimide and analogues are moderately active against aggressive melanoma and prostate cancer cell lines.
- Quinn, Ryan K.,K?nst, Zef A.,Michalak, Sharon E.,Schmidt, Yvonne,Szklarski, Anne R.,Flores, Alex R.,Nam, Sangkil,Horne, David A.,Vanderwal, Christopher D.,Alexanian, Erik J.
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supporting information
p. 696 - 702
(2016/02/03)
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- Direct Reduction of 1-Bromo-6-chlorohexane and 1-Chloro-6-iodohexane at Silver Cathodes in Dimethylformamide
-
Cyclic voltammetry and controlled-potential (bulk) electrolyses have been employed to probe the electrochemical reductions of 1-bromo-6-chlorohexane and 1‐chloro-6-iodohexane at silver cathodes in dimethylformamide (DMF) containing 0.050?M tetra-n-butylammonium tetrafluoroborate (TBABF4). A cyclic voltammogram for reduction of 1-bromo-6-chlorohexane shows a single major irreversible cathodic peak, whereas reduction of 1-chloro-6-iodohexane gives rise to a pair of irreversible cathodic peaks. Controlled-potential (bulk) electrolyses of 1-bromo-6-chlorohexane at a silver gauze cathode reveal that the process involves a two-electron cleavage of the carbon–bromine bond to afford 1-chlorohexane as the major product, along with 6-chloro-1-hexene, n‐hexane, 1‐hexene, and 1,5-hexadiene as minor species. In contrast, bulk electrolyses of 1-chloro-6-iodohexane indicate that the first voltammetric peak corresponds to a one-electron process, leading to production of a dimer (1,12-dichlorododecane) together with 1-chlorohexane and 6-chloro-1-hexene as well as 1‐hexene and 1,5-hexadiene in trace amounts. At potentials corresponding to the second cathodic peak, reduction of 1-chloro-6-iodohexane is a mixture of one- and two-electron steps that yields the same set of products, but in different proportions. Mechanistic schemes are proposed to explain the electrochemical behavior of both 1‐bromo-6-chlorohexane and 1-chloro-6-iodohexane.
- Rose, John A.,McGuire, Caitlyn M.,Hansen, Angela M.,Karty, Jonathan A.,Mubarak, Mohammad S.,Peters, Dennis G.
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p. 311 - 317
(2016/10/05)
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- Use of metal-accumulating plants for implementing chemical reactions
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The use of metal-accumulating plants for implementing chemical reactions.
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Page/Page column 38-40
(2015/10/28)
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- Continuous flow synthesis of n-alkyl chlorides in a high-temperature microreactor environment
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Applying continuous flow processing in a high-temperature/high-pressure regime, n-alkyl chlorides can be prepared in high yields and selectivity by direct uncatalyzed chlorodehydroxylation of the corresponding n-alcohols with 30% aqueous hydrochloric acid. Optimum conditions for the preparation of n-butyl and n-hexyl chloride involve the use of a glass microreactor chip, a reaction temperature of 160-180 C (20 bar backpressure) and a residence time of 15 min.
- Reichart, Benedikt,Tekautz, Guenter,Kappe, C. Oliver
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p. 152 - 157
(2013/03/13)
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- Chlorination of hydrocarbons with CCl4 catalyzed by complexes of Mn, Mo, V, Fe
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Catalytic chlorination of alkanes, cycloalkanes, and adamantane utilizing tetrachloromethane as the source of chlorine and applying catalysts containing manganese, molybdenum, vanadium, and iron activated with nitrile ligands, alcohols, and water was fulfilled. The optimum ratios of catalysts and reagents and the best reaction conditions were found for selective synthesis of chlorine-substituted hydrocarbons derivatives. Pleiades Publishing, Ltd., 2013.
- Khusnutdinov,Shchadneva,Bayguzina,Oshnyakova,Mayakova,Dzhemilev
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p. 1557 - 1566
(2014/02/14)
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- 19F NMR of linear N,N-difluoroaminoalkanes
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Whereas most N,N-difluoroaminoalkanes exhibit a single 19F resonance at about +50 ppm, the tri-component mixtures of both N,N-difluoroaminopentanes and N,N-difluoroaminohexanes exhibited a more complex pattern. The individual 1-N,N-difluoroamino-, 2-N,N-difluoroamino- and 3-N,N-difluoroaminopentanes have been synthesized and their separated resonances are reported.
- Belter, Randolph K.
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body text
p. 73 - 76
(2012/05/07)
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- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
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In continuation of research to explore the applied potential of DMF-like ionic liquid, the ionic liquid version of N,N-dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF-like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF-like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF-like ionic liquid has been coined that is DMF-like "multipurpose" ionic liquid. Copyright
- Hullio, Ahmed Ali,Mastoi
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scheme or table
p. 1647 - 1657
(2012/09/21)
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- Reactivity of anionic nucleophiles in ionic liquids and molecular solvents
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The nucleophilic reactivity of a representative series of anions has been measured in [hmim][ClO4] 3i, [hm2im][ClO4] 3′i, and [hmim][PF6] 3l ILs in the reaction with n-alkyl methanesulfonates and compared with that found in common molecular solvents (MeOH, DMSO, PhCl). The reactivity is found to depend on both the imidazolium cation-anion interaction and the specific solvation by water present in the IL, the water playing the main effect, in particular with hydrophilic anions. Removal of the largest quantity of water remarkably increases the ion pair reactivity in the IL up to rate constant value k comparable with those obtained in DMSO and in low polarity media (PhCl).
- Betti, Cecilia,Landini, Dario,Maia, Angelamaria
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p. 1689 - 1695
(2008/09/18)
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- The chemistry of cyclic carbaphosphazenes: The first observation of (R 2PN)(ClCN)2 (R=Cl, Ph) as a reagent for the conversion of alcohols to aldehydes, ketones, and alkyl chlorides
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The oxidation of nine primary and secondary alcohols to the corresponding aldehydes and ketones has been carried out under mild conditions and in good yields using the cyclocarbaphosphazenes (R2PN)(ClCN)2 [R2P = Cl2 P(1), Ph2P(2)] along with dimethylsulfoxide. While both the P-Cl and C-Cl bonds of the carbaphosphazene can in principle bring about the reaction, we observed an increased preference for the C-Cl bonds over the P-Cl bonds in the oxidation of alcohol. Blocking the reactive P site on the heterocyclic ring with the phenyl groups was found to reduce the yields of the oxidized products, while blocking the C- sites with diethylamino groups resulted in no reaction. In addition, along with DMF, the same cyclocarbaphosphazene has been found to be useful for the conversion of alcohols to alkyl chlorides. Copyright Taylor & Francis Group, LLC.
- Behera, Nabakrushna,Mishra, Pradyumna Kumar,Elias, Anil J.
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p. 2445 - 2452
(2007/10/03)
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- Process to convert alkanes into primary alcohols
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This invention provides a process to convert alkanes to primary alcohols of the same carbon number. Carbon numbers of particular interest are C8 to C18. The process comprises the steps of: a) halogenating a linear or branched (or mixture of linear and branched) alkane to produce a mixture of primary mono-haloalkanes, internal mono-haloalkanes, unreacted alkanes, hydrogen halide, and possibly multi-haloalkanes in the presence of a catalyst and/or by heating the reaction mixture; b) separating the hydrogen halide from the mixture and optionally neutralizing it with a metal oxide to produce a partially halogenated metal oxide and/or metal halide which may be regenerated; c) separating the primary mono-haloalkanes from the mixture; d) reacting the separated primary mono-haloalkanes in a reactor with a metal oxide or combination of metal oxides and water to convert the aforesaid primary mono-haloalkane to a mixture of products that contains primary alcohols, unconverted primary mono-haloalkanes, and possibly other reaction products, and a partially halogenated metal oxide and/or metal halide which may be regenerated; e) regenerating the partially halogenated metal oxide and/or metal halide to halogen (such as Cl2) and/or acid and a metal oxide for recycle by reaction with air or oxygen; and f) removing the unreacted primary mono-haloalkane from the reaction mixture and then purifying the primary alcohol.
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Page/Page column 4
(2008/06/13)
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- Process to convert linear alkanes into alpha olefins
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This invention provides for a process to convert branched or linear alkanes to branched or linear alpha olefins (AO) of the same carbon number. The process comprises the steps of: a) halogenating linear alkanes, branched alkanes, or a mixture of linear and branched alkane to produce a mixture containing primary mono-haloalkanes and hydrogen halide; b) separating the hydrogen halide from the mixture and optionally neutralizing it with a metal oxide to produce a partially halogenated metal oxide and/or metal halide which may be regenerated; c) separating the primary mono-haloalkanes from the mixture; d) reacting the separated primary mono-haloalkanes with a metal oxide to produce a mixture of products that contains alpha olefins, unconverted primary mono-haloalkanes, possibly other reaction products, and a partially halogenated metal oxide and/or metal halide which may be regenerated; e) regenerating the partially halogenated metal oxide and/or metal halide to halogen and/or acid and a metal oxide (such as Cl2) for recycle by reaction with air or oxygen ; and f) removing the unreacted primary mono-haloalkane from the reaction mixture and then purifying the alpha olefin.
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Page/Page column 4
(2008/06/13)
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- Anion nucleophilicity in ionic liquids: A comparison with traditional molecular solvents of different polarity
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The nucleophilic reactivity of a homogeneous series of anions (halides, pseudohalides and organic anions) in the ionic liquids [hexmim] [ClO 4] and [hexmim] [PF6] has been measured in their reaction with n-alkyl methanesulfonates, and compared with that found in traditional molecular solvents of different polarity, that is, chlorobenzene, DMSO, and MeOH.
- Landini, Dario,Maia, Angelamaria
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p. 3961 - 3963
(2007/10/03)
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- Catalytic process for regiospecific chlorination of alkanes, alkenes and arenes
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The present invention provides a process for regiospecific chlorination of an aromatic or aliphatic compound with a chlorine source comprising a metal chloride and other than Cl2and SO2Cl2in presence of hypervalent iodine catalyst and in acidic medium.
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Page column 7
(2008/06/13)
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- Generation of alkyl hypochlorites in oxidation of alcohols with carbon tetrachloride catalyzed by vanadium and manganese compounds
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Primary alcohols and diols with various structures were subjected to transformations into esters, aldehydes, ketones, and lactones under the action of carbon tetrachloride in the presence of manganese compounds (MnCl 2, MnO2, Mn(OAc)2, Mn(acac)3) and vanadium compounds (VCl5, V2O5, VO(acac) 2) as catalysts. These transformation proceeded with the involvement of alkyl hypochlorites, which were generated in the course of oxidation of alcohols with carbon tetrachloride catalyzed by manganese or vanadium compounds. The optimum molar ratios between the catalyst and reagents were determined, and the reaction conditions for the highly selective synthesis of esters, aldehydes, ketones, and lactones from alcohols were found.
- Khusnutdinov,Shchadneva,Baiguzina,Lavrentieva,Dzhemilev
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p. 2074 - 2079
(2007/10/03)
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- An efficient route to alkyl chlorides from alcohols using the complex TCT/DMF
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(formula presented) Efficient conversion of alcohols and β-amino alcohols to the corresponding chlorides (and bromides) can be carried out at room temperature in methylene chloride, using 2,4,6-trichloro[1,3,5]triazine and N,N-dimethyl formamide. This procedure can also be applied to optically active carbinols.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 553 - 555
(2007/10/03)
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- Conversion of alcohols into alkyl chlorides using trichloroisocyanuric acid with triphenylphosphine
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Trichloroisocyanuric acid with triphenylphosphine in anhydrous acetonitrile will convert alcohols into alkyl halides.
- Hiegel, Gene A.,Rubino, Mark
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p. 2691 - 2694
(2007/10/03)
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- New aspect of nucleophilic reactivity of tertiary phosphine oxides. R3PO-POCl3 binary system
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The reaction of tertiary phosphine oxides with phosphorus oxychloride was found to give triorganylphosphonium dichlorophosphates R3PCl+PO2Cl-2 rather than phosphorylphosphonium salts R3P · OPOCl2. Mixtures of the reagents, called binary system, possess a considerable synthetic potential. They are capable of converting alcohols to the corresponding alkyl chlorides.
- Kazantseva,Timokhin,Rokhin,Blazhev,Golubin,Rybakova
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p. 1233 - 1235
(2007/10/03)
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- Cross-coupling of organic compounds using cuprous iodide
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Cross-coupling or addition reactions of organic compounds, including acid halides, allylic halides, and α,β-unsaturated carbonyl containing compounds, with organozinc compounds may be readily and safely carried out in the presence of cuprous iodide. The use of this catalyst in the coupling reaction provides for the preparation of commercially useful products in the pharmaceutical, agrochemical and other industries.
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-
- Influence of Haloalkanes on the Selectivity of Radical Chlorination of Saturated Hydrocarbons
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The selectivity of radical chlorination of alkanes with molecular chlorine increases when the reaction is carried out in halogenated hydrocarbons. The relations of the observed selectivity to the concentrations of the solvent and the substrate suggest formation of a complex between chlorine atom and haloalkane molecule.
- Dneprovskii,Eliseenkov,Kuznetsov
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p. 637 - 641
(2007/10/03)
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- Preparative catalytic chlorination of adamantane, cyclohexane, and hexane in the system tetrachloromethane-MX2(PPh3)2 (MX2 = PdBr2, PtCl2)-acetonitrile-potassium carbonate
-
Heating of saturated hydrocarbons RH (cyclohexane, adamantane, and hexane) with tetrachloromethane in the presence of acetonitrile, potassium carbonate, and catalytic amounts of dihalide triphenylphosphine complexes of palladium(II) or platinum(II), MX2(PPh)2 (MX2 = PdBr2, PtCi2), for 6-8 h at 120°C yields monochlorinated derivatives of the respective hydrocarbons in 30-55% yield. Benzene, toluene, ethylbenzene, and tetramethylsilane show low reactivity under the conditions adopted for the reaction. Relative reactivity of various bond types C-H of alkanes is in agreement with the well known sequence: tertiary > secondary > primary. A scheme is proposed assuming trichloromethyl radicals as active species, and the catalyst function consists in activating C-C1 bond of the tetrachloromethane.
- Vedernikov,Sayakhov,Zazybin,Solomonov
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p. 812 - 815
(2007/10/03)
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- New Catalytic System for Activation of Alkane and Arene C-H Bonds on the Basis of Platinum(II) Complexes and Tetrachloromethane
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Alkanes and alkylarencs RH (cyclohexane, n-hexane, toluene) in a mixture with CCl4 and MeCN (1:1:1, by volume), at temperatures of 110°C and higher, in the presence of platinum complexes of the formula cis-PtX2(L)2 (X = Cl, Ph, L = PPh3; X = Cl, L = MeCN), react to form chloroform and chloride RCl. Catalytic activity decreases in the order PtPh2(PPh3)2 (3.9) > PtCl2(PPh3)2 (1.0) > PtCl2(MeCN)2 (0.24). In the case of n-hexane, C-H bonds at the secondary carbon atoms are by a factor of 11 more active than those at the primary atom, and in the case of toluene, benzyl chloride is the main reaction product (99%). The reaction is first-order in cyclohexane, metal complex, and tetrachloromethane. The chlorination of toluene is zero-order in hydrocarbon. The results of kinetic studies permit to conclude that the role of the catalyst is to activate the tetrachloromethane C-Cl bonds by an oxidative addition scheme.
- Vedernikov,Zazybin,Borisoglebskii,Solomonov
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p. 1922 - 1924
(2007/10/03)
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- Electrochemical Reduction of 1,6-Dihalohexanes at Carbon Cathodes in Dimethylformamide
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Cyclic voltammograms for the reduction of 1,6-dibromo-, 1,6-diiodo-, 1-bromo-6-chloro-, and 1-chloro-6-iodohexane at glassy carbon electrodes in dimethylformamide containing tetramethylammonium perchlorate exhibit single irreversible waves that correspond to the reductive cleavage of carbon-bromine or carbon-iodine bonds.When large-scale controlled-potential electrolyses of either 1,6-dibromo- or 1,6-diiodohexane are performed at reticulated vitreous carbon, the principal products are n-hexane (30-45percent), 1-hexene (28-34percent), 1,5-hexadiene (6-16percent), and cyclohexane (7percent), with n-dodecane being another significant species obtained from 1,6-diiodohexane.Because a carbon-chlorine bond is not directly reducible, 1-bromo-6-chloro- and 1-chloro-5-iodohexane give rise mainly to 1-chlorohexane (47-64percent), 6-chloro-1-hexene (20-33percent), and 1,12-dichlorododecane (2-25percent).From these product distributions, and with the aid of experiments done in the presence of deuterium-labeled reagents, we conclude that the electrolytic reduction of 1,6-diiodo- and 1-chloro-6-iodohexane involves both radical and carbanion intermediates, whereas only carbanionic pathways are important for electrolyses of 1,6-dibromo- and 1-bromo-6-chlorohexane.
- Mubarak, Mohammad S.,Peters, Dennis G.
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p. 681 - 685
(2007/10/02)
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- Intramolecular H-Transfer Reactions During the Decomposition of Alkylhydroperoxides in Hydrocarbons as the Solvents
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Eight defined primary and secondary alkylhydroperoxides were decomposed in n-alkanes as the solvent, mostly in the presence of manganese stearate.In all cases the corresponding alcohols and carbonyl compounds were formed as the main products with yields of 60-90percent.Besides, difunctional products were formed by an intramolecular H-transfer in the alkoxy radicals corresponding to the starting hydroperoxides.Products possibly formed by an intramolecular H-transfer in the corresponding alkylperoxy radical could be found only in the case of 4-methyl-2-hydroperoxy pentane.The amount of products formed by intramolecular H-transfer depended on the nature of the C-H bond in δ-position to the original hydroperoxy group and lay between 4percent (primary C-H in the case of 4-hydroperoxy heptane) and 13percent (tertiary C-H in the case of 2-hydroperoxy-5-methyl hexane) with respect to the starting hydroperoxide.The amount of products formed by oxidative attack of the alkoxy and alkylperoxy radicals at the normal paraffins used as the solvents was unexpectedly low (always less than 10percent with respect to the starting hydroperoxide).An increment system is proposed for the calculation of 13C-nmr shifts in alkyl hydroperoxides.
- Jinsheng, Li,Pritzkow, Wilhelm,Voerckel, Volkmar
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- Cobalt(II)-Porphyrin Catalyzed Selective Functionalization of Alkanes with sulfurylchloride: A Remarkable Substituent Effect
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Cobalt(II)-porphyrin complex 1 and 2 catalyses the chlorination and sulfochlorination respectively of n-alkanes and cycloalkanes with sulfuryl chloride in benzene.The p-substituent of the benzene ring in the porphyrin complex 1 and 2 shows a remarkable chemoselectivity in these reactions.
- Khanna, Vibha,Tamilselvan, Pitchiah,Kalra, Swinder Jeet Singh,Iqbal, Javed
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p. 5935 - 5938
(2007/10/02)
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- CHIRAL COMPLEX-FORMING AGENTS AND TRANS-PHASE TRANSFER AGENTS. 5. 3S-HYDROXY-1-ALKYLQUINUCLIDINIUM SALTS AND THEIR PROPERTIES.
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Synthesized 3-hydroxy- and 3-benzyloxy-1-benzylquinuclidinium salts are in their catalytic activity comparable to benzyl(triethyl)ammonium chloride and are inferior to catalysts of the tetraalkylammonium type.The asymmetry-induced capability of chiral 3-hydroxy-1-alkylquinuclidinium salts is considerably inferior to the asymmetry-induced capability of the conformationally mobile N-benzylquininium chloride, which indicates the dependence of the asymmetric induction on the possibility of the approach of the β-hydroxylic group and the ammonium center of the catalyst in the transition state of the reaction.
- Esikova, I. A.,Serebryakov, E. P.
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p. 1682 - 1690
(2007/10/02)
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- Reactions of Alkylmercurials with Heteroatom-Centered Acceptor Radicals
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The relative reactivities of alkylmercury halides toward PhS., PhSe., or I. decrease drastically from R = tert-butyl to R = sec-alkyl to R = n-butyl, indicative that R. is formed in the rate-determining step in the attack of these radicals upon RHgCl.The alkyl radicals thus formed will enter into chain reactions in which a heteroatom-centered radical (A.) is regenerated from substrates such as RS-SR, ArSe-SeAr, ArTe-TeAr, PhSe-SO2Ar, Cl-SO2Ph; ZCH=CHA (A = Cl, I, SPh, SO2Ph); or PhCCHA (A = I, SPh, SO2Ph). β-Styrenyl (PhCH=CHA, Ph2C=CHA) and β-phenethynyl (PhCCA) systems with A = I, Br, SO2Ph also enter into chain reactions with mercury(II) salts with the ligands PhS, PhSe, PhSO2, or (EtO)2PO.The relative reactivities of a series of reagents toward t-Bu. and of PhCH=CHA, Ph2C=CHA, and PhCCA toward c-C6H11. are reported as well as the regioselectivity of t-Bu. attack observed for 1,2-disubstituted ethylenes (ZCH=CHA) with Z and A from the group Ph, Cl, Br, I, SO2Ph, SPh, Bu3Sn.Reactions of (E)- and (Z)-PhCH=CHI or MeO2CCH=CHI with t-Bu. or c-C6H11. occurred in a regioselective and stereospecific (retention) manner.Reactions of (E)- and (Z)-ClCH=CHCl occurred in a nonstereospecific manner in which the E/Z product ratio increased with the bulk of the attacking radical.A similar effect on the E/Z product ratios was observed for (Z)-MeO2CCH=CHCl.
- Russell, Glen A.,Ngoviwatchai, Preecha,Tashtoush, Hasan I.,Pla-Dalmau, Anna,Khanna, Rajive K.
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p. 3530 - 3538
(2007/10/02)
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- Organic Synthesis in Micellar Media. Oxidation of Alcohols and Their Conversion into Alkyl Chlorides
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The use of micelles was investigated for various organic reactions: oxidation of alcohols with sodium hypochlorite in micelles, oxidation of alcohols with hexadecyltrimethylammonium chromate as micelle, and conversion of primary alcohols to 1-chloroalkanes by aqueous hydrogen chloride in the presence of micelles.In all cases, product isolation was simple and satisfactory yields were obtained.
- Jursic, Branko
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p. 868 - 871
(2007/10/02)
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- HOMOLOGATION DES DERIVES HALOGENES
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The halide R-X is converted, in two steps, to its homologous R-CH2-X.
- Yankep, Emmanuel,Charles, Georges
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p. 427 - 430
(2007/10/02)
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- FREE RADICAL HALOGENATION OF ALKANES INITIATED BY TRANSITION METAL COMPLEXES
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Reaction between halocarbons (particularly CCl4) and hydrocarbons (particularly c-C6H12) in the presence of a range of low valent metal complexes have been investigated.A delaited study of the reaction involving has shown it to proceed by a free radical chain route in which the metal complex acts solely as an initiator.Similar behaviour has been confirmed for . (Re2(CO)10> and show initiation efficiencies comparable with organic peroxides, but other complexes are less efficient.Factors effecting efficiencies have been studied.
- Davis, Reg,Durrant, Jim L. A.,Rowland, Christopher C.
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p. 147 - 162
(2007/10/02)
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- New Reagents, XXXII, Alkyldiphenylbismutanes: Synthesis, Properties, and Halogenolysis
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Alkyldiphenylbismutanes 1 have been synthesized for the first time (61-92 percent).These compounds are air sensitive, not spontaneously inflammable liquids which decompose not below ca. 170 deg C.The diphenylbismutino group is very good equivalent for Cl- or Br-substituents at aliphatic residues since halogenolysis of the Bi-Alk bond with SO2Cl2 or Br2 already occurs at -40 to 0 deg C (corresponding fissions of As-Alk and Sb-Alk bonds afford heating to ca. 130 or ca. 220 deg C).
- Kauffmann, Thomas,Steinseifer, Fritz
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p. 1031 - 1038
(2007/10/02)
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- Oxidatively Assisted Nucleophic Substitution of Iodine in Alkyl Iodides by Nucleofugic Anions
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The reaction of alkyl iodides with chlorine or nitronium tetrafluoroborate in the presence of salts of perchloric or substitued sulfonic acids gave alkyl perchlorates or sulfonates as principal products.Some mechanistic aspects of this new reaction are discussed.
- Zefirow, Nikolai S.,Zhdankin, Victor V.,Makhon'kova, Galina V.,Dan'kov, Yuri V.,Koz'min, Anatoly S.
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p. 1872 - 1876
(2007/10/02)
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- FREE-RADICAL CHLORINATION OF ACETALS AND ORTHO ESTERS
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The chlorination of 1,3-dioxolane and ortho esters (trihexyloxymethane and 2-hexyloxy-1,3-dioxolane) in the presence of azobisisobutyronitrile was studied. 2-Chloroethyl formate is formed in the case of dioxolane and 2-chloroethyl formate, ethylene carbonate, and hexyl chloride are formed in the case of 2-hexyloxy-1,3-dioxolane.
- Rol'nik, L. Z.,Pastushenko, E. V.,Zlot-skii, S. S.,Rakhmankulov, D. L.
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p. 1498 - 1500
(2007/10/02)
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