- Highly efficient two-step selective synthesis of 2,6-dimethylnaphthalene
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2,6-Dimethylnaphthalene (2,6-DMN), a key raw material for poly(ethylene naphthalate) (PEN), was selectively synthesized via a two-step process in an overall 66% yield from commercially available 4-bromotoluene and 3-methyl-3-buten-1-ol. The ligand-free Heck reaction of the starting materials produced γ-(p-tolyl)-substituted aldehyde that was cyclized with an acid to give 2,6-DMN after in situ oxidation. No other isomers of 2,6-DMN were found.
- Kim, Byung Hyun,Lee, Jong Gil,Yim, Taeeun,Kim, Hyo-Jin,Lee, Hyun Yeong,Kim, Young Gyu
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Read Online
- RETRACTED ARTICLE: Study on Methylation of Naphthalene with Methanol over ZSM-5 (core)/SAPO-11(shell) Composite Molecular Sieve
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Abstract: ZSM-5 (core)/SAPO-11 (shell) composite molecular sieve was synthesized by the hydrothermal method in order to combine the advantages of ZSM-5 and SAPO-11 materials for the methylation of naphthalene with methanol. For comparison, the catalytic performance of mechanical mixture of ZSM-5 and SAPO-11 was also evaluated. The characterization results proved that ZSM-5/SAPO-11 composite has a core-shell structure. The pore size of the composite was between that of ZSM-5 and SAPO-11. The composite had fewer acid sites than ZSM-5 and mechanical mixture, but more acid sites than SAPO-11. The experimental results indicated that the composite exhibited good catalytic performance in the methylation of naphthalene with methanol.
- Xiaoxiao Wang,Guo, Fang,Wei, Xianxian,Liu, Zhenmin,Wang, Yingchun,Guo, Shaoqing,Wang, Yuanyang,Yu, Yue
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Read Online
- Controllable synthesis of chainlike hierarchical ZSM-5 templated by sucrose and its catalytic performance
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Hierarchical ZSM-5 with controllable chainlike structure was hydrothermally synthesized with sucrose as template, characterized by XRD, FT-IR, N2 adsorption, SEM and TEM, and used for methylation of 2-methylnaphthalene. Hierarchical ZSM-5 can be rapidly synthesized, and chainlike morphology is stacked with several submicron crystals. With increasing sucrose amount in the precursor, the chain structure became more obvious, and the surface area and pore volume of mesopores increased. Narrow mesoporous distribution was centered at about 7 nm. It is thought that the formation of mesopores is related to the template role of sucrose. Chainlike hierarchical ZSM-5 exhibited high 2-methylnaphthalene conversion and 2,6-dimethylnaphthalene yield.
- Jin, Lijun,Xie, Tong,Liu, Sibao,Li, Yexin,Hu, Haoquan
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Read Online
- Preparation method of 2, 6-dimethylnaphthalene
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The invention discloses a preparation method of 2, 6-dimethylnaphthalene, which is characterized in that 3, 4-dichlorotoluene and isoprene are used as raw materials and react in the presence of a Pd catalyst to prepare the 2, 6-dimethylnaphthalene. According to the method, 3, 4-dichlorotoluene and isoprene are taken as raw materials, and 2, 6-dimethylnaphthalene (2, 6-DMN) is efficiently synthesized by a one-step method through C-C coupling reaction under relatively mild conditions, so that the defects of long process route, harsh reaction conditions and low yield of 2, 6-DMN in the prior art are overcome.
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Paragraph 0038; 0042-0061
(2021/09/21)
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- Synthesis of renewable alkylated naphthalenes with benzaldehyde and angelica lactone
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Herein, we report a new route for the synthesis of renewable alkylated naphthalenes (ANs) with benzaldehyde and angelica lactone, two platform compounds that can be derived from lignocellulose.
- Cong, Yu,Li, Guangyi,Li, Ning,Wang, Aiqin,Wang, Ran,Wang, Xiaodong,Xu, Jilei,Zhang, Tao
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supporting information
p. 5474 - 5480
(2021/08/16)
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- Synthesis of Nanosized ZSM-5 Zeolites by Different Methods and Their Catalytic Performance in the Alkylation of Naphthalene
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Abstract: Three nanosized ZSM-5 zeolites were successfully prepared from reactive gelswith the same Si/Al ratios by different synthetic procedures that included theuse of tetrapropylammonium hydroxide or n-butylamine as a template and a seedingmethod that did not use an organic additive. The effect of the synthetic methodon the physicochemical properties of the prepared samples was investigated byXRD, XRF, XPS, N2 physisorption, SEM, TEM,27Al MAS NMR, NH3-TPD, andPy-FTIR. The catalytic performance of thenanosized ZSM-5 zeolites in the alkylation of naphthalene with methanol wascompared. The prepared samples were phase-pure, highly crystalline ZSM-5zeolites, but they had different bulk and surface Si/Al ratios as well astextural and acidic properties. The study of the prepared catalysts innaphthalene methylation revealed that both the acid characteristics of the ZSM-5nanosized zeolites and their textural properties were responsible for theiractivity in the reaction. A difference in the composition ofmonomethylnaphthalenes and dimethylnaphthalenes was attributed to the ability ofthe catalyst to isomerize the primary reaction products on acid sites located onthe external surface of the zeolite crystals. 2,7-DMN was found to be thepreferred reaction product over 2,6-DMN when formed at pore entrances to ZSM-5channels due to the differences in their dimensions. In contrast,2,6-dimethylnaphthalene could be produced on weaker external Br?nsted acidsites, which are hydroxyls attached to octahedral Al atoms. The presentedresults show that the method used to synthesize nanoscale ZSM-5 zeolites is acritical factor that determines the physicochemical properties and catalyticperformance of the resulting crystals.
- Wang, Yongchao,Kikhtyanin,Li, Cheng,Su, Xiaofang,Bai, Xuefeng,Wu, Wei
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p. 394 - 406
(2021/02/26)
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- Method for preparing 2, 6-dimethylnaphthalene
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The invention relates to a method for preparing a bicyclic aromatic chemical 2, 6-dimethylnaphthalene (2, 6-DMN) from isoprene and 3-cyclohexene formaldehyde. The method comprises the following steps:heating the isoprene and the 3-cyclohexene formaldehyde or heating the isoprene and the 3-cyclohexene formaldehyde under a Lewis acid heating condition to carry out Diels-Alder reaction at the temperature of 200-350 DEG C to generate an organic matter A with the structure shown in the specification, and carrying out dehydrogenation and hydrodeoxygenation reaction on the organic matter A at the temperature of 300-450 DEG C at the same time to generate the 2, 6-dimethylnaphthalene. The process is simple in reaction procedure and high in target product selectivity, and a new route for preparingthe bicyclic aromatic compound from biomass resources is provided.
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Paragraph 0008; 0025-0029
(2020/06/20)
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- Method for preparing 2,6-dimethylnaphthalene from isoprene and methyl p-benzoquinone
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The invention relates to a method for preparing 2,6-dimethylnaphthalene from isoprene and methyl p-benzoquinone. The process comprises two steps: 1, carrying out a Diels-Alder reaction on isoprene andmethyl p-benzoquinone under the action of a Lewis acid catalyst or pure thermal synthesis at 20-80 DEG C to generate a dimethyl hexahydronaphthalene dione intermediate product; and 2, carrying out dehydrogenation and deoxidation under the action of a Cu-based catalyst to generate 2,6-dimethylnaphthalene, wherein the synthesis of the intermediate product can be realized by taking isoprene and methyl p-benzoquinone from biomass resources as raw materials through common heating or microwave heating in a tank reactor, dehydrogenation and deoxidation reactions can be carried out in a fixed bed reactor, and the reaction intermediate is directly injected into a reaction tube or passes through a catalyst bed layer under purging of carrier gas to obtain 2,6-dimethylnaphthalene. The process is simple in reaction procedure and high in target product selectivity, and a new route for preparing dimethylnaphthalene from biomass resources is provided.
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Paragraph 0043-0052
(2020/06/17)
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- Methylation of 2-methylnaphthalene over metal-impregnated mesoporous MCM-41 for the synthesis of 2,6-triad dimethylnaphthalene isomers
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2,6-Dimethylnaphthalene (2,6-DMN) is one of the key intermediates for the production of polyethylene naphthalate (PEN), which demonstrates superior properties compared with the polyethylene terephthalate. However, the complex synthesis procedure of 2,6-DMN increases the production cost and decreases the commercialisation of PEN. In this study, selective synthesis of 2,6-triad DMN isomers (1,5-DMN, 1,6-DMN and 2,6-DMN) has been investigated by the methylation of 2-methylnaphthalene (2-MN) over mesoporous Cu/MCM-41 and Zr/MCM-41 zeolite catalysts. On the contrary of other DMN isomers, 2.6-triad isomers can effectively be converted to be profitable 2,6-DMN with an additional isomerisation reaction, which is a new approach to reach higher 2,6-DMN yield. The methylation reactions of 2-MN were investigated in a fixed-bed reactor at 400?°C and weight hourly space velocity of 1–3?h?1. The results showed that the activity of MCM-41 on the methylation of 2-MN has been enhanced with the impregnation of Cu. The conversion increased from about 17% to 35 wt% with the impregnation of Cu. Similarly, the 2,6-triad DMN selectivity and 2,6-/2,7-DMN ratio reached the maximum level (48 wt% and 1.95, respectively) over Cu-impregnated MCM-41 zeolite catalyst.
- Niftaliyeva, Aysel,Güle?, Fatih,Karaduman, Ali
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p. 2403 - 2416
(2020/02/11)
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- A compound two spiral alkylations, ZSM - 12 molecular sieve preparation method and the preparation of ZSM - 12 molecular sieve and alkylation method
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The invention discloses a di-spirane compound, a preparation method for a ZSM-12 molecular sieve, the prepared ZSM-12 molecular sieve and an alkylation method. The di-spirane compound has a structureshown in a formula (I), wherein n is 2-6, X is an anion selected from Cl, Br, I or OH. The ZSM-12 molecular sieve is prepared by using the di-spirane compound provided by the invention; when the prepared ZSM-12 molecular sieve is used for catalyzing the alkylation method, the conversion rate is high, and the selectivity is good.
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Paragraph 0090-0094; 0098
(2019/10/04)
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- Selective synthesis of 2,6-triad dimethylnaphthalene isomers by disproportionation of 2-methylnaphthalene over mesoporous MCM-41
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2,6-Dimethylnaphthalene (2,6-DMN) is one of the crucial intermediates for the synthesis of polybutylenenaphthalate and polyethylene naphthalate (PEN). The complex synthesis procedure and the high cost of 2,6-DMN production significantly reduce the commercialisation of PEN even though PEN demonstrates superior properties compared with polyethylene terephthalate. 2,6-DMN can be produced by methylation of 2-methylnaphthalene (2-MN) and/or naphthalene, disproportionation of 2-MN, and/or isomerisation of dimethylnaphthalenes (DMNs). In this study, synthesis of 2,6-triad DMN isomers consisting of 2,6-DMN, 1,6-DMN, and 1,5-DMN have been investigated with the disproportionation of 2-MN over unmodified and Zr-modified mesoporous MCM-41 zeolite catalysts. In contrast to other DMN isomers, both 1,5-DMN and 1,6-DMN can be effectively isomerised to be profitable 2,6-DMN. The disproportionation of 2-MN experiments were carried out in a catalytic fixed-bed reactor in the presence of 1?g of catalyst at a temperature range of 350–500?°C and weight hourly space velocity between 1 to 3?h?1. The results demonstrated that mesoporous MCM-41 zeolite catalyst has a selective pore shape for 2,6-triad DMN isomers, which may allow a decrease in the production cost of 2,6-DMN. Additionally, 2,6-DMN was successfully synthesised by the disproportionation of 2-MN over MCM-41 zeolite catalyst. Furthermore, both the conversion of 2-MN and the selectivity of 2,6-DMN were considerably enhanced by the Zr impregnation on MCM-41.
- Güle?, Fatih,Niftaliyeva, Aysel,Karaduman, Ali
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p. 7205 - 7218
(2018/08/22)
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- Decarbonylative Methylation of Aromatic Esters by a Nickel Catalyst
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A Ni-catalyzed decarbonylative methylation of aromatic esters was achieved using methylaluminums as methylating agents. Dimethylaluminum chlorides uniquely worked as the methyl source. Because of the Lewis acidity of aluminum reagents, less reactive alkyl esters could also undergo the present methylation. By controlling the Lewis acidity of aluminum reagents, a chemoselective decarbonylative cross-coupling between alkyl esters and phenyl esters was successful.
- Okita, Toshimasa,Muto, Kei,Yamaguchi, Junichiro
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p. 3132 - 3135
(2018/05/28)
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- Methylation of Arenols through Ni-catalyzed C—O Activation with Methyl Magnesium Bromide
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Direct alkylation of arenols with alkyl organometallic reagents has never been approached. Herein we reported the first successful example of nickel-catalyzed methylation of arenols with methyl Grignard reagents to construct C(sp2)-C(sp3/
- Shi, Wen-Juan,Shi, Zhang-Jie
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supporting information
p. 183 - 186
(2018/01/15)
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- Shape-selective methylation of naphthalene with methanol over SAPO-11 molecular sieve modified with hydrochloric acid and citric acid
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Herein, a series of SAPO-11 molecular sieves were modified by citric acid and hydrochloric acid. They were characterized by ICP, XRD, SEM, N2 adsorption-desorption, NH3-TPD, 29Si MAS NMR, and Py-IR and evaluated by the methylation of naphthalene with methanol to 2,6-dimethylnaphthalene (2,6-DMN). According to the XRD results, hydrochloric acid at a high concentration not only removed extra-framework aluminum but also deleted framework silicon; this resulted in the formation of crystal defects. N2 adsorption-desorption results showed that all the samples possessed micropores and secondary mesopores. The SAPO-11 sample modified with 4 mol L-1 hydrochloric acid for 30 min exhibited the largest secondary mesopore size distributions. NH3-TPD and 29Si MAS NMR showed that hydrochloric acid at a high concentration could eliminate more acid sites. SAPO-11 modified with 4 mol L-1 hydrochloric acid for 30 min presented high catalytic performance for the methylation of naphthalene; this was mainly attributed to the amount of secondary mesopores in the SAPO-11 molecular sieves.
- Wang, Xiaoxiao,Liu, Zhenmin,Guo, Fang,Wang, Yingchun,Wei, Xianxian,Li, Peng,Xue, Yongbing,Wang, Yuanyang,Guo, Shaoqing,Yu, Yue
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p. 243 - 250
(2018/01/17)
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- A 2, 6 - dimethylnaphthalene as pesticides in the auxiliary agent application and its preparation method (by machine translation)
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The invention also provides a 2, 6 - dimethylnaphthalene in insecticide preparation application, 2, 6 - dimethylnaphthalene can be as a high activity, environment-friendly additive added to the pesticide, effectively reduce the surface tension of the solution, make the insecticide of a layer of the protective film is formed on the surface, the surface of the enhancing agent in the smell and pests, and adhesion of the cloth, so as to improve the potency. Experimental results show that, added 2, 6 - dimethylnaphthalene insecticide activity improved by 10%, the surface tension reducing 8 dynes/cm. The invention will be 2, 6 - dimethylnaphthalene added to in the extinguishes sweeps the advantage, carrying out field test, the result shows that, added 2, 6 - dimethylnaphthalene extinguishes sweepsadvantage medication 3 days, 6 days and 9 days respectively insect decrease rate 92.92%, 93 . 80% and 94.69%. The invention also provides a 2, 6 - dimethylnaphthalene preparation method. (by machine translation)
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Paragraph 0043-0054
(2017/02/28)
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- Nickel-Catalyzed Borylation of Aryl and Benzyl 2-Pyridyl Ethers: A Method for Converting a Robust ortho-Directing Group
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The nickel-catalyzed borylation of aryl 2-pyridyl ethers via the loss of a 2-pyridyloxy group is described. This method allows a 2-pyridyloxy group to be used as a convertible directing group in C?H bond functionalization reactions. The nickel catalyst can also borylate arylmethyl 2-pyridyl ethers, in which the stereochemistry at the benzylic position is retained in the case of chiral secondary benzylic substrates. (Figure presented.).
- Tobisu, Mamoru,Zhao, Jiangning,Kinuta, Hirotaka,Furukawa, Takayuki,Igarashi, Takuya,Chatani, Naoto
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supporting information
p. 2417 - 2421
(2016/08/16)
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- Kinetic and equilibrium parameters of [4+2] cycloaddition reaction of 2,6-dimethylnaphthalene with 4-phenyl-1,2,4-triazoline-3,5-dione
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Kinetic parameters of forward and retro Diels-Alder reactions between 2,6-dimethylnaphthalene and 4-phenyl-1,2,4-triazolinedione were determined, as well as the equilibrium parameters of the reaction in 1,2-dichloroethane.
- Kiselev,Kashaeva,Potapova,Kornilov,Konovalov
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p. 770 - 771
(2015/01/30)
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- Synthesis of hss (core)/sapo-11 (shell) composite molecular sieve and its catalytic performances in the methylation of naphthalene with methanol
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Hss (core)/SAPO-11 (shell) composite molecular sieve was synthesized by the hydrothermal method in order to combine the advantages of Hss and SAPO-11 for the methylation of naphthalene with methanol. For comparison, the mechanical mixture was prepared through the blending of Hss and SAPO-11. The physicochemical properties of Hss, SAPO-11, the composite and the mechanical mixture were characterized by various characterization methods. The characterization results indicated that Hss/SAPO-11 composite molecular sieve exhibited a core-shell structure, with the Hss phase as the core and the SAPO-11 phase as the shell. The pore diameter of the composite was between that of Hss and SAPO-11. The composite had fewer acid sites than Hss and mechanical mixture while more acid sites than SAPO-11. The experimental results indicated that the composite exhibited high catalytic performances for the methylation of naphthalene with methanol.
- Wang, Xiaoxiao,Guo, Shaoqing,Zhao, Liangfu
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p. 3829 - 3834
(2014/01/17)
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- Methylation of naphthalene on MTW-type zeolites. Influence of template origin and substitution of Al by Ga
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Two templates, methyltriethylammonium bromide (MTEA) and tetraethylammonium bromide (TEA) were used to synthesize aluminosilicate ZSM-12 zeolites. Additionally, zeolites isomorphously substituted (partially or totally) by gallium were prepared with MTEA.
- Wu, Wei,Wu, Weiguo,Kikhtyanin,Li, Lingfei,Toktarev,Ayupov,Khabibulin,Echevsky,Huang, Juan
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experimental part
p. 279 - 288
(2010/11/18)
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- Structure elucidation and enantioselective total synthesis of the HMG-CoA reductase inhibitors FR901512 and FR901516
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The enantioselective total synthesis of the potent HMGCoA reductase inhibitors FR901512 (1) and FR901516 (2) is reviewed. FR901512 was prepared in 15 steps from commercially available compound via 2 in 16.3% overall yield (89% average yield). This study validated the applicability and reliability of the catalytic asymmetric Nozaki-Hiyama reactions that were developed by us. These reactions enabled the concise, efficient, and protecting-group-free enantioselective total syntheses of these new statins.
- Inoue, Masahiro,Nakada, Masahisa
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scheme or table
p. 3694 - 3707
(2010/03/30)
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- Molecular tuning of phenylene-vinylene derivatives for two-photon photosensitized singlet oxygen production
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(Chemical Equation Presented) Substituent-dependent features and properties of the sensitizer play an important role in the photosensitized production of singlet oxygen, O2(a1Δg). In this work, we systematically examine the effect of molecular changes in the sensitizer on the efficiency of singlet oxygen production using, as the sensitizer, oligophenylene-vinylene derivatives designed to optimally absorb light in a nonlinear two-photon process. We demonstrate that one cannot always rely on rule-of-thumb guidelines when attempting to construct efficient two-photon singlet oxygen sensitizers. Rather, as a consequence of behavior that can deviate from the norm, a full investigation of the photophysical properties of the system is generally required. For example, it is acknowledged that the introduction of a ketone moiety to the sensitizer chromophore often results in more efficient production of singlet oxygen. However, we show here that the introduction of a carbonyl into a given phenylene-vinylene can, rather, have adverse effects on the yield of singlet oxygen produced. Using these molecules, we show that care must also be exercised when using qualitative symmetry-derived arguments to predict the relationship between one-and two-photon absorption spectra.
- Nielsen, Christian B.,Arnbjerg, Jacob,Johnsen, Mette,Joorgensen, Mikkel,Ogilby, Peter R.
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scheme or table
p. 9094 - 9104
(2010/03/04)
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- METHOD FOR ACHIEVING HIGH PURITY SEPARATION AND REFINEMENT BY CONTROLLING MORPHOLOGY AND PARTICLE SIZE OF 2,6-DIMETHYLNAPHTHALENE CRYSTALS
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The present invention relates to a method for achieving high purity separation and refinement by controlling morphology and particle size of 2,6-dimethylnaphthalene. And more particularly, the present invention relates to a method for obtaining high purity 2,6-dimethylnaphthalene crystals, in which crystallization is carried out with a solvent that enables the crystals to form a square-plate shape. During the process, crystallization variables such as, agitation speed, cooling rate, solvent and composition ratio, are adjusted to control morphology and particle size of 2,6-dimethylnaphthalene and to remove aggregation, thereby obtaining 2,6-dimethylnaphthalene crystals of high purity.
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Page/Page column 11
(2009/05/30)
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- Methylation of arenes via Ni-catalyzed aryl C-O/F activation
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Aryl C-O and C-F can be transformed into C-Me via Ni-catalyzed coupling with MeMgBr under mild conditions. The Royal Society of Chemistry.
- Guan, Bing-Tao,Xiang, Shi-Kai,Wu, Tao,Sun, Zuo-Peng,Wang, Bi-Qin,Zhao, Ke-Qing,Shi, Zhang-Jie
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p. 1437 - 1439
(2008/12/21)
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- METHOD AND SYSTEM FOR SEPARATION AND PURIFICATION OF HIGH-PURITY 2,6-DIMETHYLNAPHTHALENE BY CONTINUOUS CRYSTALLIZATION
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Provided is a method for the separation and purification of high-purity 2,6-dimethylnaphthalene from a reaction mixture of dimethylnaphthalenes by continuous crystallization. According to the method, shell-tubetype crystallization apparatuses are used to perform crystallization operations under a continuous flow of a reaction mixture of dimethylnaphthalenes, which is obtained from the synthesis of dimethylnaphthalenes using o-xylene and butadiene as starting materials. As a result, high-purity 2,6-dimethylnaphthalene is separated and purified in a high yield from the reaction mixture. In addition, the method is advantageous in terms of energy saving when compared to conventional separation methods and enables continuous separation and purification of 2,6-dimethylnaphthalene on an industrial scale. A system for implementing the method is further provided.
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Page/Page column 10-12
(2008/12/07)
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- Method for producing dimethylnaphthalene using a metal catalyst
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Disclosed herein is a process of producing high purity and high yield dimethylnaphthalene by dehydrogenating a dimethyltetralin isomer using a metal catalyst for dehydrogenation. The metal catalyst contains a carrier selected from alumina (Al2O3), silica (SiO2), a silica-alumina mixture and zeolite. The metal catalyst also contains 0.05 to 2.5 % by weight of platinum (Pt), 0.1 to 3.0 % by weight of tin (Sn) or indium (In), 0.5 to 15.0 % by weight of at least one selected from the group consisting of potassium (K), magnesium (Mg) and cesium (Cs), 0.3 to 3.0 % by weight of chlorine, and 0.01 to 3.0 % by weight of zinc (Zn) or gallium (Ga) as active components based on an element weight of the final catalyst.
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Page/Page column 7
(2008/06/13)
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- Dehydrogenation process of dimethylnaphthalene using metal catalyst
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Disclosed herein is a process of producing high purity and high yield dimethylnaphthalene by dehydrogenating a dimethyltetralin isomer using a metal catalyst for dehydrogenation. The metal catalyst contains a carrier selected from alumina (Al2O3), silica (SiO2), a silica-alumina mixture and zeolite. The metal catalyst also contains 0.05 to 2.5% by weight of platinum (Pt), 0.1 to 3.0% by weight of tin (Sn) or indium (In), 0.5 to 15.0% by weight of at least one selected from the group consisting of potassium (K), magnesium (Mg) and cesium (Cs), 0.3 to 3.0% by weight of chlorine, and 0.01 to 3.0 % by weight of zinc (Zn) or gallium (Ga) as active components based on an element weight of the final catalyst.
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Page/Page column 5-6
(2008/06/13)
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- Method for obtaining 2,6-dimethylnaphthalene using isomerization and crystallization processes
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The present invention relates to a method for preparation, separation and purification of high-purity 2,6-dimethylnaphthalene. The method according to the present invention comprises a step of subjecting a dimethylnaphthalene isomer mixture rich in 1,5-dimethylnaphthalene, high boiling point materials, unreacted 1,5-dimethyltetralin, and low boiling point materials, which are produced from a dehydrogenation reaction of 1,5-dimethyltetralin, to separation, using a distillation column;a step of subjecting the dimethylnaphthalene mixture separated by the distillation column to liquid state isomerization in the presence of an isomerization catalyst;a first crystallization step (melt crystallization process) of cooling the product of liquid state isomerization with a refrigerant without a solvent to form crystals; anda second crystallization step (solution crystallization process) of mixing the product of the first crystallization step with a solvent to form crystals.
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Page/Page column 11; 14
(2008/06/13)
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- Method for separating and purifying 2,6-dimethylnaphthalene
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A method for separating and purifying 2,6-dimethylnaphthalene, is provided in which 2,6-dimethylnaphthalene of high purity is obtained from a mixture of dimethylnaphthalene isomers with a high yield, by means of a combined process of column melt crystallization and sweating operation.
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Page/Page column 4-8
(2008/06/13)
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- Method for separating and purifying 2,6-dimethylnaphthalene
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A method for separating and purifying 2,6-dimethylnaphthalene, is provided in which 2,6-dimethylnaphthalene of high purity is obtained from a mixture of dimethylnaphthalene isomers with a high yield, by means of a combined process of column melt crystallization and sweating operation.
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Page/Page column 14-17
(2008/06/13)
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- NOVEL PROCESS FOR PREPARATION OF 2,6-DIALKYLNAPHTHALENE
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The present invention relates to a novel method for preparing 2,6-dialkylnaphthalene with high selectivity and high yield using entirely novel starting materials through alkylation and cyclodehydration without necessitating separation or purification of isomers, which has been a problem of the conventional method, and particularly to a method comprising the steps of (a) preparing an intermediate by alkylating an aromatic compound with an alkene compound in an equivalent ratio in the presence of a catalyst and (b) preparing 2,6-dialkylnaphthalene through cyclodehydration of the intermediate.
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Page/Page column 7-8
(2008/06/13)
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- Novel process for preparation of 2,6-dialkyltetralin
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The present invention provides a novel process for highly selective preparation of 2,6-dialkyltetralin, a key precursor for 2,6-dimethylnaphthalene (2,6-DMN), which does not require an extra step for purifying various isomers obtained from the conventional processes for 2,6-DMN. The present invention is advantageous to improve the synthetic yield, to simplify the operation and thus to reduce the production cost, since different starting materials and different pathways are exploited and thus the additional steps are not necessary.
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Page/Page column 9
(2008/06/13)
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- Regioselective synthesis of 2,6-dimethyltetralin: Key precursor to 2,6-dimethylnaphthalene
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A novel regioselective synthesis for 2,6-dimethyltetralin (2,6-DMT), a key precursor to 2,6-dimethylnaphthalene (2,6-DMN), is described. The synthesis comprises the following three steps; the Heck reaction between commercially available 4-bromotoluene and 3-methyl-3-buten-1-ol, the catalytic reduction of the coupling products, and the acid-catalyzed cyclization of the alcohol intermediate. The process has an advantage over the established processes in that 2,6-DMT is obtained as the only isomer, and the isomerization and/or the complicated separation and purification steps are not required to produce pure 2,6-DMT. 2,6-DMN could be also obtained as a major product depending on the cyclization conditions.
- Byung, Hyun Kim,Jong, Gil Lee,Woon, Ki Kim,Young, Gyu Kim
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p. 814 - 817
(2012/12/26)
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- Selective methylation catalyst, method of catalyst manufacture and methylation process
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Novel catalysts and processes in accordance with the invention can accomplish high selectivity and conversion of naphthalenic compounds such as the conversion of methylnaphthalene (2-MN) or naphthalene to 2,6-dimethylnaphthalene (2,6-DMN). The catalysts are prepared by treating, for example, a ZSM-5-type material with iron in the presence of a halogen such as a fluoride. The resulting catalyst includes iron, as well as a significant portion of aluminum present in the ZSM-5-type starting material. Processes for using the catalysts also are disclosed.
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Page/Page column 5
(2008/06/13)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Method for manufacturing 2,6-Dimethylnaphthalene
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The present invention provides a method for manufacturing a highly pure 2,6-dimethylnaphthalene having a purity of 99% or more even when a mixture of dimethylnaphthalene isomers containing 5 wt% or more of 2,7-dimethylnaphthalate is used as a feedstock. The method for manufacturing 2,6-dimethylnaphthalene comprises a step of performing crystallization and solid-liquid separation of a liquid primarily containing dimethylnaphthalene isomers so that the liquid is separated into a cake containing the dimethylnaphthalene isomers and a mother liquor, and a step of performing separation/purification of the cake. In the method described above, the crystallization and the solid-liquid separation are performed under the condition in which the ratio of the content of 2,6-dimethylnaphthalene in the mother liquor to that of 2,7-dimethylnaphthalene therein is not less than 1 so that the content of 2,6-dimethylnaphthalene in the cake is 60% or more and that the content of 2,7-dimethylnaphthalene therein is 6.5% or less. As a result, a highly pure 2,6-dimethylnaphthalene is obtained by performing the separation/purification of the cake.
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- Methyl and Dimethyl Derivatives of Tetrathionaphthalene and Tetraselenonaphthalene as Novel Electron Donors
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Monomethyl and dimethyl tetrathionaphthalenes and tetraselenonaphthalenes have been developed as modified electron donors. Introduction of methyl groups is very helpful in enhancing the inherent low solubilities of the parent compounds. In the cyclic voltammograms, they show two reversible redox waves, whose first and second oxidation potentials are gradually lowered with the increasing number of the introduced methyl groups. They all are able to form charge-transfer complexes with tetracyanoquinodimethane. Irrespective of the chalcogen kind of the donor, the complexes of the dimethyl derivatives are conductive, while those of the monomethyl derivatives are insulating. The different conductivities are explained by the difference of their crystal structures, which are studied by infrared spectroscopy.
- Kodama, Takashi,Kodani, Mie,Takimiya, Kazuo,Aso, Yoshio,Otsubo, Tetsuo
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p. 287 - 292
(2007/10/03)
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- Further studies of the thermal and photochemical Diels-Alder reactions of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with naphthalene and some substituted naphthalenes
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MeTAD thermally reacted with naphthalene (2) and methylated naphthalenes to give equilibrium mixtures of starting materials and [4 + 2] cycloadducts. Methyl substitution on the naphthalene ring generally increased both the amount of cycloadduct formed and the rate of cycloaddition relative to 2. The isolated cycloadducts were all thermally labile and quantitatively reverted to the parent naphthalene in the presence of 2,3-dimethyl-2-butene as a trap for liberated MeTAD. The rates of the cycloreversion reactions were affected by substitution patterns but not appreciably by solvent. A mechanism for the cycloaddition reaction is presented that proposes the involvement of a charge-transfer complex. Photochemically, MeTAD demonstrated lower regioselectivity in its reactions with substituted naphthalenes relative to the corresponding thermal reactions.
- Breton, Gary W.,Newton, Kristy A.
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p. 2863 - 2869
(2007/10/03)
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- Bifunctional catalysis of Mo/HZSM-5 in the dehydroaromatization of methane to benzene and naphthalene XAFS/TG/DTA/ MASS/FTIR characterization and supporting effects
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The direct conversion of methane to aromatics such as benzene and naphthalene has been studied on a series of Mo-supported catalysts using HZSM-5, FSM-16, mordenite, USY, SiO2, and Al2O3 as the supporting materials. Among all the supports used, the HZSM-5-supported Mo catalysts exhibit the highest yield of aromatic products, achieving over 70% total selectivity of the hydrocarbons on a carbon basis at 5-12% methane conversion at 973 K and 1 atm. By contrast, less than 20% of the converted methane is transformed to hydrocarbon products on the other Mo-supported catalysts, which are drastically deactivated, owing to serious coke formation. The XANES/EXAFS and TG/DTA/mass studies reveal that the zeolite-supported Mo oxide is endothermally converted with methane around 955 K to molybdenum carbide (Mo2C) cluster (Mo-C, C.N. = 1,R = 2.09 A; Mo-Mo, C.N. = 2.3-3.5; R = 2.98 A), which initiates the methane aromatization yielding benzene and naphthalene at 873-1023 K. Although both Mo2C and HZSM-5 support alone have a very low activity for the reaction, physically mixed hybrid catalysts consisting of 3 wt% Mo/SiO2 + HZSM-5 and Mo2C + HZSM-5 exhibited a remarkable promotion to enhance the yields of benzene and naphthalene over 100-300 times more than either component alone. On the other hand, it was demonstrated by the IR measurement in pyridine adsorption that the Mo/HZSM-5 catalysts having the optimum SiO2/Al2O3 ratios, around 40, show maximum Broensted acidity among the catalysts with SiO2/Al2O3 ratios of 20-1900. There is a close correlation between the activity of benzene formation in methane aromatization and the Broensted acidity of Mo/HZSM-5, but not Lewis aciditiy. It was found that maximum benzene formation was obtained on the Mo/HZSM-5 having SiO2/Al2O3 ratios of 20-49, but substantially poor activities on those with SiO2/Al2O3 ratios smaller and higher than 40. The results suggest that methane is dissociated on the molybdenum carbide cluster supported on HZSM-5 having optimum Broensted acidity to form CHx (x > 1) and C2-species as the primary intermediates which are oligomerized subsequently to aromatics such as benzene and naphthalene at the interface of Mo2C and HZSM-5 zeolite having the optimum Broensted acidity. The bifunctional catalysis of Mo/HZSM for methane conversion towards aromatics is discussed by analogy with the promotion mechanism on the Pt/Al2/O3 catalyst for the dehydro-aromatization of alkanes.
- Liu, Shetian,Wang, Linsheng,Ohnishi, Ryuichiro,Ichikawa, Masaru
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p. 175 - 188
(2007/10/03)
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- Characterization of the combustion products of polyethylene
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Polyethylene (PE) was burned in a tube-type furnace with an air flow at a temperature of 600~900°C. Combustion products were collected with glass wool, glass fiber filter, and XAD-2 adsorbent. The analysis of the products was performed with GC-FID and GC-MSD. At low temperature, hydrocarbons were the major components, while at higher temperature the products were composed of polycyclic aromatic hydrocarbons. With the high performance of the Hewlett-Packard 6890GC-5973MSD, more compounds were identified in comparison with previous studies.
- Piao, Mingjun,Chu, Shaogang,Zheng, Minghui,Xu, Xiaobai
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p. 1497 - 1512
(2007/10/03)
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- Dehydrocyclization of polysubstituted cyclic organic compounds over copper aluminum borate
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A dehydrocyclization process is described for producing polynuclear organic compounds by contacting a starting organic material having at least one ring moiety comprising at least two adjacent ring carbon atoms each bonded to an independently selected monovalent radical comprising at most about eight carbon atoms provided at least one of the monovalent hydrocarbon radicals comprises more than one carbon atom with a crystalline copper aluminum borate catalyst. The preferred catalyst comprises at least one member selected from the group consisting of (a) crystalline copper aluminum borate and (b) zero valent copper on a support comprising at least one member selected from the group consisting of Al4 B2 O9 and the crystalline copper aluminum borate, the zero valent copper on the support being formed by the reduction of the crystalline copper aluminum borate. The process is conducted under conditions sufficient to effect cyclization between (i) a carbon atom of one of the radicals and (ii) a carbon atom of the other radical forming a dehydrocyclization product comprising a polynuclear compound wherein the new ring comprises at least 5 carbon atoms.
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- SHAPE SELECTIVE DISPROPORTIONATION OF METHYLNAPHTHALENE ON ZSM-5 CATALYST
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The conversion of 2-methylnaphthalene (2-MN) was studied at atmospheric pressure in a flow-type fixed bed reactor using H-Y, H-beta, H-mordenite, H-ZSM-5, H-ZSM-11 and H-ZSM-48 as catalysts.H-Y and H-beta exhibited high activities for disproportionation and isomerization of 2-MN.H-Mordenite and zeolites having medium size pores were active for the conversion of 2-MN which was mainly isomerized to 1-MN.The low disproportionation activities of these zeolites resulted from their shape selective properties.Disproportionation of 2-MN on the zeolite catalysts gave 2,6- and 2,7-dimethylnaphthalenes (DMN) in higher proportions than the thermodynamically attainable level.H-ZSM-5 was the most selective catalyst to produce these DMN isomers among the zeolite catalysts tested, although 2,7-DMN was formed in a higher proportion than 2,6-DMN.On H-mordenite catalyst, 2,6-DMN was more selectively formed than 2,7-DMN.The selectivity for 2,6-DMN against 2,7-DMN increased with increasing SiO2/Al2O3 ratio of H-mordenite.It is suggested that the composition of DMN isomers produced by disproportionation of 2-MN depends on the acid strength as well as on the shape selective properties of zeolites used.
- Kikuchi, Eiichi,Mogi, Yasuhiro,Matsuda, Takeshi
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p. 909 - 919
(2007/10/02)
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- Efficiencies of photoinduced electron-transfer reactions: Role of the Marcus inverted region in return electron transfer within geminate radical-ion pairs
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In photoinduced electron-transfer processes the primary step is conversion of the electronic energy of an excited state into chemical energy retained in the form of a redox (geminate radical-ion) pair (A + D →hν A?-/D?+). In polar solvents, separation of the geminate pair occurs with formation of free radical ions in solution. The quantum yields of product formation, from reactions of either the free ions, or of the geminate pair, are often low, however, due to the return electron transfer reaction (A?-/D?+ → A + D), an energy-wasting step that competes with the useful reactions of the ion pair. The present study was undertaken to investigate the parameters controlling the rates of these return electron transfer reactions. Quantum yields of free radical ion formation were measured for ion pairs formed upon electron-transfer quenching of the first excited singlet states of cyanoanthracenes by simple aromatic hydrocarbon donors in aceonitrile at room temperature. The free-ion yields are determined by the competition between the rates of separation and return electron transfer. By assuming a constant rate of separation, the rates of the return electron transfer process are obtained. These highly exothermic return electron transfer reactions (-ΔG-et = 2-3 eV) were found to be strongly dependent on the reaction exothermicity. The electron-transfer rates showed a marked decrease (ca. 2 orders of magnitude in this ΔG-et range) with increasing exothermicity. This effect represents a clear example of the Marcus "inverted region". Semiquantum mechanical electron-transfer theories were used to analyze the data quantitatively. The electron-transfer rates were found also to depend upon the degree of charge delocalization within the ions of the pair, which is attributed to variations in the solvent reorganization energy and electronic coupling matrix element. Accordingly, mostly on the basis of redox potentials, one can vary the quantum yield of free-ion formation from a few percent to values approaching unity. Use of a strong donor with a strong acceptor to induce reactions based on electron transfer is likely to be inefficient because of the fast return electron transfer in the resulting low-energy ion pair. A system with the smallest possible driving force for the initial charge-separation reaction results in a high-energy, and therefore long-lived ion pair, which allows the desired processes to occur more efficiently. The use of an indirect path based on secondary electron transfer, a concept called "cosensitization", results in efficient radical-ion formation even when the direct path results in a very low quantum yield.
- Gould, Ian R.,Ege, Deniz,Moser, Jacques E.,Farid, Samir
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p. 4290 - 4301
(2007/10/02)
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- Shape Selective Catalysis by ZSM-5 in Disproportionation of 2-Methylnaphthalene
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Disproportionation of methylnaphthalene (MN) was carried out on ZSM-5 catalysts.The external acid sites were eliminated by dealumination with (NH4)2SiF6.The dealuminated ZSM-5 gave 2,6- and 2,7-dimethylnaphthalene (DMN) from disproportionation of 2-methylnaphthalene (MN), due to its shape selective property.
- Matsuda, Takeshi,Yogo, Katsunori,Mogi, Yashuhiro,Kikuchi, Eiichi
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p. 1085 - 1088
(2007/10/02)
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- Electrophilic Aromatic Substitution. Part 35. Deviations from Additivity of Methyl Substituent Effects in Detritiation of Dimethylnaphthalenes: the Effect of Electron Supply on Bond Fixation
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Rate coefficients have been measured for protiodetritiation in anhydrous trifluoroacetic acid at 70 deg C of all positions of 1,3-, 1,4-, 1,5-, 1,8-, 2,3-, 2,6-, and 2,7-dimethylnaphthalenes.The derived partial rate factors show up to 10-fold departure from those calculated on the basis of additivity of the individual methyl substituent effects.Of the seventeen positions examined, all but three show reactivity which is greater than that calculated.The results point to a decrease in bond fixation in dimethylnaphthalenes compared to monomethylnaphthalenes, probably arising either from the increased electron supply in the former or from a sterically facilitated change in the shape of the naphthalene nucleus.Detritiation of 1,8-dimethylnaphthalene is accompanied by isomerisation to 1,7-dimethylnaphthalene due almost certainly to a sterically accelerated 1,2-methyl shift; this shift (which is the first observed during hydrogen exchange studies) accounts for discrepancies between previous measurements of the exchange rate of the (relatively unreactive) 3-position of 1,8-dimethylnaphthalene.The kinetics show that surface-catalysed protiodemethylation accompanies detritiation of 1,4-dimethylnaphthalene and this is aided by the high stability of the intermediate for this ipso-substitution.
- Neary, Adrian P.,Taylor, Roger
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p. 1233 - 1238
(2007/10/02)
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- Transanular Interactions in Phanes, XXV. Structurally Isomeric Naphthalenoparacyclophanes
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The structurally isomeric naphthalenoparacyclophanes 1, 2 and 3, having 1,4-, 1,5- and 2,6-bridged naphthalene moieties, respectively, were synthesized via the corresponding dithiaphanes 8, 9, 10.The photolytic desulfurization of 10 and the sulfur dioxide extrusion via vapour phase pyrolysis of the corresponding disulfone 11 to the highly strained 3 clearly demonstrate the limits of these preparative ring contraction methods.
- Haenel, Matthias W.
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p. 1425 - 1436
(2007/10/02)
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- Process for preparing dimethyl naphthalene
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A process for preparing dimethyl naphthalenes, which comprises heating a compound, such as methyl-4-(p-tolyl) butane, methyl-4-(p-tolyl)butene or methyl-4-(p-tolyl)butadiene, in the presence of a cyclization-dehydrogenation catalyst.
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