- Phosphate modified ZSM-5 for the shape-selective synthesis of para-diethylbenzene: Role of crystal size and acidity
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Pore engineered ZSM-5 zeolite in extrudate form was prepared and used as shape-selective catalyst for vapor phase ethylation of ethylbenzene to selectively form para-diethylbenzene. The physico-chemical properties of the catalyst were established by XRD, N2 sorption, FTIR, FESEM, NH 3-TPD and 31P MAS NMR. Alkylation of ethylbenzene with ethanol was carried out in a continuous, down-flow, tubular reactor, at atmospheric pressure and H2 as a carrier gas in vapor phase. Effect of silica to alumina ratio (SAR), crystal size, acidity of phosphate modified ZSM-5, stepwise phosphate modification and reaction conditions were studied in detail. ZSM-5 with SAR 187 was found to contain optimum acidity for phosphate modification to achieve good conversion and high selectivity for p-diethylbenzene. Under optimized reaction conditions, viz. temperature = 380 °C, ethylbenzene:ethanol mole ratio = 4:1, WHSV = 3 h-1, H 2/reactants = 2, 5PZSM-5 W catalyst gave 22.8% of ethylbenzene conversion with ~98% selectivity for para-diethylbenzene.
- Hodala, Janardhan L.,Halgeri, Anand B.,Shanbhag, Ganapati V.
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- Shape Selectivity of ZSM-5 Type Zeolite for Alkylation of Ethylbenzene with Ethanol
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The alkylation of ethylbenzene with ethanol on ZSM-5 zeolites was studied at 673 K.The primary product in this alkylation on HZSM-5 catalyst was only p-diethylbenzene because of the transition-state selectivity.Therefore, the isomerization of p-diethylbenzene has to be restrained for the selective formation of p-diethylbenzene.The modified HZSM-5 catalysts with oxide of magnesium, phosphorus or boron showed much higher para-selectivity than the parent HZSM-5.The modification reduced not only the effective pore dimension of HZSM-5 but also the amount of strong acid sites.We claim that the absence of strong acid sites is necessary rather than the narrowness of pores for the suppression of the isomerization of p-diethylbenzene produced as a primary product.
- Kim, Jong-Ho,Namba, Seitaro,Yashima, Tatsuaki
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- para-Selectivity of a Highly Siliceous ZSM-5 Zeolite Modified with Arsenic(III)
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A highly siliceous ZSM-5 zeolite treated with AsCl3 vapour at 673 K exhibited a high para-selectivity (94.1percent) for the alkylation of ethylbenzene with ethanol.
- Kim, Jong-Ho,Yamagishi, Kouji,Namba, Seitaro,Yashima, Tatsuaki
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- Addition of arenes to ethylene and propene catalyzed by ruthenium
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TpRuII(CO)(Me)(NCMe) (Tp = hydridotris(pyrazolyl)borate) serves as a catalyst precursor for the conversion of benzene and ethylene or propene to alkylaromatic products. The reaction proceeds via the formation of the active catalyst TpRu(CO)(Ph)(NCMe) and is mildly selective for linear propylbenzene over isopropylbenzene. Copyright
- Lail, Marty,Arrowood, Benjamin N.,Gunnoe, T. Brent
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- The influence of the external acidity of H-ZSM-5 on its shape selective properties in the disproportionation of ethylbenzene
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The shape selectivity of H-ZSM-5 in the disproportionation of ethylbenzene was investigated, using a set of samples with the same Si/Al ratio, but different particle sizes in the range from 0.1 to 80 μm. The number of external acid sites of each sample was measured gravimetrically by the adsorption of 2,6-dimethylpyridine. The data were correlated with the results of catalytic experiments. Conversion and product distribution are strongly dependent on the external acidity which in turn correlates well with the particle size. An estimate for the diffusion coefficient could be obtained by fitting the effectiveness factor for the different particle sizes.
- Melson, Sabine,Schueth, Ferdi
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- Effects of Dry-air Calcination on the Physico-chemical and Catalytic Properties of HZSM-5 Zeolite
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A series of HZSM-5 zeolites has been prepared by dry-air calcination, in the range 833 to 1163 K, of samples from a single preparation of NH4ZSM-5 containing 5.5 framework AlT atoms per unit cell.A similar series of HZSM-5 zeolites has been prepared from NH4ZSM-5 that had been bound with colloidal silica (Ludox) prior to dry-air calcination.The zeolites were characterised using mid-IR spectroscopy, 27Al magic-angle-spinning nuclear magnetic resonance (27Al MAS NMR) and temperature-programmed desorption (TPD) of NH3.It was shown that the zeolites are highly crystalline and that extensive structural dealumination does not occur at calcination temperatures below ca. 1000 K.Framework aluminium contents determined by 27Al MAS NMR are considered to be a better measure of acid-site concentration that those given by TPD of NH3.The activity of HZSM-5 zeolites as catalysts for ethylbenzene conversion at 573 K, to ethene, benzene and diethylbenzene, was only slightly suppressed by binding with silica.Reaction is believed to proceed by a dealkylation-alkylation mechanism; a maximum in activity for unbound HZSM-5 at AlT = 2.8 suggests synergic interaction between framework and non-framework aluminium atoms.The conversion of propane at 808 K, to mainly methane, ethene and propene, showed an activity pattern closely similar to that of ethylbenzene.
- Rudham, Robert,Winstanley, Alastair W.
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- Metal-free catalysis of sustainable Friedel-Crafts reactions: Direct activation of benzene by carbon nitrides to avoid the use of metal chlorides and halogenated compounds
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The use of mesoporous graphitic C3N4 for the activation of benzene permitted to perform more sustainable Friedel-Crafts reactions by allowing to directly use carboxylic acids, alcohols and even quaternary ammoniums or urea as electrophiles. The Royal Society of Chemistry 2006.
- Goettmann, Frederic,Fischer, Anna,Antonietti, Markus,Thomas, Arne
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- Highly selective synthesis of para-diethylbenzene by alkylation of ethylbenzene with diethyl carbonate over boron oxide modified HZSM-5
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A series of B2O3/HZSM-5 catalysts were prepared by impregnation of HZSM-5 zeolites with triethyl borate, trimethyl borate and boric acid. The selective synthesis of para-diethylbenzene by alkylation of ethylbenzene with diethyl carbonate was carried out over the B2O3/HZSM-5 catalysts. The physicochemical properties of the catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, Fourier-transform infrared spectroscopy with pyridine adsorption and NH3 temperature programmed desorption. The characterization results indicated that the 15% B2O3/HZSM-5 catalyst prepared by using triethyl borate as the precursor exhibited an outstanding shape-selectivity along with a high catalytic activity in alkylation of ethylbenzene with diethyl carbonate. This might be ascribed to the large molecular size of triethyl borate, which would lead to the formation of B2O3 on the external surface of HZSM-5 zeolite and preserve the acid sites in the micropores of HZSM-5 zeolite. By contrast, the B2O3/HZSM-5 catalysts prepared by using trimethyl borate or boric acid led to the severe reduction in catalytic activity, which was attributed to the decrease in the amount of the total acid sites caused by the blockage of the partial pores of HZSM-5 zeolite.
- Xue, Bing,Zhang, Gen,Liu, Na,Xu, Jie,Shen, Qingming,Li, Yongxin
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- The Thermal Cycloaddition of Dispirodeca-4,9-diene to Isolated Carbon-Carbon Multiple Bonds
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The cycloadditions of dispirodeca-4,9-diene (1) to isolated carbon-carbon multiple bonds have proceeded in two different modes, giving dispirododeca-4,11-diene and tricyclo(6.4.0.03,6>dodeca-2,7-diene derivatives.Mono- and 1,2-disubstituted olefins and acetylenes gave the former adducts, whereas 1,1-disubstituted olefins gave the latter, as the major products.Evidence for the intermediacy of biradicals is provided.The observed difference in the mode of the cycloaddition is explained in terms of the stereoelectronic and/or steric effect in the transition state for the cyclization of the intermediate.The addition of 1 to tetracyanoethylene (TCNE) in wet acetone has proceeded via a zwitterionic intermediate(s), giving a 1:1:1 adduct of 1, TCNE, and water.
- Shibata, Tohru,Tsuji, Takashi,Nishida, Shinya
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- Effects of crystallinity of ZSM-5 zeolite on para-selective tert-butylation of ethylbenzene
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Highly crystalline ZSM-5 zeolites are important for para-selective alkylation of alkyl aromatics, because they carry few external acid sites for isomerization of p-dialkyl products. Such zeolites (Si/Al = 25, 50, and 75) were synthesized in a fluoride medium between pH 4 and 6. Their crystallinities, crystal sizes, and surface areas were higher than those of a commercial ZSM-5 zeolite. Their para selectivities in alkylation were tested for vapor-phase tert-butylation of ethylbenzene between 200 and 400 °C. As expected, all the catalysts showed more than 90% para selectivity. At 300 °C, ethylbenzene conversion decreased in the order ZSM-5(25, commercial) > ZSM-5(25) > ZSM-5(50) > ZSM-5(75). The catalysts had weak, medium, and strong acid sites, but all the acid sites of ZSM-5(75) were weaker than those of ZSM-5(25) and ZSM-5(50). The high activity of commercial ZSM-5 was caused by its strong acid sites being stronger than those of the synthesized zeolites. Although the activity of the commercial catalyst was higher than those of the present catalysts, the selectivity for 4-t-butylethylbenzene (4-t-BEB) was low. The optimum feed ratio (ethylbenzene:t-butyl alcohol) was 2:1 and the feed rate was 1.65 h-1 for high ethylbenzene conversion and 4-t-BEB selectivity. Time-on-stream studies showed slow catalyst deactivation. Highly crystalline ZSM-5 zeolites are therefore better than a commercial zeolite for para-selective alkylation of alkyl aromatics. They do not require much post-modification for high para selectivity. A fluoride medium is therefore better than an alkaline medium for obtaining highly crystalline para-selective ZSM-5 zeolites.
- Pushparaj, Hemalatha,Mani, Ganesh,Muthiahpillai, Palanichamy,Velayutham, Murugesan,Park, Yong-Ki,Choi, Won Choon,Jang, Hyun Tae
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- Zeolite SSZ-53: An extra-large-pore zeolite with interesting catalytic properties
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(Figure Presented) Wide pores for wide applications: The catalytic properties of SSZ-53, an extra-large-pore high-silica zeolite, were explored by using ethylbenzene disproportionation and the isomerization and hydrocracking of n-decane as test reactions. High activity together with a very open channel system render this zeolite an attractive candidate as catalyst for applications in petroleum refining.
- Tontisirin, Supak,Ernst, Stefan
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- Crystal dimension of ZSM-5 influences on para selective disproportionation of ethylbenzene
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Crystal size and crystal dimensions are vital role in shape selective feature. Para selective disproportionation of EthylBenzene (Dip-EB) was investigated over ZSM-5 synthesized in acidic medium. The catalysts were prepared by hydrothermal process with va
- Hariharan, Srinivasan,Palanichamy, Muthaiahpillai
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- Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
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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
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p. 3685 - 3690
(2021/05/31)
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- Selective hydrodeoxygenation of hydroxyacetophenones to ethyl-substituted phenol derivatives using a FeRu?SILP catalyst
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The selective hydrodeoxygenation of hydroxyacetophenone derivatives is achieved opening a versatile pathway for the production of valuable substituted ethylphenols from readily available substrates. Bimetallic iron ruthenium nanoparticles immobilized on an imidazolium-based supported ionic liquid phase (Fe25Ru75?SILP) show high activity and stability for a broad range of substrates without acidic co-catalysts. This journal is
- Bordet, Alexis,Goclik, Lisa,Leitner, Walter,Offner-Marko, Lisa
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supporting information
p. 9509 - 9512
(2020/09/02)
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- Guaiacol demethoxylation catalyzed by Re2O7 in ethanol
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Re2O7 is used to convert guaiacol in alcohols at 280–320 °C. In ethanol, guaiacol is deoxygenated and alkylated, and the major products are phenol and alkylphenols (including ethylphenol, diethylphenol, diisopropylphenol, di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol), accounting for 97 mol% of all products after 6 hour reaction at 320 °C. Both catechol and phenol are the intermediates of guaiacol demethoxylation. Among the substituents, ethyl is directly provided by ethanol while isopropyl and tert-butyl are formed by the addition of methyl to ethyl step by step. In addition, Re2O7 has negligible activity for the saturation of benzene ring so it does not cause considerable over-consumption of reductant. The actual catalyst for guaiacol demethoxylation is likely a ReIV?VI species.
- Yan, Fei,Sang, Yushuai,Bai, Yunfei,Wu, Kai,Cui, Kai,Wen, Zhe,Mai, Fuhang,Ma, Zewei,Yu, Linhao,Chen, Hong,Li, Yongdan
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p. 231 - 237
(2019/08/12)
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- Unraveling the Homologation Reaction Sequence of the Zeolite-Catalyzed Ethanol-to-Hydrocarbons Process
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Although industrialized, the mechanism for catalytic upgrading of bioethanol over solid-acid catalysts (that is, the ethanol-to-hydrocarbons (ETH) reaction) has not yet been fully resolved. Moreover, mechanistic understanding of the ETH reaction relies heavily on its well-known “sister-reaction” the methanol-to-hydrocarbons (MTH) process. However, the MTH process possesses a C1-entity reactant and cannot, therefore, shed any light on the homologation reaction sequence. The reaction and deactivation mechanism of the zeolite H-ZSM-5-catalyzed ETH process was elucidated using a combination of complementary solid-state NMR and operando UV/Vis diffuse reflectance spectroscopy, coupled with on-line mass spectrometry. This approach establishes the existence of a homologation reaction sequence through analysis of the pattern of the identified reactive and deactivated species. Furthermore, and in contrast to the MTH process, the deficiency of any olefinic-hydrocarbon pool species (that is, the olefin cycle) during the ETH process is also noted.
- Chowdhury, Abhishek Dutta,Lucini Paioni, Alessandra,Whiting, Gareth T.,Fu, Donglong,Baldus, Marc,Weckhuysen, Bert M.
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supporting information
p. 3908 - 3912
(2019/02/20)
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- Production of p-Methylstyrene and p-Divinylbenzene from Furanic Compounds
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A four-step catalytic process was developed to produce p-methylstyrene from methylfuran, a biomass-derived species. First, methylfuran was acylated over zeolite H-Beta with acetic anhydride. Second, the acetyl group was reduced to an ethyl group with hydrogen over copper chromite. Third, p-ethyltoluene was formed through Diels–Alder cycloaddition and dehydration of 2-ethyl-5-methyl-furan with ethylene over zeolite H-Beta. Dehydrogenation of p-ethyltoluene to yield p-methylstyrene completes the synthesis but was not investigated because it is a known process. The first two steps were accomplished in high yield (>88 %) and the Diels–Alder step resulted in a 67 % yield of p-ethyltoluene with a 99.5 % selectivity to the para isomer (final yield of 53.5 %). The methodology was also used for the preparation of p-divinylbenzene. It is shown that acylation of furans over H-Beta zeolites is a highly selective and high-yield reaction that could be used to produce other valuable molecules from biomass-derived furans.
- Koehle, Maura,Sara?i, Erisa,Dauenhauer, Paul,Lobo, Raul F.
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- A kind of ethylene and benzene one method for two-step synthesis of ethylbenzene
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The invention discloses a method for synthesizing diethylbenzene from ethylene and benzene by a one-step process, which comprises the stages of pretreatment, reaction and after-treatment. The method comprises the following steps: pretreating reactants, sending into an alkylation reactor, and sending into a benzene recovery system, an ethylbenzene rectification system and a diethylbenzene rectification system, thereby obtaining mixed diethylbenzene with certain purity. In order to sufficiently utilize the utilization ratio of benzene, the meta-diethylbenzene enrichment solution and para-diethylbenzene enrichment solution can be recovered, the main product is highly meta/para- mixed diethylbenzene, and the byproducts are ethylbenzene, meta-diethylbenzene enrichment solution and para-diethylbenzene enrichment solution. The method has the advantages of simple production process and high utilization ratio of raw materials, and can lower the production cost of diethylbenzene.
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Paragraph 0037; 0038
(2017/03/28)
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- Method for simultaneously synthesizing methyl-ethylbenzene and diethylbenzene by virtue of one-step method
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The invention relates to a method for simultaneously synthesizing methyl-ethylbenzene and diethylbenzene by virtue of a one-step method. Ethylene, benzene and methylbenzene are taken as raw materials to perform an alkylation reaction so as to synthesize methyl-ethylbenzene and diethylbenzene in one step. The method comprises a pretreatment stage, a reaction stage and an aftertreatment stage. In the method, one reaction system is adopted, and alkylation reaction and aftertreatment are sequentially performed so as to separate components, so that target products are obtained, and thus one-step simultaneous synthesis of methyl-ethylbenzene and diethylbenzene is realized; the problem that two independent devices are respectively used for production in a traditional production process is avoided, and the whole reaction process is convenient and rapid; the yields of different components can be effectively adjusted by adjusting different proportions of raw materials, and unreacted benzene and methylbenzene and the ethylbenzene generated in a reaction process are separated and recycled to serve as raw materials once again, so that the production cost is greatly saved, and meanwhile, the method can adapt to variations of the market to the greatest extent.
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Paragraph 0051-0065
(2016/12/22)
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- Temperature-controlled phase-transfer hydrothermal synthesis of MWW zeolites and their alkylation performances
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MWW zeolites have been synthesized with hexamethyleneimine/aniline as the structure-directing/ promoting agent. As structure-promoting agent, aniline contributes to the crystallization of MWW zeolites without being trapped within zeolites. Meanwhile the t
- Xing, Enhui,Shi, Yanchun,Xie, Wenhua,Zhang, Fengmei,Mu, Xuhong,Shu, Xingtian
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p. 29707 - 29717
(2018/06/04)
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- Enhancing activity without loss of selectivity - Liquid-phase alkylation of benzene with ethylene over MCM-49 zeolites by TEAOH post-synthesis
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As-synthesized and calcined MCM-49 zeolites were post-synthesized by tetraethylammonium hydroxide to tailor their morphology, texture properties, acid sites and catalytic performances. With post-synthesis by tetraethylammonium hydroxide, both as-synthesiz
- Shi, Yanchun,Xing, Enhui,Xie, Wenhua,Zhang, Fengmei,Mu, Xuhong,Shu, Xingtian
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p. 135 - 144
(2015/09/28)
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- Synthesis, characterization and application of MCM-22 zeolites via a conventional HMI route and temperature-controlled phase transfer hydrothermal synthesis
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With less environmental and economical impact, temperature-controlled phase transfer hydrothermal synthesis of MWW zeolites was realized with hexamethyleneimine as a structure-directing agent and aniline as a structure-promoting agent. MCM-22 zeolite, synthesized via temperature-controlled phase transfer hydrothermal synthesis, is nearly identical concerning chemical composition and structure, and possesses nearly identical properties with respect to porosity, Si/Al ratio, thermal behavior and catalytic activity at 200°C, compared with that made from conventional synthesis with hexamethyleneimine as the only template.
- Xing, Enhui,Shi, Yanchun,Xie, Wenhua,Zhang, Fengmei,Mu, Xuhong,Shu, Xingtian
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p. 8514 - 8522
(2015/03/05)
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- Size-controlled synthesis of MCM-49 zeolites and their application in liquid-phase alkylation of benzene with ethylene
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Size-controlled synthesis of MCM-49 zeolites was achieved via topology reconstruction from NaY zeolites with different sizes. SEM images showed that the sizes of the reconstructed H-MCM-49 zeolites were controlled by those of the parent NaY zeolites. Smal
- Shi, Yanchun,Xing, Enhui,Xie, Wenhua,Zhang, Fengmei,Mu, Xuhong,Shu, Xingtian
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p. 13420 - 13429
(2015/02/19)
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- TRANSITION METAL CATALYSTS FOR C-O HYDROGENOLYSIS AND HYDRODEOXYGENATION
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Phosphoranimide-metal catalysts and their role in C—O bond hydrogenolysis and hydrodeoxygenation (HDO) are disclosed. The catalysts comprise of first row transition metals such as nickel, cobalt and iron. The catalysts have a metal to anionic phosphoranimide ratio of 1:1 and catalyze C—O bond hydrogenolyses of a range of oxygen-containing organic compounds under lower temperature and pressure conditions than those commonly used in industrial hydrodeoxygenation.
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Paragraph 0191
(2014/07/08)
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- Reduction of alkenes catalyzed by copper nanoparticles supported on diamond nanoparticles
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Copper nanoparticles (Cu NPs) supported on diamond nanoparticles (D NPs) previously purified by Fenton treatment (Cu/D) followed by annealing with hydrogen (Cu/DH) are highly efficient and reusable heterogeneous catalysts for hydrogenation of styrene to ethylbenzene with the minimum productivity value of 30617 cycles. The Royal Society of Chemistry.
- Dhakshinamoorthy, Amarajothi,Navalon, Sergio,Sempere, David,Alvaro, Mercedes,Garcia, Hermenegildo
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supporting information
p. 2359 - 2361
(2013/07/05)
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- Platinum(II)-catalyzed ethylene hydrophenylation: Switching selectivity between alkyl- and vinylbenzene production
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The series of PtII complexes [(xbpy)Pt(Ph)(THF)] [BAr′4] (xbpy =4,4′-X-2,2′-bipyridyl, X = OMe, tBu, H, Br, CO2Et, NO2; Ar′ = 3,5-bis(trifluoromethyl)phenyl) are catalyst precursors for ethylene hydrophenylation. The bipyridyl substituent provides a tunable switch for catalyst selectivity that also has significant influence on catalyst activity and longevity. Less electron donating 4,4′-substituents increase the propensity toward styrene formation over ethylbenzene.
- McKeown, Bradley A.,Gonzalez, H. Emanuel,Friedfeld, Max R.,Brosnahan, Anna M.,Gunnoe, T. Brent,Cundari, Thomas R.,Sabat, Michal
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p. 2857 - 2865
(2013/06/26)
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- PtII-catalyzed ethylene hydrophenylation: Influence of dipyridyl chelate ring size on catalyst activity and longevity
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Expansion of the dipyridyl ligand from a five- to six-membered chelate for PtII-catalyzed ethylene hydrophenylation provides an enhancement of catalyst activity and longevity. Mechanistic studies of [(dpm)Pt(Ph)(THF)] [BAr′4] [dpm = 2,2′-dipyridylmethane, and Ar′ = 3,5-(CF3)2C6H3] attribute the improved catalytic performance at elevated temperatures to a favorable change in entropy of activation with an increase in chelate ring size. The Pt II catalyst precursor [(dpm)Pt(Ph)(THF)][BAr′4] is among the most active catalysts for ethylene hydrophenylation by a non-acid-catalyzed mechanism.
- McKeown, Bradley A.,Gonzalez, Hector Emanuel,Gunnoe, T. Brent,Cundari, Thomas R.,Sabat, Michal
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p. 1165 - 1171
(2013/07/26)
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- Control of olefin hydroarylation catalysis via a sterically and electronically flexible platinum(II) catalyst scaffold
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PtII complexes supported by dipyridyl ligands have been demonstrated to catalyze olefin hydroarylation. Herein, studies on the influence of dipyridyl motif variation are reported. Increasing the chelate ring size of dipyridyl-ligated PtII complexes from five- to six-membered rings by replacing 4,4′-di-tert-butyl-2,2′-bipyridine with 2,2′-dipyridylmethane has been shown to increase catalytic activity and longevity for catalytic ethylene hydrophenylation. For 2,2′-dipyridyl ligands, the presence of methyl groups in the 6/6′-positions of the pyridyl rings reduces the extent of dialkylation to produce diethylbenzenes but also increases the rate of catalyst decomposition. Substituting the methylene spacer between the pyridyl rings of 2,2′-dipyridylmethane with more electron-withdrawing groups also reduces catalytic efficiency. The steric profile of PtII complexes with increased chelate ring size or substituents in the 6/6′-positions of the pyridyl rings provides a marked change in regioselectivity for ethylene hydroarylation using ethylbenzene as well as the linear to branched selectivity for the hydrophenylation of propylene.
- McKeown, Bradley A.,Gonzalez, Hector Emanuel,Michaelos, Thoe,Gunnoe, T. Brent,Cundari, Thomas R.,Crabtree, Robert H.,Sabat, Michal
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p. 3903 - 3913
(2013/08/23)
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- Vapour phase ethylation of benzene over ZSM-5 synthesized in fluoride medium
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ZSM-5 zeolite (Si/Al ratio 50, 75 and 100) was hydrothermally synthesized in fluoride medium. Their crystal size and crystallinity were high. SEM images of synthesized material showed large elongated prismatic crystals. Their catalytic activity was examin
- Hariharan,Palanichamy,Murugesan
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p. 2679 - 2682
(2013/04/24)
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- Regioselective synthesis of alkylarenes by two-step ipso-substitution of aromatic dicarboxylic acids
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A strategy for the regioselective alkylation of arenes was developed, starting from commercially available and inexpensive terephthalic acid or naphthalene-1,4-dicarboxylic acid. The method entails a formal ipso-substitution of the carboxylate groups by a sequence of reductive alkylation under Birch conditions and subsequent acid-mediated rearomatization with loss of carbon monoxide and carbon dioxide. More than 20 different arenes with various side-chains were synthesized. With naphthalene-1,4-dicarboxylic acid as starting material, we were able to control the degree of alkylation by choosing the appropriate electrophile in the Birch reduction. Thus, bisalkylated naphthalenes and naphthoic acids became available chemoselectively. All reactions afforded a single regioisomer exclusively in high yields. Overall, aromatic dicarboxylic acids are suitable substrates for a two-step ipso-substitution that allows the selective synthesis of alkylated benzenes and naphthalenes.
- Bramborg, Andrea,Linker, Torsten
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p. 5552 - 5563
(2012/11/07)
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- InBr3-catalyzed reduction of ketones with a hydrosilane: Deoxygenation of aromatic ketones and selective synthesis of secondary alcohols and symmetrical ethers from aliphatic ketones
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An InBr3-Et3SiH reducing system was developed to selectively convert aliphatic ketones to a variety of secondary alcohols in moderate to good yields. An initial mixing of InBr3 and PhSiH 3 was followed by the addition of aliphatic ketones and a solvent to afford the symmetrical ether derivatives.
- Sakai, Norio,Nagasawa, Ken,Ikeda, Reiko,Nakaike, Yumi,Konakahara, Takeo
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experimental part
p. 3133 - 3136
(2011/06/26)
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- Mechanistic studies of ethylene hydrophenylation catalyzed by bipyridyl Pt(II) complexes
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Cationic platinum(II) complexes [(tbpy)Pt(Ph)(L)]+ [tbpy =4,4′-di-tert-butyl-2,2′-bipyridyl; L = THF, NC5F5, or NCMe] catalyze the hydrophenylation of ethylene to generate ethylbenzene and isomers of
- McKeown, Bradley A.,Gonzalez, Hector Emanuel,Friedfeld, Max R.,Gunnoe, T. Brent,Cundari, Thomas R.,Sabat, Michal
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experimental part
p. 19131 - 19152
(2012/01/12)
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- Selective synthesis of 1,4-dialkylbenzenes from terephthalic acid
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Terephthalic acid reacts with alkyl halides under Birch conditions to substituted 1,4-cyclohexadienes in high yields and good stereoselectivities. Electrophiles containing ester or nitrile groups undergo a surprising fragmentation under the reaction conditions. Subsequent treatment with chlorosulfonic acid proceeds by an interesting tandem decarbonylationldecarboxylation, affording 1,4-dialkylbenzenes in excellent regioselectivity. Thus our new method is superior to classical Friedel-Crafts alkylations.
- Bramborg, Andrea,Linker, Torsten
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supporting information; experimental part
p. 2195 - 2199
(2010/11/04)
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- Method for Producing Paraxylene Comprising an Adsortion Step and Two Isomerization Steps
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A process for producing para-xylene from a hydrocarbon feed is described in which an adsorption column operating as a simulated moving bed with at least five zones delivers an extract, a 2-raffinate and an intermediate raffinate. The extract is distilled and the distillate is optionally re-crystallized to recover para-xylene with a purity of at least 99.7%. The 2-raffmate is distilled then isomerized in a reactor preferably operating in the liquid phase and at a low temperature. The intermediate raffinate with an enriched ethylbenzene content is distilled then isomerized in the vapour phase.
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Page/Page column 5-6
(2008/12/04)
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- Process for the production of para-diethylbenzene
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The present invention relates to a process for the selective production of para-diethyl benzene from a mixed aromatic feedstock containing ethyl benzene and at least one other aromatic compound selected from benzene, alkylated benzene having alkyl group with carbon number 1 to 6, mono-alkyl aromatics, dialkyl aromatics, trialkyl aromatics, tetraalkyl aromatics, pentaalkyl aromatics, hexaalkyl aromatics, containing side chains having 1 to 6 carbon atoms, and any mixtures thereof the process comprising of (a) alkylating the feedstock under alkylating conditions, over a selectivated metallosilicate composite catalyst; and (b) recovering a product stream containing at least 95 wt % paradiethyl benzene, the product stream being substantially free from other isomers of diethylbenzene, Ca aromatics, C9 aromatics, C10+ heavy aromatics other than diethyl beizene isomers, sulphur, halogen, olefinc compound and carbonyl compounds.
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Page/Page column 10
(2008/06/13)
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- Practical synthesis of optically active fluorine-substituted α-phenylethylamines by retardation of hydrogenolytic cleavage at benzylic position
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High regioselectivity in hydrogenolysis of bis(α-methylbenzyl)amines having a fluorine atom on aromatic ring results from retardation of hydrogenolytic cleavage at benzylic position of fluorine-substituted aromatic ring.
- Kanai, Masatomi,Yasumoto, Manabu,Kuriyama, Yokusu,Inomiya, Kenjin,Katsuhara, Yutaka,Higashiyama, Kimio,Ishii, Akihiro
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p. 1424 - 1425
(2007/10/03)
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- Catalytic ring-attachment isomerization and dealkylation of diethylbenzenes over halide clusters of group 5 and group 6 transition metals
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A molybdenum halide cluster, (H3O)2[(Mo 6Cl8)Cl6]·6H2O, possessing an octahedral metal framework was used as a catalyst in a gas flow reactor under 1 atm of hydrogen. On reaction of p-diethylbenzene, dehydrogenation to ethylstyrene proceeded selectively at 300°C. At 400°C, mutual interconversion of o-, m-, and p-diethylbenzenes proceeded selectively. The ethyl group migrated by an intramolecular 1,2-shift mechanism without yielding disproportionation products. Niobium and tungsten chloride clusters with the same metal framework were also active catalysts for the isomerization of p-diethylbenzene. All the reactions resulted in appreciable yields of dealkylation products. The catalytic activity for isomerization can be ascribed to acid sites on the cluster surface, and the catalytic activity for dealkylation, to the metallic nature of the framework metal.
- Kamiguchi, Satoshi,Kondo, Kunihiko,Kodomari, Mitsuo,Chihara, Teiji
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- Ethylation of ethylbenzene over AFI type molecular sieves
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Magnesium, manganese and zinc incorporated aluminophosphate molecular sieves, MgMnAPO-5 and MnZnAPO-5, have been prepared by hydrothermal methods. The samples have been characterised by the techniques of XRD, FT-IR, 31P and 27Al MAS-NMR spectroscopy, BET-surface area, n-butylamine-TPD and ICP-MS. The cataiytic performance of these materials has been examined for ethylation of ethylbenzene with ethanoi in the vapour phase. MnZnAPO-5 has been found to be more active than MgMnAPO-5. The products are PDEB (1,4-diethylbenzene), MDEB (1,3-diethylbenzene), ODEB (1,2-diethylbenzene), PAB [(1,2,4 and 1,3,5-triethylbenzene) and (1,2,4,5-tetraethylbenzene)]. Maximum conversion (20.1%) has been noted at 350°C over MnZnAPO-5.
- Raj, K. Joseph Antony,Vijayaraghavan
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p. 254 - 257
(2007/10/03)
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- Process for alkylating aromatics
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A process for alkylating aromatics is provided which comprises contacting an aromatic-containing feed with alkylating agent in the presence of a silica-bound ZSM-5 zeolite catalyst, wherein the ZSM-5 has a crystal size no greater than 0.05 micron, said contacting being conducted under alkylating conditions to provide a product containing a monoalkylated aromatic fraction and a polyalkylated aromatic fraction, wherein the polyalkylated aromatic fraction contains at least 40 wt. % of the para-dialkylaromatic species. The polyalkylated aromatic fraction may be contacted with unsubstituted aromatic and a transalkylation catalyst under transalkylating conditions to provide a mono-alkylated aromatic-rich stream, e.g., an ethylbenzene-rich stream.
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Page column 8,9
(2008/06/13)
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- Kinetics and Mechanisms of Transalkylation and Disproportionation of meta-Diethylbenzene by Triflic Acid Catalyst
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The kinetics of transalkylation and isomerization of meta-diethylbenzene in the presence of benzene using triflic acid as a catalyst has been investigated. High catalytic activity of the triflic acid catalyst was observed in homogeneous liquid-phase reactions. On the basis of the product distribution obtained, transalkylation, disproportionation, and isomerization reactions have been considered and the main product of the reaction was ethylbenzene. These reactions are conducted in a closed liquid batch reactor with continuous stirring under dry nitrogen and atmospheric pressure over the temperature range of 288-308 K. The main transalkylation, disproportionation, and isomerization reactions occurred simultaneously and were considered as elementary reactions. The apparent activation energy of the transalkylation reaction was found to be 35.5 kj/mol, while that of disproportionation reaction was 42.3 kj/mol. The reproducibility of the experimental product distribution occurred with an average relative error of ±2%.
- Al-Zahrani,Al-Kinany,Al-Humaizi,Al-Khowaiter
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p. 555 - 563
(2007/10/03)
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- Para-selective ethylation of t-butylbenzene with diethyl carbonate over mesoporous molecular sieves
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The vapour phase ethylation of t-butylbenzene (t-BB) with diethyl carbonate has been studied over mesoporous Al-MCM-41 (Si/Al = 50 and 90) and Al, Mg-MCM-41 [Si/(Al+Mg) = 50] from 200 to 400°C. The products are benzene, ethylbenzene (EB), p-diethylbenzene (p-DEB), p-t-butylethylbenzene (p-tBEB) and p-t-butylvinylbenzene (p-tBVB). t-Butylbenzene conversion increases with increase in temperature up to 300°C, but above this temperature it decreases. Ortho and meta-products are completely absent. Ethylbenzene is the product of ethylation of benzene and cracking of p-tBEB.The selectivity of para-t-butylated products is favoured at lower temperature while higher temperature favours ethylbenzene selectivity. The influence of time on stream is examined over Al-MCM-41 (50) and the results are discussed in this paper.
- Umamaheswari,Palanichamy,Arabindoo, Banumathi,Murugesan
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p. 259 - 265
(2007/10/03)
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- Chemoselective control of hydrogenation among aromatic carbonyl and benzyl alcohol derivatives using Pd/C(en) catalyst
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The hydrogenolysis of aromatic ketones and aldehydes quite smoothly give the corresponding methylene compounds via the formation of the intermediary benzyl alcohols in the presence of Pd/C as a catalyst. Therefore, it is extremely difficult to isolate the intermediary benzyl alcohol selectively. This paper describes a mild and chemoselective hydrogenation method of an aromatic carbonyl compound to benzyl alcohol using the 10% Pd/C(en) catalyst and its application to the chemoselective deacetoxylation reaction at the benzylic position in the presence of the benzyl alcohol functionality within the molecule.
- Hattori, Kazuyuki,Sajiki, Hironao,Hirota, Kosaku
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p. 4817 - 4824
(2007/10/03)
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- Phenylene ethynylene diazonium salts as potential self-assembling molecular devices
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(matrix presented) Functionalized diazonium salts for molecular electronic devices are prepared by the reaction of the corresponding anilines with NOBF4 in sulfolane-acetonitrile solvent.
- Kosynkin, Dmitry V.,Tour, James M.
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p. 993 - 995
(2007/10/03)
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- Molecular engineering. Part 5.1 Tuning the constrictive binding of container host by the atomic order of portal pillars
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Two D4h container hosts 12 and 13 with 4(CH2-O-bridge-O-CH2) portal pillars were obtained in good yields by stepwise synthetic routes and showed complementary complexation behaviors to their analogues with (O-CH2-bridge-CH2-O)4 portal pillars. 1H NMR spectral chemical shifts of host's inward-turned OCH2O protons were sensitive to guest change. The stability orders of hemicarceplexes were 12-p-(CH3CH2)2C6H4 > 12-p-(CH3O)2C6-H4 ? 12-o-(CH3O)2C6H4 > 12-m-(CH3O)2C6H4 and 13-CH3COCH2CH3 > 13-CH3COCH2CH(CH3)2 > 13-CH3-CON(CH3)2 > 13-CH3COOCH2CH3 > 13-CH3CH2CON(CH3)2 in terms of the activation energy barrier for decomplexation. Large solvent effects on the activation energy for decomplexation of hemicarceplexes were observed.
- Ihm, Chaesang,Kim, Minkyu,Ihm, Hyejae,Paek, Kyungsoo
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p. 1569 - 1575
(2007/10/03)
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- Correlation between the catalytic activity of pentasils in alkylation of ethylbenzene by aqueous solutions of ethanol and ammonia TPD spectra
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The method of regional analysis of reaction rates was used to establish the correlation between the acidic properties of modified pentasil catalysts and their catalytic activity in the reaction of alkylation of ethylbenzene by ethanol and to determine the acidity range with the highest catalytic activity. The p- and m-isomers were found to be formed on sites having different acidities.
- Yushchenko,Romanovskii
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p. 557 - 562
(2007/10/03)
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- Reductive lithiation of arylalkyl methyl ethers
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We have investigated the reductive cleavage of arylalkyl methyl ethers with an excess of lithium metal and a catalytic amount of naphthalene. The reaction proceeds regioselectively in the presence of various substituents on the aromatic ring, allowing access to a wide array of arylalkyl lithium derivatives some of which are not easily accessible by conventional methods.
- Azzena, Ugo,Carta, Simonetta,Melloni, Giovanni,Sechi, Alessandra
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p. 16205 - 16212
(2007/10/03)
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- Concerted and Nonconcerted Reaction Path; Thermolysis of Dispirodeca-4,9-diene
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The enthalpy profile for the equilibrium 1 ->//-1).The observation of a nonconcerted path for the equilibrium 1 ->/- 3 is important with respect to the understanding of the controlling factor of the concerted and nonconcerted path of a reaction.The existence of a favourable potential energy path obviously is not of prime importance. - Keywords: Diradicals / Oxygen trapping / Energy well / Supercritic fluid reactions
- Roth, Wolfgang R.,Unger, Christian
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p. 1361 - 1366
(2007/10/02)
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- DETERMINATION OF COMPOSITION OF REACTION MIXTURES FROM ALKYLATION OF TOLUENE ON PHOSPHORUS-MODIFIED H-ZSM-5 ZEOLITE
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Determination of analytical composition of reaction mixtures formed by alkylation of toluene with ethylene on a phosphorus-modified H-ZSM-5 zeolite was made by capillary high resolution gas chromatography.Identification of individual components on these reaction mixtures was performed by GC-MS method, using the samples obtained at 320 and 400 deg C on H-ZSM-5 catalyst (modul 43.6) modified with 3.4 wt.percent phosphorus at toluene to ethylene molar ratio 4.5:1 and the catalyst loading expressed as weight hour space velocity WHSV (for toluene) = 6.9 h-1.The reaction mixtures contained a total 86 hydrocarbons.It was confirmed that in addition to the main alkylation reaction, there proceeds also ethylene oligomerization with subsequent cyclization and aromatization, disproportionation, alkylation and cyclization reactions of alkylaromatic hydrocarbons to give alkylnaphthalines and alkylindanes.
- Mravec, Dusan,Herain, Jiri,Holotik, Stefan
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p. 1832 - 1839
(2007/10/02)
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- Shape effects in the conversion of ethanol to hydrocarbons over alkaline-free synthesised ZSM-5 and aluminated silicalite-1 crystals
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Diffusion effects on conversion rates and product distributions in the ethanol to gasoline reaction on zeolite H-ZSM-5 were investigated.A sample of large ZSM-5 crystals (Si/Al 47) having a narrow particle-size distribution was hydrothermally synthesised
- Voogd, P.,Sollie, J. C.,Doelwijt, A.,Bekkum, H. van
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- Hydrogenolysis of Small Cycloalkanes, XV. - Hydrogenation of Dispirodeca-4,9-diene
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On hydrogenation of the title compound 1 with Pd/C 1,4-diethylbenzene (2) is formed in 95percent yield, furthermore 1percent of cis- and 2percent of trans-1,4-diethylcyclohexane (3 and 4) as well as 2percent of 6-ethylspirooctane (15) are found.With Pt/C the intermediates 7, 12, 13, and 14 and up to 45percent of dispirodecane (17) are identified. 17 is hydrogenated with PtO2 in acetic acid to form 1,1,4,4-tetramethylcyclohexane (19).
- Kiwus, Regina,Schwarz, Wolfgang,Rossnagel, Ingrid,Musso, Hans
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p. 435 - 438
(2007/10/02)
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