- An Eco-friendly Soft Template Synthesis of Mesostructured Silica-Carbon Nanocomposites for Acid Catalysis
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The synthesis of ordered mesoporous silica-carbon composites was explored by employing TEOS and sucrose as the silica and carbon precursor respectively, and the triblock copolymer F127 as a structure-directing agent via an evaporation-induced self-assembly (EISA) process. It is demonstrated that the synthesis procedures allow for control of the textural properties and final composition of these silica-carbon nanocomposites via adjustment of the effective SiO2/C weight ratio. Characterization by SAXS, N2 physisorption, HRTEM, TGA, and 13C and 29Si solid-state MAS NMR show a 2D hexagonal mesostructure with uniform large pore size ranging from 5.2 to 7.6 nm, comprising of separate carbon phases in a continuous silica phase. Ordered mesoporous silica and non-ordered porous carbon can be obtained by combustion of the pyrolyzed nanocomposites in air or etching with HF solution, respectively. Sulfonic acid groups can be readily introduced to such kind of silica-carbon nanocomposites by a standard sulfonation procedure with concentrated sulfuric acid. Excellent acid-catalytic activities and selectivities for the dimerization of styrene to produce 1,3-diphenyl-1-butene and dimerization of α-methylstyrene to unsaturated dimers were demonstrated with the sulfonated materials. Tintin and the sulfurous nanocatalysts: Sulfonic acid groups can be readily introduced to mesostructured silica-carbon nanocatalysts to reveal excellent acid-catalytic activities and selectivities for the dimerization of styrene to produce 1,3-diphenyl-1-butene and the dimerization of α-methylstyrene.
- Zhong, Ruyi,Peng, Li,De Clippel, Filip,Gommes, Cedric,Goderis, Bart,Ke, Xiaoxing,Van Tendeloo, Gustaaf,Jacobs, Pierre A.,Sels, Bert F.
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p. 3047 - 3058
(2015/09/22)
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- Synthesis of (E)-4-phenyl-3-buten-2-one by the reaction of styrene with acetic anhydride in the presence of zeolite catalysts
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The high catalytic activity and selectivity of zeolites HBeta and HZSM-12 were found in the synthesis of (E)-4-phenyl-3-buten-2-one by the reaction of styrene with acetic anhydride.
- Suleimanova,Grigor'Eva,Bubennov,Gizetdinova,Tselyutina,Kutepov
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p. 435 - 437
(2014/01/17)
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- Codimerisation of styrene and α-methylstyrene in the presence of zeolites
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The reaction of styrene with α-methylstyrene has been studied over Y, Beta and ZSM-12 zeolites at 80-120 °C in the presence or absence of chlorobenzene. Homo- and codimers of styrene and α-methylstyrene were the main reaction products. The yield of dimers
- Grigor'eva,Bubennov,Khalilov,Kutepov
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experimental part
p. 85 - 90
(2012/07/13)
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- Silica-supported heteropolyacids readily induce cyclodimerization of styrenes and stilbenes
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Heteropolyacids such as molybdophosphoric and tungstophosphoric acids, supported over silica, readily induce cyclodimerisation reactions of styrenes and stilbenes affording a mixture of indane and/or tetraline derivatives with remarkably high efficiency and in reduced reaction time.
- Alesso, Elba,Torviso, Rosario,Erlich, Magali,Finkielsztein, Liliana,Lantano, Beatriz,Moltrasio, Graciela,Aguirre, Jose,Vazquez, Patricia,Pizzio, Luis,Caceres, Carmen,Blanco, Mirta,Thomas, Horacio
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p. 3803 - 3812
(2007/10/03)
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- FTIR and reaction studies of styrene and toluene over silica-zirconia-supported heteropoly acid catalysts
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The interactions of styrene and toluene with a sol-gel-prepared SiO2-ZrO2 mixed oxide and with two supported heteropolytungstic acid samples, i.e., a Keggin type (H3PW12O40) and a Dawson type (H6PW18O62) were studied by FTIR. Both supported heteropoly acids (HPA) were highly active, leading to styrene conversions of ≤ 94% after 4 hr, while the pure SiO2-ZrO2 support was almost inactive, with only 8% conversion after the safe reaction time. The Dawson catalyst showed higher activity than the supported Keggin. The catalysts differed in activity and in the product distribution, as reflected in the levels of conversion after equivalent reaction times. Toluene adsorption on HPA(K)/SiZr and HPA(D)/SiZr gave similar spectra, as observed for adsorption on the support alone. Increased pressures of styrene progressively demonstrated the adsorbed toluene, resulting in a typical spectrum of polymeric species on the catalysts, with maxima at 1601, 1583, 1494, 1478, 1450, and 1378/cm. The presence of zirconium in SiO2-ZrO2 mixed oxides led to the generation of Bronsted acid sites, which were otherwise absent in the single-component oxides. HPA addition to the SiO2-ZrO2 support led to an increase in the number of sites, which were available for the activation and subsequent reactions involving styrene, as confirmed by the increase activity in catalytic tests in the FTIR study.
- Bachiller-Baeza,Anderson
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p. 231 - 239
(2007/10/03)
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- Hydride transfer reactions of benzylic alcohols catalyzed by acid faujasites
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Reaction of five benzylic alcohols in solution at 78 deg C has been performed in the presence of a series of HY zeolites at three different levels of Na+-to-NH4+ exchange (HY-21, HY-50 and HY-100) and framework Si-to-Al ratio (HY-100, HY-200 and HY-400).Dehydration to form a C=C double bond is the main primary process for 1-phenyl- and 1,1-diphenylethanol.Nevertheless, the initial alkenes are unstable, giving rise to the corresponding phenylethanes and, in the case of styrene, also to dimers.In contrast, benzyl alcohol and diphenylmethanol gave equimolar amounts of phenylmethanes and phenyl ketones, by an intermolecular hydride transfer not observed under conventional homogeneous acid catalysis.This process was found to be highly demanding from the point of view of the acid strength of the sites involved.Finally, triphenylmethanol showed a remarkable reluctance to undergo any change, although small amounts of triphenylmethane, benzophenone and 9-phenyl-9-hydroxyfluorene were detected after long reaction times.
- Climent, Maria J.,Corma, Avelino,Garcia, Hermenegildo,Iborra, Sara,Primo, Jaime
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p. 275 - 278
(2007/10/02)
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- ACID-CATALYZED DIMERIZATION AND ARALKYLATION IN DIVINYLAROMATIC COMPOUND-AROMATIC SOLVENT SYSTEMS
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On heating styrene and bis(4-vinylphenyl) ether or a linear unsaturated aromatic oligomer with terminal vinyl groups in aromatic solvents, depending on the temperature and concentration of toluene-p-sulfonic acid, there are obtained predominantly dimers and linear oligomers, and/or products of the alkylation of the aromatic solvent by the unsaturated monomers, dimers, and oligomers.
- Zaitsev, B. A.,Kiseleva, R. F.,Denisov, V. M.,Kol'tsov, A. I.
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p. 2323 - 2330
(2007/10/02)
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- PREPARATION OF SOME TRIMETHYL- AND METHYLETHYLBIPHENYLS AND REACTIVITY OF AROMATIC HYDROCARBONS IN THE GOMBERG REACTION
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Trimethyl- and methylethylbiphenyls with the alkyl groups in the both phenyl rings have been prepared by the Gomberg reaction and identified by the capillary gas-liquid chromatography.Depending on choice of the aromatic hydrocarbon either individual isomers or their mixtures (three at the most) have been obtained which were contaminated with compounds of diarylmethane type in many cases.The methylethylbiphenyls have only been prepared as mixtures contaminated with diarylmethanes.These side products have been prepared by independent syntheses.A method has been developed for isolation and separation of mixtures of trimethyl- and methylethylbiphenyls from the reaction products containing tarry products.The method is suitable for preparation of small amounts of some analytical standards.The HMO method has been used for calculation of values of the radical superdelocalizabilities at individual centres in the molecules of o-, m- and p-xylene, toluene and ethylbenzene, and these values have been compared with composition of the Gomberg reaction products from these hydrocarbons.The competitive technique has been used for comparison of the reactivities of the mentioned aromatic substrates in the Gomberg reactions.
- Novrocik, Jan,Novrocikova, Marta,Titz, Milos
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p. 3140 - 3149
(2007/10/02)
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- Manufacture of 1-methyl-3-(monohalogeno)-phenylindans and dihalogeno-1-methyl-3-phenylindans
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Manufacture of 1-alkyl-3-(monohalogeno)-phenylindans and dihalogeno-1-methyl-3-phenylindans by reaction of halogenostyrene and styrene in the presence of phosphoric acid of a certain concentration, or by reaction of halogenostyrenes in the presence of phosphoric acid of a certain concentration and of organic compounds irradiated with light of 2,000 to 8,000 A and capable of absorbing the said light, and the new dihalogeno-1-methyl-3-phenylindans and 1-methyl-3-(monohalogeno)-phenylindans. The products are starting materials for the manufacture of dyes and pesticides.
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