- Preparation of an MCM-41/nafionρ composite material; a selective catalyst for α-methylstyrene dimerization
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A MCM-41/Nafion composite prepared from tetraethoxysilane and Nafion gel solution with cetyltrimethylammonium surfactant, is a highly selective catalyst for α-methylstyrene dimerization to form the corresponding acyclic dimer.
- Fujiwara,Kuraoka,Yazawa,Xu,Tanaka,Souma
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Read Online
- Synthesis and Structure of a New Stable Carbocation Stabilized by Two Neighboring Sulfur Atoms. Dimethyl-9,9-bis(methylthio)-1-fluorenylcarbenium Ion
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9,9-Bis(methylthio)-1-isopropenylfluorene (3) and the corresponding alcohol 2 generate a carbocation 1 in trifluoroacetic acid solution at room temperature.This ion is sufficiently stable to be observed spectroscopically in this solution.A stable crystalline hexachloroantimonate of 1 was isolated.In trifluoroacetic acid-d at room temperature, the two C+-methyl groups of 1 undergo H-D isotopic exchange to give the corresponding hexadeuterio cation.On the basis of electronic and 1H NMR spectroscopic data at temperatures from 40 to -60 deg C, it is concluded that ion 1 is not a sulfonium species but exists as a carbocation stabilized by electrons from the two neighboring sulfur atoms.Carbon-13 NMR data show that the positive charge is extensively delocalized over the neighboring sulfur atoms, with small amount remaining on the carbon atom.The possibility is suggested that 1 is a pentacoordinated carbon species that resembles the transition states in SN2 displacements.
- Hojo, Masaru,Ichi, Tadaaki,Shibato, Kishio
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Read Online
- A chemoselective route to either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane from 2-phenylpropan-2-ol mediated by BiBr 3: A mechanistic study
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The reaction of 2-phenylpropan-2-ol mediated by BiBr3 can, through control of the temperature, yield selectively either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane. A reaction mechanism that proceeds via 1-methylstyrene is disclosed.
- Howard, Fredrick,Sawadjoon, Supaporn,Samec, Joseph S.M.
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Read Online
- Selective dimerization of a-methylstyrene by tunable bis(catecholato)germane Lewis acid catalysts
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The synthesis of a variety of bis(catecholato)germanes is reported. The Lewis acidity of the bis(catecholato)germanes was assessed using the experimental Gutmann-Beckett method and computational FIA and GEI methods. The oligomerization of alkenes using bis(catecholato)germanes demonstrates the use of these complexes in catalysis. The use of donor additives in the dimerization of a-methylstyrene resulted in selectivity control comparable to transition metal catalyst systems. This journal is
- Baines, Kim M.,Boyle, Paul D.,Cosby, Taylor P. L.,Henry, Andrew T.
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supporting information
p. 15906 - 15913
(2021/12/02)
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- Preparation of a platinum nanoparticle catalyst located near photocatalyst titanium oxide and its catalytic activity to convert benzyl alcohols to the corresponding ethers
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A novel platinum nanoparticle catalyst closely located near the surface of titanium oxide, PtNP/TiO2, has been prepared. This catalyst has both the properties of a photocatalyst and a metal nanoparticle catalyst, and acquired environmentally friendly catalytic activity, which cannot be achieved by just one of these catalysts, to afford ethers from benzyl alcohols under the wavelength of 420 nm.
- Akiyama, Toshiki,Arisawa, Mitsuiro,Harada, Kazuo,Honma, Tetsuo,Naka, Hiroshi,Saito, Susumu,Wada, Yuki
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p. 22230 - 22237
(2021/07/02)
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- Samarium triflate-catalyzed dimerization of vinylarenes
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We report the preparation of substituted indanes and their dimeric isomers via the samarium triflate-mediated [Sm(OTf)3, 10 mol%] self-dimerization of vinylarenes in MeNO2 at 25 oC for 10 h. The diverse products were obtained in moderate to high yields. The synthesis involves a (3+2) annulation via the formation of carbon-carbon bonds. Plausible mechanisms are proposed and discussed. The investigation of various rare metal triflates catalyst loadings, reaction conditions, and substrate scope led to an operationally easy one-pot Friedel-Crafts reaction protocol.
- Chang, Meng-Yang,Tsai, Yu-Lin
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p. 200 - 211
(2020/02/13)
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- Aerobic Oxidation of Secondary Alcohols with Nitric Acid and Iron(III) Chloride as Catalysts in Fluorinated Alcohol
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Fluorinated alcohols as solvents strongly influence and direct chemical reaction through donation of strong hydrogen bonds while being weak acceptors. We used 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the activating solvent for a nitric acid and FeCl3-catalyzed aerobic oxidation of secondary alcohols to ketones. Reaction proceeded selectively with excellent yields with no reaction on the primary alcohol group. Oxidation of benzyl alcohols proceeds selectively to aldehydes with only HNO3 as the catalyst, while reaction on tertiary alcohols proceeds through dehydration and dimerization. A mechanistic study showed in situ formation of NOCl that converts alcohol into alkyl nitrite, which in the presence of Fe3+ ions and fluorinated alcohol decomposes into ketone. The study indicates that iron(III) acts also as the single-electron transfer catalyst in regeneration of NOCl reactive species.
- Mo?ina, ?tefan,Iskra, Jernej
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p. 14579 - 14586
(2019/11/14)
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- Lewis Acid Catalyzed Transfer Hydromethallylation for the Construction of Quaternary Carbon Centers
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The design and gram-scale synthesis of a cyclohexa-1,4-diene-based surrogate of isobutene gas is reported. Using the highly electron-deficient Lewis acid B(C6F5)3, application of this surrogate in the hydromethallylation of electron-rich styrene derivatives provided sterically congested quaternary carbon centers. The reaction proceeds by C(sp3)?C(sp3) bond formation at a tertiary carbenium ion that is generated by alkene protonation. The possibility of two concurrent mechanisms is proposed on the basis of mechanistic experiments using a deuterated surrogate.
- Walker, Johannes C. L.,Oestreich, Martin
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supporting information
p. 15386 - 15389
(2019/10/28)
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- Decarbonylation of phenylacetic acids by high valent transition metal halides
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Triphenylacetic acid underwent unusual decarbonylation when allowed to react with a series of halides of group 4-6 metals in their highest oxidation state, in dichloromethane at ambient temperature. Thus, the reaction of CPh3COOH with MoCl5, in 1:1 molar ratio, afforded the trityl salt [CPh3][MoOCl4], 1, in 79% yield, while the 1:2 reaction of CPh3COOH with NbF5 afforded [CPh3][NbF6], 2, in 70% yield, NbOF3 being the metal co-product. CPh3COOH reacted with NbCl5, TiF4 and WOCl4 to give mixtures of compounds, however the cation [CPh3]+ was NMR identified in each case. [CPh3][NbCl6], 3, was isolated from NbCl5 and CPh3COCl, prior to being generated from CPh3COOH and PCl5. The reaction of CPh3COOH with TiCl4 was non-selective, and the salt [CPh3][Ti2Cl8(μ-κ2-O2CCPh3)], 4, was obtained in 18% yield. The decarbonylation reactions of CMePh2COCl and CMe2PhCOCl by means of NbCl5 led to the indanes 5a-b, which were isolated in 79-97% yields after hydrolysis of the mixtures and subsequent alumina filtration of the organic phases. The reactions of CH(Ph)2COOH with NbCl5 and WCl6 afforded NbCl4(OOCCHPh2), 6, and CHPh2COCl, respectively, as the prevalent species. CPh2(CH2CH2Br)COOH did not undergo CO release when allowed to interact with WCl6, instead selective intramolecular condensation to C(Ph)2C(O)OCH2CH2, 7, occurred. MeCCCOOH underwent hydrochlorination by WCl6 to give MeC(Cl)CHCOOH, 8, in 72% yield. All the products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. In addition, the solid state structures of 1, 2, 4, 7, and 8 were elucidated by X-ray diffraction.
- Bartalucci, Niccolò,Marchetti, Fabio,Zacchini, Stefano,Pampaloni, Guido
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p. 5725 - 5734
(2019/05/10)
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- Synthesis of 2-Substituted Propenes by Bidentate Phosphine-Assisted Methylenation of Acyl Fluorides and Acyl Chlorides with AlMe3
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Bidentate phosphine-assisted methylenation of acyl fluorides and acyl chlorides with substituted with aryl, alkenyl, and alkyl groups trimethylaluminum afforded an array of 2-substituted propene derivatives. The addition of a catalytic amount of DPPM increased an efficiency of the reactions. Trimethylaluminum as the methylenation reagent not only eliminates the presynthesis of methylene transfer reagent, but provides an efficient method for the synthesis of a series of 2-substituted propenes.
- Wang, Xiu,Wang, Zhenhua,Asanuma, Yuya,Nishihara, Yasushi
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supporting information
p. 3640 - 3643
(2019/05/17)
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- Straightforward formation of carbocations from tertiary carboxylic acids: Via CO release at room temperature
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We report an unprecedented mode of reactivity of carboxylic acids. A series of tertiary carboxylic acids, containing at least one phenyl α-substituent, undergo loss of carbon monoxide at room temperature (295 K), by a one pot reaction with 0.5-1 molar equivalents of WCl6 in dichloromethane. A plausible mechanism for the Ph3CCO2H/WCl6 reaction, leading to [CPh3][WOCl5] and Ph3CCl, is proposed on the basis of DFT calculations. The analogous reactions involving CEt(Ph)2CO2H, CMe(Ph)2CO2H and CMe2(Ph)CO2H selectively afforded stable hydrocarbons (alkene or indene, depending on the case), apparently resulting from the rearrangement of elusive tertiary carbocations.
- Bartalucci, Niccolò,Pampaloni, Guido,Marchetti, Fabio,Bortoluzzi, Marco,Zacchini, Stefano
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supporting information
p. 1574 - 1577
(2019/04/02)
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- Selective reaction of benzyl alcohols with HI gas: Iodination, reduction, and indane ring formations
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Reactions of benzyl alcohols with HI in solvent-free conditions were examined. Three types of reactions (iodination, reduction, and ring formation) occurred depending on the degree of crowding around the benzyl position and the benzylic stabilization of substrates. Results also showed that the ring formation to give indanes proceeded efficiently when HI was used, and that compounds with electron-rich aromatic rings gave indane derivatives in good yields.
- Matsumoto, Shoji,Naito, Masafumi,Oseki, Takehisa,Akazome, Motohiro,Otani, Yasuhiko
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p. 7254 - 7259
(2017/11/24)
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- METHOD FOR MANUFACTURING α-METHYLSTYRENATED PHENOL
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According to an embodiment of the present invention, the present invention provides a method for manufacturing α-methyl styrenated phenol, which comprises the following steps: (a) making phenol react with α-methyl styrene (AMS) under the presence of a first acidic catalyst to obtain a first product; and (b) additionally making 1-5 equivalents of α-methyl styrene for 1 equivalent of phenol react with the first product under the presence of a second acidic catalyst to obtain a second product. The manufactured α-methyl styrenated phenol does not generate environmental damage and is economical.(a) Making phenol react with α-methyl styrene (AMS) under the presence of a first acidic catalyst(AA) Obtaining 30-50 wt% of TMPI, 1-10 wt% DMP, 5-20 wt% of cumyl phenol, 1-10 wt% of AMS trimer, and the remaining phenol(b) Additionally making the α-methyl styrene react with a first product under the presence of a second acidic catalyst(BB) Obtaining 5-50 wt% of TMPI + DMP, 2-20 wt% of cumyl phenol, 1-10 wt% of dicumene, 20-60 wt% of dicumyl phenol, and 0.1-5 wt% of AMS trimerCOPYRIGHT KIPO 2017
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Paragraph 0035; 0036; 0067-0070; 0084
(2017/10/14)
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- Surface reactivity of non-hydrolytic silicophosphate xerogels: A simple method to create Br?nsted or Lewis acid sites on porous supports
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Non-hydrolytic sol-gel reactions of silicon acetates with trimethylsilyl (TMS) esters of phosphoric and phosphonic acids produce cross-linked matrices containing homogeneous dispersions of silicate and phosphoryl groups connected together by networks of Si-O-P(=O) linkages. The condensation degrees reach 80 to 90%. Residual organic groups (10 to 20%) were reacted with a variety of compounds (H2O, Me3SiOSiMe3, POCl3, SiCl4, AlMe3, Al(NMe2)3, and AlCl3) in order to enrich the surface of these porous matrices with Br?nsted (≡P-OH) and Lewis (tetracoordinated Al) acid functional groups. The differences in the reactivity of ≡Si-OAc and ≡P-OSiMe3 groups were utilized for the selective modification at the silicon and phosphorus atoms. The reaction procedures were optimized and significantly porous silicophosphate materials with a high content of either hydroxyl groups or four-coordinated aluminium species were obtained. The activity and selectivity of prepared samples as catalysts for the dimerization of α-methylstyrene were tested. Excellent activities and moderate to very high selectivities were achieved suggesting the potential use of silicophosphate xerogels in heterogeneous catalysis.
- Styskalik, Ales,Skoda, David,Moravec, Zdenek,Barnes, Craig E.,Pinkas, Jiri
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p. 3705 - 3715
(2016/05/09)
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- Metal-Free Domino One-Pot Decarboxylative Cyclization of Cinnamic Acid Esters: Synthesis of Functionalized Indanes
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Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid triggered decarboxylation of cinnamic acid esters and subsequent inter/intramolecular cyclization. Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter/intramolecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the aid of any metal salts.
- Gopi Krishna Reddy, Alavala,Satyanarayana, Gedu
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p. 12212 - 12222
(2016/12/23)
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- Iodine-Promoted Metal-Free Head-to-Tail Dimerization of Styrenes Affording 1,3-Diarylbut-1-enes
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A convenient and efficient iodine-mediated head-to-tail dimerization of styrenes to produce the corresponding dimers in the presence of triethyl phosphite is reported. The advantages of the present protocol are metal-free conditions, short reaction time, simplicity, and high efficiency.
- Wang, Dingyi,Fang, Yanjiao,Xie, Qihuang,Yan, Zhaohua,Lin, Sen,Guo, Shengmei
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supporting information
p. 2815 - 2818
(2016/12/16)
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- 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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- DICARBOXYLIC ACID MONOMERS AND METHODS OF MAKING AND USING THE SAME
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Disclosed herein are phenylindane dicarboxylic acid (PIDA) monomers, polymer compositions comprising the PIDA monomers, and methods of preparing PIDA monomers. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.
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Paragraph 0294
(2015/12/07)
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- Photocatalytic degradation of ciprofloxacin by synthesized TiO2 nanoparticles on montmorillonite: Effect of operation parameters and artificial neural network modeling
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TiO2/MMT nanocomposite was synthesized and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray fluorescence (XRF) and Brunauer-Emmett-Teller (BET) techniques. The average size of TiO2 nanoparticles was decreased from 60-80 nm to 40-60 nm through the immobilization on MMT. The main influential factors such as the TiO2/MMT dose, ciprofloxacin (CIP) concentration, pH of the solution, UV light regions, reusability of the catalyst and electrical energy determination were studied. The addition of radical scavengers (e.g. chloride, iodide, sulfate and bicarbonate) and enhancers (e.g. hydrogen peroxide, potassium iodate and peroxydisulfate) on the degradation efficiency was studied. The predicted data from the designed artificial neural network model were found to be in a good agreement with the experimental data (R2 = 0.9864). The main intermediates of CIP degradation were determined by GC-Mass spectrometry.
- Hassani, Aydin,Khataee, Alireza,Karaca, Semra
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p. 149 - 161
(2015/09/15)
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- Gold-catalyzed hydroarylation of alkenes with dialkylanilines
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Anti-Bredt di(amino)carbene supported gold(I) chloride complexes are readily prepared in two steps from the corresponding isocyanide complexes. In the presence of KB(C6F5)4as chloride scavenger, they promote the unprecedented hydroarylation reaction of alkenes with N,N-dialkylanilines with high para-selectivity. The latter are challenging arenes for Friedel-Craft reactions, due to their high basicity.
- Hu, Xingbang,Martin, David,Melaimi, Mohand,Bertrand, Guy
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supporting information
p. 13594 - 13597
(2015/02/05)
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- Combinations of ethers and B(C6F5)3 function as hydrogenation catalysts
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It works ether way: Labile adducts of dialkyl ethers with the electrophilic borane B(C6F5)3 are shown to scramble HD to H2 and D2 and catalyze the hydrogenation of 1,1-diphenylethylene. Copyright
- Hounjet, Lindsay J.,Bannwarth, Christoph,Garon, Christian N.,Caputo, Christopher B.,Grimme, Stefan,Stephan, Douglas W.
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supporting information
p. 7492 - 7495
(2013/07/26)
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- A kinetic model of the dimerization of α-methylstyrene in the presence of high-silica zeolite y
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The kinetics of the dimerization of α-methylstyrene in the presence of high-silica zeolite HNaY has been studied, and a nine-stage scheme of the monomer conversion has been developed. Analysis of the kinetic models developed in the form of the Langmuir-Hinshelwood relationships and in terms of the mass action law has shown that the first model more adequately describes the experimental data. The numerical values of kinetic and adsorption parameters are represented. Pleiades Publishing, Ltd., 2012.
- Balaev,Grigor'Eva,Khazipova,Kutepov,Dzhemilev
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p. 426 - 431
(2013/01/16)
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- Highly efficient Pd(acac)2/TFA catalyzed head-to-tail dimerization of vinylarenes at room temperature
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Pd(acac)2 catalyzed dimerization of vinylarenes to form dimers under mild condition with excellent yields and stereoselectivities. In particular, the use of TFA highly promoted the activity and selectivity of the dimerization. The studies on mechanism for the reaction displayed clearly that the dimerization of styrenes is 100% atom economic reaction.
- Ma, Hengchang,Sun, Qiangsheng,Li, Wenfeng,Wang, Jinxia,Zhang, Zhe,Yang, Yaoxia,Lei, Ziqiang
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scheme or table
p. 1569 - 1573
(2011/05/05)
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- Remarkable effect of valence electrons in thiolato-bridged diruthenium complexes toward catalytic dimerization of α-methylstyrenes
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The dicationic diruthenium complex 1c (RuIII-RuIII) catalytically promotes the dimerization of α-methylstyrenes into the corresponding acyclic dimers, while the use of the mixed-valence diruthenium complex (RuIII-RuIV) generated from 1c and cinnamyl chloride as an active catalyst affords the corresponding indanes via cyclization of the acyclic dimers. The selectivity of the catalytic dimerization of α-methylstyrenes depends on the nature of electrophilicity due to valence electrons in the diruthenium cores between RuIII-RuIII and RuIII-RuIV.
- Miyake, Yoshihiro,Moriyama, Taichi,Tanabe, Yoshiaki,Onodera, Gen,Nishibayashi, Yoshiaki
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experimental part
p. 5972 - 5977
(2012/01/04)
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- High temperature vapor phase reactions of nitrogen trifluoride with benzylic substrates
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At temperatures around 400°C, nitrogen trifluoride (NF3) readily reacts with benzylic substrates. Products vary with the substrate, but are all the result of difluoroamination at the benzylic position. Toluene and ethylbenzene produce benzonitrile. Cumene produces α-methylstyrene. Diphenylmethane produces benzanilide. Little or no direct fluorination or radical dimerization is observed.
- Belter, Randolph K.
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scheme or table
p. 318 - 322
(2011/06/26)
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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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- Alkoxymagnesium iodide complexes
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The complexes R(Ph)MeCOMg(Et2O)I [1, R = Me (a), Ph (b)] were obtained by the reaction of R(Ph)C=O with MeMgI in diethyl ether in good yields. Crystallisation of 1 from acetonitrile resulted in single crystals of di- and trinuclear complexes I2(μ-OCPhMe2)2Mg(MeCN) 4 (2) and {2[I(MeCN)Mg(μ-OCPh2Me)2Mg(MeCN)I] (3) × [I(MeCN)Mg(μ-OCPh2Me)2Mg(μ-OCPh 2Me)2Mg(MeCN)I] (4) × 2CH2Cl2} in which the metal centres are linked by alkoxy substituents. The thermal decomposition of the complexes 1 was studied by successive detection of the EI mass spectra of diethyl ether, the olefins 5, the tertiary alcohols 6, and the formal olefin dimers 7. The complexes R1(Ph)MeCOMg(Et2O)I [1, R1 = Me (a), Ph (b)] are obtained by the reaction of R 1(Ph)C=O with MeMgI in diethyl ether in good yields. Crystallisation of 1 from acetonitrile results in single crystals of di- and trinuclear complexes (2, 3 and 4) in which the metal centres are linked by alkoxy substituents. The thermal decomposition of the complexes 1 is monitored by mass spectral detection of the decomposition products. Copyright
- Haiss, Peter,Kuhn, Annette,Kuhn, Norbert,Maichle-Moessmer, Caecilia,Laufer, Stefan,Steimann, Manfred,Zeller, Klaus-Peter
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p. 3284 - 3287
(2011/09/21)
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- Efficient double bond migration of allylbenzenes catalyzed by Pd(OAc) 2-HFIP system with unique substituent effect
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A novel catalyst system of Pd(OAc)2-HFIP induces double-bond migration of allylbenzenes under mild conditions with low catalytic loading to afford 1-propenylbenzenes. The reaction shows a unique substituent effect that is highly dependent on the distance of substituents from the allylic moiety. Thus, the reactivity of substrates bearing a methyl group is ordered in para > meta > ortho, whereas it is entirely reversed as ortho > meta > para for methoxy and chloro substituents.
- Nishiwaki, Nagatoshi,Kamimura, Ryuichiro,Shono, Kimihiro,Kawakami, Toshihiko,Nakayama, Katsuhisa,Nishino, Kohei,Nakayama, Takayuki,Takahashi, Keisuke,Nakamura, Aki,Hosokawa, Takahiro
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supporting information; scheme or table
p. 3590 - 3592
(2010/08/19)
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- Gold(I)-catalyzed intermolecular [2+2] cycloaddition of alkynes with alkenes
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The gold(I)-catalyzed intermolecular reaction of terminal alkynes with alkenes leads to cyclobutenes. The use of sterically hindered cationic Au(I) complexes as catalysts is key for the success of this reaction.
- Lopez-Carrillo, Veronica,Echavarren, Antonio M.
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supporting information; experimental part
p. 9292 - 9294
(2010/11/03)
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- Dimerization of α-methylstyrene in the presence of mordenite, aimed at preparation of transformer oils
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Dimerization of α-methylstyrene in the presence of natural mordenite and its modified form was studied. The dependence of the yield and composition of the products on the process parameters was found. Conditions were determined for preparing linear dimers with a high selectivity.
- Rustamov,Seidov,Ibragimov,Mamedbeili
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scheme or table
p. 317 - 322
(2009/06/06)
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- Cyclodimerization of α-methylstyrene under homogeneous and heterogeneous acid catalysis conditions
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The cyclodimerization of α-methylstyrene in the presence of Broensted and Lewis acids was realized. The dependence of the cyclic α-methylstyrene dimer yield on the catalyst nature and structure was established. It was shown that the activity of the catalysts is determined by the strength of their acid sites, and the selectivity for the cyclic α-methylstyrene dimer depends on the nature of the anion (homogeneous acids) or the porous structure (heterogeneous catalysts). Sulfuric acid and silicophosphate exhibit the highest selectivity in the cyclodimerization of α-methylstyrene into 1,1,3-trimethyl-3-phenylindane.
- Kirichenko,Grigor'Eva,Glazunova,Dzhemilev
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experimental part
p. 306 - 310
(2010/06/19)
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- Acid-promoted SN1/E1 fragmentation/dimerization of 2-cumylmalonates
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Several diethyl 2-cumylmalonates underwent fragmentation and dimerization in PPA at elevated temperatures to give 1,1,3-trimethyl-3-arylindanes in good yields. The same products were obtained from 2-cumylmalonic acid, ethyl 2-cumylcyanoacetate, and 2-cumy
- Reeves, Jonathan T.,Fandrick, Daniel R.,Tan, Zhulin,Song, Jinhua J.,Yee, Nathan K.,Senanayake, Chris H.
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scheme or table
p. 3077 - 3080
(2009/10/04)
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- Conversion of α-methylstyrene over pentasil zeolites with various silica ratios
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It has been shown that α-methylstyrene in the presence of H-HSZ (SiO2/Al2O3 = 40-120) and Fe-HSZ (SiO 2/Al2O3 = 60) pentasils in a nitrogen atmosphere (80-120°C, 5-20 wt % catalyst) is converted into linear (4-methyl-2,4-diphenylpent-1-and-2-enes) and cyclic (1,1,3-trimethyl-3- phenylindan) dimers. The H-type high-silica (SiO2/Al 2O3 = 120) and ferrosilicate zeolites in air facilitate the conversion of α-methylstyrene into acetophenone and α-phenylpropionaldehyde.
- Grigor'eva,Galyautdinova,Vosmerikov,Korobitsina,Kutepov,Dzhemilev
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scheme or table
p. 366 - 370
(2010/07/03)
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- Acid-catalyzed alkenylation of aromatic compounds with 1,3-pentadiene as a route to new modifying additives for polymer compounds
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Alkenylation of a series of aromatic compounds with 1,3-pentadiene was studied. The oligomeric alkenylation products cured with hexamethylenetetramine were used for modifying elastic-strength properties of elastomeric compounds and improving the compatibility of the elastomers with silicic acid fillers.
- Rossinskii,Alalykin,Talantov,Chagaev
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p. 1423 - 1426
(2008/12/23)
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- Switching catalytic reaction conducted in pore void of mesoporous material by redox gate control
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A molecular gate attached on the pore outlet of a mesoporous material, which is opened and closed by redox system of thiol groups, effectively switched the progress of a catalytic reaction promoted by the acidic site in the pore void. The Royal Society of Chemistry 2006.
- Fujiwara, Masahiro,Terashima, Shigeki,Endo, Yasuko,Shiokawa, Kumi,Ohue, Hiroyoshi
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p. 4635 - 4637
(2007/10/03)
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- Dimerization of α-methylstyrene on high-silica zeolites
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α-Methylstyrene dimerization was studied on high-silica β, ZSM-12, and TsVN zeolites. The acid properties of the zeolites were studied by IR spectroscopy. It was revealed that the catalytic properties of the zeolites in α-methylstyrene dimerization depend on both the acidic and structural characteristics of the catalysts. The highest activity in the reaction was exhibited by zeolite β, as the maximum amount of acid sites were found in its structural units (inside channels, on the outer surface). Zeolite ZSM-12 had the highest selectivity for linear dimers. Nauka/Interperiodica 2006.
- Grigor'eva,Galyautdinova,Paukshtis,Kutepov,Tselyutina,Dzhemilev
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p. 332 - 337
(2007/10/03)
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- Temperature-controlled highly selective dimerization of α-methylstyrene catalyzed by Br?nsted acidic ionic liquid under solvent-free conditions
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A temperature-controlled highly selective dimerization of α-methylstyrene to produce 2,4-diphenyl-4-methyl-1-pentene and 1,1,3-trimethyl-3-phenylindan was catalyzed by Bro?nsted acidic ionic liquid [Hmim]+BF4-. At 60 °C, 2,4-diphenyl-4-methyl-1-pentene was formed in 93% selectivity with >92% conversion under a solvent-free condition while 1,1,3-trimethyl-3-phenylindan could be obtained in 100% selectivity when the reaction temperature was increased to 170 °C. The ionic liquid [Hmim]+BF4- could be reused with almost no loss of activity.
- Wang, Haiming,Cui, Peng,Zou, Gang,Yang, Fan,Tang, Jie
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p. 3985 - 3988
(2007/10/03)
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- Iodine induced transformations of alcohols under solvent-free conditions
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Iodine has been shown to be an efficient catalyst for transformations of alcohols under solvent-free conditions. In the presence of 5% of iodine, tertiary alcohols underwent dehydration forming the corresponding alkenes, while in the case of 2-phenylpropane-2-ol cyclodimerisation to 1,1,3-trimethyl-3-phenylindane took place. Secondary and primary benzyl alcohols under the same conditions gave the corresponding ethers.
- Stavber, Gaj,Zupan, Marko,Stavber, Stojan
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p. 8463 - 8466
(2007/10/03)
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- An efficient and selective hydroarylation of styrenes with electron-rich arenes, catalyzed by bismuth(III) chloride and affording Markovnikov adducts
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In the presence of BiCl3, the hydroarylation of styrenes with electron-rich arenes afforded Markovnikov adducts selectively in good to high yields. Under arene-free conditions, the intermolecular hydroarylation of α-substituted styrenes and subsequent intramolecular hydroarylation produced the cyclic dimers of α-substituted styrenes in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Sun, Hong-Bin,Li, Biao,Hua, Ruimao,Yin, Gwu
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p. 4231 - 4236
(2007/10/03)
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- Evidence that SCS pincer Pd(II) complexes are only precatalysts in Heck catalysis and the implications for catalyst recovery and reuse
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SCS-pincer Pd(II) complexes have been covalently immobilized onto porous silica, cross-linked polymer (Merrifield resin) and soluble poly(norbornene) supports via either amide or urea linkages and evaluated in the Heck coupling of iodobenzene with n-butyl acrylate. Kinetic experiments and poisoning studies indicate that in all cases the pincer complexes merely act as precatalysts. Contrary to literature reports, there is no evidence for catalysis by the intact amide-linked SCS-Pd(II) complexes under any conditions studied here.
- Yu, Kunquan,Sommer, William,Richardson, John M.,Weck, Marcus,Jones, Christopher W.
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p. 161 - 171
(2007/10/03)
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- Assembly of heteropoly acid nanoparticles in SBA-15 and its performance as an acid catalyst
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Keggin-type 12-tungstophosphoric acid (TPA) nanocrystals have been assembled inside the pores of mesoporous silica through a vacuum impregnation method by using largepore SBA-15 as a nanoreactor. The product was characterized by Brunauer-Emmet-Teller particle size distri bution (BET-PSD), NMR and FT-IR spectroscopy, X-ray diffraction (XRD), tranmsission electron microscopy (TEM), differential thermal analysis (DTA) and FT-IR of adsorbed pyridine. The experimental results illustrale that the TPA nanocrystals are excellent Bronsted acid catalytic materials at room temperature.
- Yu, Shu-Yuan,Wang, Li-Ping,Chen, Bo,Gu, Ying-Ying,Li, Jing,Ding, Han-Ming,Shan, Yong-Kui
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p. 3894 - 3898
(2007/10/03)
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- A practical synthesis and estrogenic activity of 5-hydroxy-1-(4′- hydroxyphenyl)-1,3,3-trimethylindan, a contaminant in industrial grade bisphenol A
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A practical synthesis of 5-hydroxy-1-(4′-hydroxyphenyl)-1,3,3- trimethylindan was achieved from α-methylstyrene. The starting compound was dimerized in the presence of trifluoroacetic acid to produce 1-phenyl-1,3,3-trimethylindan. Aromatic nitration of the phenylindane was carried out using a mixture of nitric acid and acetic anhydride. The nitro group was then converted to hydroxyl via reduction and a diazonium salt sequence to form 5-hydroxy-1-(4′-hydroxyphenyl)-1,3,3-trimethylindan. The estrogenicity of the product was 8.7 times that of BPA. Our finding has demonstrated the endocrine-disrupting properties of the product. Copyright
- Terasaki, Masanori,Shiraishi, Fujio,Nishikawa, Tomohiro,Morita, Masatoshi,Makino, Masakazu
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p. 188 - 189
(2007/10/03)
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- Novel dimerization, alkoxylation, and sulfidation of olefins catalyzed by RuCl3·nH2O
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Novel ruthenium-catalyzed reactions that employ ruthenium trichloride n-hydrate (RuCl3·nH2O) were investigated and dimerization, alkoxylation and sulfidation of olefins were noted. Adducts of Markovnikov type and anti-Markovnikov type were obtained in a stereospecific manner and in good yield, depending on the type of olefins used as the starting materials. (Graph Presented).
- Higashimura, Mitsuteru,Imamura, Keita,Yokogawa, Yukiko,Sakakibara, Tsutomu
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p. 728 - 729
(2007/10/03)
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- Indium(III) bromide-catalyzed chemioselective dimerization of vinylarenes
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Indium(III) bromide catalyzes the dimerization of α-substituted vinylarenes. Chemioselectivity towards open chain or cyclic dimers depends on the nature of the substituent at the aryl group of the vinylarene.
- Peppe, Clovis,Lang, Ernesto Schulz,De Andrade, Fabiano Molinos,De Castro, Liérson Borges
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p. 1723 - 1726
(2007/10/03)
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- Isobutene Polymerization Using a Chelating Diborane Co-Initiator
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Lewis acidic diborane 1 (J. Am. Chem. Soc. 1999, 121, 3244?3245) is highly effective for both proton- and cationogen-initiated isobutene polymerization in hydrocarbon media at low temperature. Reactions of diborane 1 with cumyl chloride and cumyl methyl ether were studied by variable-temperature 1H and 19F NMR spectroscopy. At low temperatures stable ion pairs 2a and 2b are formed; at higher temperatures these ion-pairs form phenyl-1,3,3-trimethylindan (3) with concomitant release of HCl to form 1 in the case of 2a or degradation of the anion (2b). Reaction between Ph3C-Cl and diborane 1 resulted in the generation of an ion-pair 4 consisting of the Ph3C cation very weakly associated with the chelated, μ-Cl counteranion as revealed by X-ray crystallography. Copyright
- Lewis, Stewart P.,Taylor, Nicholas J.,Piers, Warren E.,Collins, Scott
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p. 14686 - 14687
(2007/10/03)
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- Oligomerization of α-methylstyrene in the presence of mordenite type zeolite
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The activity and selectivity of coarse-porous H-mordenite in synthesis of cyclic and linear dimers of α-methylstyrene were studied.
- Grigor'eva,Kutepov,Makhamatkhanov,Bikbaev,Khazipova,Kovtunenko
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p. 1539 - 1540
(2007/10/03)
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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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- Some procedures of oligomerization of α-methylstyrene
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The use of zeolites Y with various Broensted acidity and also methylene chloride as a solvent for production of α-methylstyrene dimer, used as a chain-terminating agent in polystyrene production, was studied.
- Talzi,Doronin,Sorokina,Ignashin
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p. 835 - 838
(2007/10/03)
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- Dimerization of β-methylstyrene in the presence of catalysts based on zeolite-like crystalline aluminophosphates
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Catalytic properties of the systems prepared from the crystalline aluminophosphate VPI-5, whose lattice included 18-membered rings of Al and P atoms with the free diameter of -12-13 A, and from its Si and Mn modifications (Si-VPI-5 and Mn-VPI-5) were examined in liquid-phase dimerization of α-methylstyrene. Rearrangement, though incomplete, of the VPI-5 structure into the AIPO4-8 structure with narrower 14-membered rings was found to occur upon thermal treatment of these materials before their using in catalysis. The conversion of the starting monomer reaches 97%, the yield of 2,4-diphenyl-4-methylpentene-1 and 2,4-diphenyl-4-methylpentene-2 is 94%, and the selectivity of formation of linear dimers is ~96% under mild conditions (p = 0.1 MPa and t = 75-100°C) on the catalyst formed from the unmodified crystallite. The amount of the cyclic dimer, 1,1,3-trimethyl-3-phenylindan and α-methylstyrene trimers in the catalyzate is no more than 3%. This permits the use of the obtained product for various purposes with no additional treatment. The catalysts SAPO4-8 and Mn-AlPO4-8 modified with Si and Mn, respectively, exhibit a higher activity in conversion of α-methylstyrene, but their selectivity for formation of linear α-methylstyrene dimers is much lower. For Mn-AlPO4-8, the yields of 1,1,3-trimethyl-3-phenylindan reach 45%, which is approximately half the total α-methylstyrene conversion. The possible nature of the active sites involved in the catalysis is discussed. Copyright
- Isakov,Minachev,Sharf,Litvin
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p. 251 - 256
(2007/10/03)
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- A liquid-liquid process for production of 2,4-diphenyl-4-methyl-1-pentene by dimerization of α-methylstyrene
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A liquid-liquid process for the dimerization of α-methylstyrene (AMS) in order to produce selectively the commercially useful 2,4-diphenyl-4-methyl-l-pentene has been developed. The aqueous phase contained sulfuric acid as a catalyst and methanol as an additive, and the organic phase was 97% α-methylstyrene (AMS). An AMS conversion of 55% was achieved in 7 h when the dimerization was conducted at 80 °C. The product dimer contained 93% 2,4-diphenyl-4-methyl-1-pentene and only 0.06% 1,1,3-triniethyl-3-phenylindan, the saturated dimer. The liquid-liquid process can be used commercially to produce selectively 2,4-diphenyl-4-methyl-1-pentene at locations where cation-exchange resins are not readily available.
- Chaudhuri, Basab
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p. 220 - 223
(2013/09/08)
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- Reaction of alcohols with camphene over β-zeolite
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Alkylation of fatty-aromatic alcohols with camphene over β-zeolite takes two pathways: O-alkylation which is preceded by isomerization of protonated camphene and addition at the camphene double bond of a carbocation formed by protonation and subsequent dehydration of the alcohol. As a result, products of aralkylation or cyclization are obtained, depending on the alcohol structure.
- Fomenko,Korchagina,Yarovaya,Gatilov,Salakhutdinov,Ione,Barkhash
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p. 1006 - 1017
(2007/10/03)
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