- Zr-catalyzed olefin alkylations and allylic substitution reactions with electrophiles
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Disubstituted aryl olefins undergo efficient alkylations in the presence of 5 mol % Cp2ZrCl2, n-BuMgCl, and alkyl tosylates or alkyl bromides. In one class of reactions (Table 1), the resulting alkyl zirconocene (initial alkylation product) undergoes β-hydride abstraction with a hydrogen atom from within the substrate to afford allylic alkylation products (Scheme 5). In another category of reactions, where cyclic allylic ethers (chromenes) are used (Table 2), Zr-alkoxide elimination occurs after the C-C bond formation to effect a net allylic substitution. It is proposed that these reactions involve the nucleophilic attack of substrate-derived zirconates or zirconocene-Grignard reagents on various tosylates and bromides. There is little or no competitive electrophile alkylation by the n-alkyl Grignard reagent. Several mechanistic and synthetic aspects of these Zr-catalyzed C-C bond forming reactions are examined and discussed.
- De Armas, Judith,Kolis, Stanley P.,Hoveyda, Amir H.
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- Hexadecane Conversion on an Alumina–Nickel Catalyst
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Abstract: The conversion of hexadecane on a 4% Ni/Al2O3 catalyst in a temperature range of 20–300°C was studied using IR spectroscopy and catalytic methods. It was found that the dehydrogenation of hexadecane occurred at 20–100°C with the subsequent formation of aromatic products, but the rates of these processes were very low. As the reaction temperature was increased to 200°C, the 4% Ni/Al2O3 catalyst exhibited a maximum activity and high selectivity for the formation of 1-hexadecene, and aromatic compounds and cracking products were present in the reaction products. As the reaction temperature was further increased, the catalytic activity significantly decreased. This was due to the fact that polyaromatic deposits gradually accumulated on the catalyst surface in a temperature range of 200–300°C.
- Chesnokov,Chichkan,Paukshtis,Chesalov, Yu. A.,Krasnov
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p. 439 - 445
(2019/09/04)
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- Branch-Selective Hydroarylation: Iodoarene-Olefin Cross-Coupling
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A combination of cobalt and nickel catalytic cycles enables a highly branch-selective (Markovnikov) olefin hydroarylation. Radical cyclization and ring scission experiments are consistent with hydrogen atom transfer (HAT) generation of a carbon-centered radical that leads to engagement of a nickel cycle.
- Green, Samantha A.,Matos, Jeishla L. M.,Yagi, Akiko,Shenvi, Ryan A.
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supporting information
p. 12779 - 12782
(2016/10/13)
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- PREPARATION OF SURFACTANTS VIA CROSS-METATHESIS
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The present invention relates to compositions comprising 2-phenyl linear alkene benzenes or 2-phenyl linear alkene benzene sulfonates or 2-phenyl linear alkylbenzenes or 2-phenyl linear alkylbenzene sulfonates; where the benzene ring is optionally substituted with one or more groups designated R *, where R * is defined herein and to methods for making the same. This invention also relates to compositions, methods of making, use of, and articles of manufacuture comprising 2-ethoxylated hydroxymethylphenyl linear alkyl benzenes or 2-propoxylated hydroxymethylphenyl linear alkyl benzenes.
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- Silylium ion/phosphane lewis pairs
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The reactivity of a series of silylium ion/phosphane Lewis pairs was studied. Triarylsilylium borates 4[B(C6F5)4] form frustrated Lewis pairs (FLPs) of moderate stability with sterically hindered phosphanes 2. Some of these FLPs are able to cleave dihydrogen under ambient conditions. The combination of bulky trialkylphosphanes with triarylsilylium ions can be used to sequester CO2 in the form of silylacylphosphonium ions 12. The ability to activate molecular hydrogen by reaction of silylium ion/phosphane Lewis pairs is dominated by thermodynamic and steric factors. For a given silylium ion increasing proton affinity and increasing steric hindrance of the phosphane proved to be beneficial. Nevertheless, excessive steric hindrance leads to a breakdown of the dihydrogen-splitting activity of a silylium/phosphane Lewis pair.
- Reissmann, Matti,Schaefer, Andre,Jung, Sebastian,Mueller, Thomas
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p. 6736 - 6744
(2014/01/06)
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- A novel catalyst for alkylation of benzene
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In this research, acid-activated and pillared montmorillonite were prepared as catalysts for alkylation of benzene with 1-decene for production of linear alkyl bebzene (LAB). The catalysts were characterized by X-ray diffraction (XRD), FT-IR spectroscopy,
- Faghihian, Hossein,Mohammadi, Mohammad Hadi
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p. 962 - 968
(2013/02/22)
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- Liquid phase alkylation of benzene with dec-1-ene catalyzed on supported 12-tungstophosphoric acid
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The liquid phase alkylation of benzene with dec-1-ene was catalyzed by 12-tungstophosphoric acid (WP) supported on different solids (ZrO2, SiO2, activated carbon and boehmite-Al2O3). Catalysts prepared with 20 w
- Hernández-Cortez,Martinez,Soto,López,Navarrete,Manríquez,Lara,López-Salinas
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scheme or table
p. 346 - 352
(2010/08/06)
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- Process for the production of phenylalkanes using a hydrocarbon fraction that is obtained from the Fischer-Tropsch process
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A process for the production of phenylalkanes comprising a reaction for alkylation of at least one aromatic compound by at least one hydrocarbon fraction that is directly obtained from the Fischer-Tropsch process comprising linear olefins that have 9 to 16 carbon atoms per molecule and oxygenated compounds is described. Said alkylation reaction is carried out in a catalytic reactor that contains at least one reaction zone that comprises at least one acidic solid catalyst, and said hydrocarbon fraction does not undergo any purification treatment prior to its introduction into said reaction zone.
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Page/Page column 4
(2008/06/13)
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- Zr-catalyzed coupling reaction of alkyl halides, tosylates, and sulfates with β-phenethyl Grignard reagents via styrene-zirconate intermediates
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β-Phenethylmagnesium chlorides react with alkyl halides, tosylates, and sulfates in the presence of a catalytic amount of Cp2ZrCl 2 to afford 2-arylalkanes via alkylation of styrene-zirconate intermediates at the benzylic position. Competitive reaction using mixtures of alkyl halides (alkyl-X; X = F, Cl, Br) showed that the reactivities of the halides increase in the order of alkyl-Cl alkyl-F alkyl-Br with the relative rates of 1:19:428. Georg Thieme Verlag Stuttgart.
- Terao, Jun,Begum, Shameem Ara,Oda, Akihiro,Kambe, Nobuaki
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p. 1783 - 1786
(2007/10/03)
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- Zr-Catalyzed Electrophilic Carbomagnesation of Aryl Olefins. Mechanism-Based Control of Zr-Mg Ligand Exchange
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(Formula Presented) The first examples of efficient electrophilic Zr-catalyzed carbomagnesations are disclosed, where in contrast to previous catalytic carbomagnesations the alkyl moiety of the electrophile is transferred (vs that of the Grignard reagent)
- De Armas, Judith,Hoveyda, Amir H.
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p. 2097 - 2100
(2007/10/03)
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- Zirconocene-catalyzed alkylation of aryl alkenes with alkyl tosylates, sulfates and bromides
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Styrenes were alkylated with alkyl tosylates, sulfates and bromides in the presence of a zirconocene catalyst and (n)BuMgCl in THF. By the use of this reaction, primary and secondary alkyl groups can be introduced regioselectively at the benzylic carbon of styrenes to give α-substituted ethylbenzenes.
- Terao, Jun,Watanabe, Tsunenori,Saito, Koyu,Kambe, Nobuaki,Sonoda, Noboru
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p. 9201 - 9204
(2007/10/03)
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- Catalytic Systems Based on Aluminum Chloride in Alkylation of Benzene with Olefins
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Two types of catalytic systems based on aluminum chloride and transition metal halides are prepared: mixed systems AlCl3-MeX (MeX is nickel, cobalt, copper, iron, tin, zinc, manganese, magnesium, potassium, or sodium chloride) and supported systems AlCl3/SiO2 and AlCl2·MeX/SiO2 (MeX is cobalt, nickel, or manganese chloride). Optimal conditions are found for preparation of catalytic systems based on aluminum chloride. These systems are studied in alkylation of benzene with olefins: ethene, propene, α-decene, and commercial C10-C14 fraction. Additives of nickel and cobalt chlorides increase the yield of ethyl- and propylbenzenes, simultaneously decreasing the yield of polyalkylbenzenes. Supported catalysts containing CoCl2, NiCl2, and FeCl3 additives increase the yield of monoalkylbenzenes in alkylation of benzene with higher olefins; additives of tin, zinc, and magnesium chlorides decrease the yield of monoalkylbenzenes; copper chloride is an inert additive. The yield of monoalkylbenzenes in alkylation of benzene with higher α-olefins in the presence of supported catalysts is 8-10% higher than in the presence of straight AlCl3. Preparation of supported catalytic systems requires 4-5 times smaller amount of aluminum chloride than preparation of binary systems.
- Polubentseva,Duganova,Mikhailenko
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p. 614 - 618
(2007/10/03)
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- Equilibria of isomeric transformations and relations between thermodynamic properties of secondary alkylbenzenes
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Equilibria of mutual transformations of monoamylbenzenes and diamylbenzenes (AmB), monohexylbenzenes (HxB), monoheptylbenzenes (HpB), and monodecylbenzenes (DB) have been studied in the liquid state over the range 273 to 423 K in the presence of 3 to 9 mass per cent of AlCl3.Values of ΔfH0m and ΔfS0m for the reactions studied have been calculated from the temperature dependences of the equilibrium constants.Below are given the reactions and the corresponding values for ΔfH0m/(kJ.mol-1) and ΔfS0m/(J.K-1.mol-1): 3-AmB=2-AmB, -(0.16 +/- 0.08), (8.45 +/- 0.23); 3-HxB=2-HxB, -(0.30 +/- 0.07), (3.85 +/- 0.21); 3-HpB=2-HpB, -(0.21 +/- 0.07), (3.52 +/- 0.22); 3-DB=2-DB, -(0.23 +/- 0.14), (3.51 +/- 0.43); 4-HpB=3-HpB, (0.02 +/- 0.41), (7.57 +/- 1.29); 4-DB=3-DB, (0.09 +/- 0.41), (1.69 +/- 1.28); 5-DB=4-DB, -(0.01 +/- 0.09), (0.18 +/- 0.25).For para-to-meta transformations of diamylbenzenes the average molar reaction enthalpy is -(0.26 +/- 0.46)kJ.mol-1 and the intrinsic change of molar entropy is -(0.99 +/- 1.2)J.K-1.mol-1.It is shown that for the calculation of enthalpies of formation of secondary alkylbenzenes correlations can be used which do not take into account the position of the phenyl substituent on the aliphatic hydrocarbon chain.The calculation of enthalpies of formation of normal and secondary alkylbenzenes in the liquid state at 298.15 K is made on the basis of experimental and literature values.
- Pimerzin, A. A.,Nesterova, T. N.,Rozhnov, A. M.
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p. 641 - 648
(2007/10/02)
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