- Stereospecific Pd-catalyzed cross-coupling reactions of secondary alkylboron nucleophiles and aryl chlorides
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We report the development of a Pd-catalyzed process for the stereospecific cross-coupling of unactivated secondary alkylboron nucleophiles and aryl chlorides. This process tolerates the use of secondary alkylboronic acids and secondary alkyltrifluoroborates and occurs without significant isomerization of the alkyl nucelophile. Optically active secondary alkyltrifluoroborate reagents undergo cross-coupling reactions with stereospecific inversion of configuration using this method.
- Li, Ling,Zhao, Shibin,Joshi-Pangu, Amruta,Diane, Mohamed,Biscoe, Mark R.
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supporting information
p. 14027 - 14030
(2015/01/08)
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- Liquid-phase oxidation of isopropyl-meta-xylene to tertiary hydroperoxide
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Fundamental aspects and the mechanism of the reaction of liquid-phase oxidation of isopropyl-meta-xylene to a tertiary hydroperoxide by atmospheric oxygen, initiated by isopropylbenzene hydroperoxide or catalyzed by N-hydroxyphthalimide were studied. It was found that using N-hydroxyphthalimide in the course of oxidation of isopropyl-meta-xylene makes it possible to raise, compared with the initiator (isopropylbenzene hydroperoxide), the oxidation rate and the conversion of the hydrocarbon by a factor of 2-2.5 at a 90-95% formation selectivity of a tertiary hydroperoxide of isopropyl-meta-xylene up to a conversion of 20-25%.
- Frolov,Kurganova,Koshel
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p. 895 - 898
(2015/01/08)
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- K-promoted Mo/Co- and Mo/Ni-catalyzed Fischer-Tropsch synthesis of aromatic hydrocarbons with and without a Cu water gas shift catalyst
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The catalyst systems Mo/Co/K/ZSM-5 and Mo/Ni/K/ZSM-5, alone and with the added copper-based water gas shift catalyst, were used for the conversion of two CO/H2 ratios in a batch reactor. GC analysis of the gas phase was used to determine CO conversion while GCMS and NMR studies were used to characterize the liquid products formed and liquid product selectivities. The liquids were hydrocarbons consisting mainly of alkyl substituted benzenes. Methyl substitution in the alkyl benzenes in the product liquid ranged from an average of 1.3 to 4.5 methyls per ring depending on reaction conditions and reactant gas mole ratios. The additional presence of the WGS catalyst significantly increased CO conversion in the reactions taking place at 280 °C from ~25% to ~90% while increasing selectivity toward higher average methyl substitution. Similar conversions and selectivities were observed with both a bio-syngas and a 50/50 mixture of H2 and CO.
- Wijayapala, Rangana,Yu, Fei,Pittman Jr., Charles U.,Mlsna, Todd E.
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- PROCESS FOR PRODUCING ALKYLAROMATIC COMPOUND
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A process is provided for producing an alkyl aromatic compound having substituents at the 3- and 5-positions by alkylating an aromatic compound having two substituents in the meta positions with an olefin having 2 to 4 carbon atoms in the presence of a Broensted acid, followed by addition of a Lewis acid and isomerization in the copresence of the Broensted acid and the Lewis acid. According to the present invention, 3,5-dimethylethylbenzene, 3,5-dimethylcumene, etc. may be produced in a stable manner with high yield and high selectivity under mild and simple reaction conditions. The alkyl aromatic compounds having substituents at the 3- and 5-positions are useful as intermediates for functional chemicals for use in pharmaceutical, agricultural and electronic materials. With the method of the present invention, the catalyst used can be recovered and recycled. Thus, desired alkyl aromatic compounds may be obtained economically in an industrially advantageous manner while reducing the load on the environment.
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Page/Page column 7
(2008/06/13)
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- Isopropylation of xylenes catalyzed by ultrastable zeolite Y (USY) and some other solid acid catalysts
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The isopropylation of all three xylene isomers was carried out over ultrastable zeolite Y (USY) catalyst to give corresponding dimethyl (1-methylethyl) benzenes, or in other words dimethyl cumenes (DMCs), using isopropanol as alkylating agent. The effect of reaction temperature, space velocity, substrate-to-alkylating-agent molar ratio, and time-on-stream on conversion of xylene isomers and selectivity to dimethyl cumene was studied. Isopropylation of xylenes over USY gives quite high (80 to 95%) DMC selectivity among the dimethyl cumenes, along with a 70-90% yield of DMCs in total products with respect to limiting reagents, i.e., isopropylating agents at relatively low reaction temperatures (423 ± 10 K) and at quite high xylene conversions (85-97% of theoretical maximum value). The solid acid catalysts zeolites H-Y, H-beta, H-mordenite, as well as silica-alumina and sulfated zirconia, were included for comparative studies in the isopropylation of m-xylene.
- Patra, Chitta Ranjan,Kumar, Rajiv
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p. 216 - 224
(2007/10/03)
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- SILICA-ALUMINA SUPPORTED TRANSITION METAL OXIDE CATALYST FOR ALKYLATION OF AROMATIC COMPOUNDS
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Titanium oxide on silica-alumina support is described to be an efficient regenerable catalyst for alkylation of aromatic compounds with alkyl halides, alcohols and olefins, and the reaction is proposed to be initiated by the protonated metal active species present in the catalyst.
- Kumar, V. G.,Shoba, T. S.,Rao, K. V. C.
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p. 3281 - 3284
(2007/10/02)
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- Alkyltrifluoromethanesulphonates as alkylating reagents for aromatic compounds
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Methyl and ethyl trifluoromethanesulphonates (' triflates '), prepared by conventional routes involving either trifluoromethanesulphonic acid (' triflic acid ') or its anhydride, contain traces of triflic acid as an impurity, which catalyse their alkylation reactions with aromatic compounds. Pure methyl triflate, obtained from reaction between CH3l and CFS03Ag, does not alkylate p-cymene after several hours at 100 °C. Pure ethyl triflate, prepared by a similar method, is thermally less stable under these conditions, and alkylation takes place only after long induction periods during which some breakdown to triflic acid occurs. With aromatic substrates such as p-cymene or mesitylene the onset of alkylation is followed rapidly by the formation of isomerisation and disproportionation products. Benzyl triflate, prepared from PhCH2Br and CF3SO3Ag, alkylates p-cymene even at room temperature. The strong Lewis acids SbF5 and AlCl3 similarly catalyse alkylation reactions of methyl and ethyl triflates, but BF3, FeCl3, and SnCl4 are much less effective.
- Booth, Brian L.,Haszeldine, Robert N.,Laali, Khosrow
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p. 2887 - 2893
(2007/10/02)
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