- Aromatic Substitution in the Gas Phase. Alkylation of Arenes by Gaseous C4H9+ Cations
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Butyl cations, obtained in the dilute gas state from the radiolysis of butane in the pressure range from 70 to 750 torr, have been allowed to react with benzene, toluene, and their mixtures or with trace amounts of o-xylene in the gaseous system.The gas-phase butylation yields invariably sec-butylarenes, remarkably free of isomeric byproducts, namely n- and tert-butylarenes.Other alkylation experiments, where gaseous butyl cations from the reaction of butane with radiolytically formed H3+ ions were used as reagent, confirmed the exclusive formation of sec-butylarenes.The butylation process displays the positional and substrate selectivity and the dependence of orientation on the pressure of the system, typical of other gas-phase ionic substitutions.At high pressures, ortho-para orientation predominates in the sec-butylation of toluene, with a ortho:meta:para ratio of 43:30:27 at 715 torr.As the pressure is reduced, a gradual shift in favor of the thermodynamically most stable meta-subsltituted arenium ion is observed, leading to a ortho:meta:para ratio of 31:48:21 at 70 torr.
- Cacace, Fulvio,Ciranni, Giovanna,Giacomello, Pierluigi
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- Scandium(III) trifluoromethanesulfonate-catalyzed Friedel-Crafts alkylation of aromatic compounds with secondary alcohol methanesulfonates
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Scandium(III) inflate was found to be an efficient catalyst for the Friedel-Crafts alkylation of aromatic compounds with methanesulfonates derived from secondary alcohols; the catalyst can be reused without a significant loss of activity.
- Kotsuki, Hiyoshizo,Oshisi, Takeshi,Inoue, Motoshi
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Read Online
- Terminal-Selective Functionalization of Alkyl Chains by Regioconvergent Cross-Coupling
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Hydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C?H bond functionalization methods. We describe herein a new step-economical approach that enables C?C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross-coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross-coupling then provided access to the corresponding linear arylation product in only two steps.
- Dupuy, Stéphanie,Zhang, Ke-Feng,Goutierre, Anne-Sophie,Baudoin, Olivier
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p. 14793 - 14797
(2016/11/23)
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- Effects of the carbon support nature and ruthenium content on the performances of Ru/C catalysts in the liquid-phase hydrogenation of benzaldehyde to benzyl alcohol
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Abstract The hydrogenation of benzaldehyde in ethanol medium in the presence of Ru/C catalysts was shown to proceed with the preferential formation of benzyl alcohol without subsequent hydrodeoxygenation into toluene. An increase in ruthenium content of t
- Mironenko, Roman M.,Belskaya, Olga B.,Zaikovskii, Vladimir I.,Likholobov, Vladimir A.
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p. 923 - 930
(2015/08/06)
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- Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation
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Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total 'man-hours' in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl3, superior yields were observed with silica-gel bound aluminum chloride (Si-AlClx) when microwave irradiated for only 5 min.
- Zupp, Laurine R.,Campanella, Veronica L.,Rudzinski, Diandra M.,Beland, Franois,Priefer, Ronny
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p. 5343 - 5346
(2012/10/30)
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- Iron(II) complexes with functionalized amine-pyrazolyl tripodal ligands in the cross-coupling of aryl Grignard with alkyl halides
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Structurally distinctive Fe(ii) complexes with furan, thiophene and pyridine functionalized amine-pyrazolyl tripodal hybrid ligands have been synthesized and crystallographically characterized. The tether substituent at the central amine plays an active role in determining the coordination mode of the ligand and the metal geometry. All complexes are catalytically active towards cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides with β-hydrogen under ambient conditions. ESI-MS spectra analysis revealed the ligand-stabilised Fe(ii) and Mg(ii) species. The Royal Society of Chemistry 2011.
- Xue, Fei,Zhao, Jin,Hor, T. S. Andy
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experimental part
p. 8935 - 8940
(2011/10/19)
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- Synergistic effects of alkali metals in the alkylation of naphthalene and toluene with ethene in the ArH-alkali metal systems in THF (ArH - naphthalene, phenanthrene)
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The use of mixtures of metallic lithium and sodium in the naphthalene-alkali metal systems in THF leads to a synergistic acceleration of the naphthalene alkylation with ethene at room temperature and atmospheric pressure. The greatest synergistic effect is observed at a Li:Na molar ratio of 2:1. Under these conditions, the overall conversion of naphthalene into alkylation products (linear 1-alkylnaphthalenes and their dihydro derivatives) attains 88% after 24 h (a (Li + Na):C10H8 ratio is 2:1). The use of mixtures of metallic lithium and potassium in such systems results, however, in a synergistic retardation of the alkylation process. The strongest retarding effect is observed at a Li:K molar ratio of 1:1. The efficiency of the toluene alkylation with ethene in the naphthalene-alkali metal systems in THF is also increased on the replacement of lithium or sodium by their mixtures. The best results are obtained at a Li:Na molar ratio of 1:3. With this Li:Na ratio, toluene is almost quantitatively converted into linear and α-branched higher monoalkylbenzenes (24 h, (Li + Na):C10H8 = 2:1). The rate of the naphthalene alkylation with ethene in the presence of toluene is enhanced as well on an introduction of mixtures of lithium and sodium into the system. However the maximum of the activity is shifted here towards higher lithium content (Li:Na = 1:1). A similar synergistic effect of lithium and sodium was found on studying the toluene alkylation with ethene in the phenanthrene-Li-Na systems in THF (a (Li + Na):phenanthrene ratio is 3:1). An addition of potassium to sodium also considerably increases the efficiency of the toluene and naphthalene alkylation with ethene in the naphthalene-based systems. The possible mechanism of the alkali metal synergism in the above-mentioned alkylation reactions is discussed.
- Rummel,Yunusov,Kalyuzhnaya,Shur
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experimental part
p. 1467 - 1472
(2009/09/06)
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- Activation of C-H bonds of hydrocarbons by the ArH-alkali metal systems in THF (ArH - naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene, pyrene). Alkylation of naphthalene and toluene with ethene
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Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this reaction is exhibited by the naphthalene-potassium system which converts naphthalene into 1-ethylnaphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h, K:C10H8 = 2:1). The same alkylation products are formed when metallic sodium is used instead of potassium. The interaction of ethene with the naphthalene-lithium system (24 h, Li:C10H8 = 2:1) affords 1 together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5), 1-n-oktylnaphthalene (6) and dihydro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphthalene-alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C10H8 = 2:1), in the presence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of toluene with ethene at 22 °C. Of particularly active is the stilbene-lithium system (Li:stilbene = 3:1) which converts toluene into a mixture of 11-14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal. The mechanism of the reactions found is discussed.
- Rummel,Ilatovskaya,Yunusov,Kalyuzhnaya,Shur
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experimental part
p. 1459 - 1466
(2009/09/06)
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- Carbon-carbon coupling of C(sp3)-F bonds using alumenium catalysis
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Dialkylalumenium cation equivalents coupled with the hexabromocarborane anion function as efficient and long-lived catalysts for alkylation of aliphatic C-F bonds (alkylative defluorination or AlkDF) by alkylaluminum compounds. Only C(sp3)-F bo
- Gu, Weixing,Haneline, Mason R.,Douvris, Christos,Ozerov, Oleg V.
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experimental part
p. 11203 - 11212
(2009/12/05)
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- SYNTHESIS OF PROPYLBENZENE FROM TOLUENE AND ETHYLENE
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Methods are provided for producing alkylbenzenes, such as propylbenzene, from aromatics, such as toluene, and alkenes, such as ethylene. Such methods comprise combining the toluene with about 100 ppm to about 350 ppm water and alkali metal catalyst, activating the catalyst at about 18O°C to about 220°C, adding the ethylene and conducting the synthesis reaction at about 130°C to about 15O°C.
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Page/Page column 5-7
(2008/12/04)
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- A method of oxidizing perfluoroalkylated arom. compd.
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A process for the oxidation of an alkyl-aromatic compound, wherein the aromatic compound is admixed with an oxidising agent or sulfur compound in the presence of an ionic liquid is described. In this process, air, dioxygen, peroxide, superoxide, any other form of active oxygen, nitrite, nitrate, nitric acid or other oxides (or oxyhalides) of nitrogen (hydrate or anhydrous) are preferably used as the oxidising agent. The process is usually under Bronsted acidic conditions. The product of the oxidation reaction is preferably a carboxylic acid or ketone or an intermediate compound in the oxidation such as an aldehyde, or alcohol. The oxidation is preferably performed in an ionic liquid containing an acid promoter such as methanesulfonic acid.
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Page/Page column 7
(2008/06/13)
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- Pore-size engineering of silicon imido nitride for catalytic applications
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High specific surface areas and adjustable pore sizes are outstanding characteristics of nanoporous silicon nitride based materials prepared by using oxygen-free molecular precursors in a novel template-assisted sol-gel approach. The nitrides represent a new class of shape-selective superbase catalysts (see, for example, the schematic representation of alkene isomerization).
- Farrusseng, David,Schlichte, Klaus,Spliethoff, Bernd,Wingen, Annette,Kaskel, Stefan,Bradley, John S.,Schueth, Ferdi
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p. 4204 - 4207
(2007/10/03)
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- Sodium-potassium synergism in the alkylation of toluene and naphthalene with ethene in C10H8-Na-K systems in THF
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Sodium-potassium synergism in the alkylation of toluene and naphthalene with ethene in naphthalene-alkali metal systems in THF was discovered. In the case of toluene, the maximum synergistic effect is observed at an Na : K molar ratio of 1 : 1. With this Na : K molar ratio, the yields of the products of toluene alkylation with ethene considerably increase. The efficiency of naphthalene alkylation (in the presence of toluene) is also markedly enhanced on replacement of sodium or potassium by their mixture.
- Rummel,Yunusov,Langguth,Shur
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p. 2083 - 2085
(2007/10/03)
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- A new convenient Friedel-Crafts alkylation of aromatic compounds with secondary alcohol methanesulfonates in the presence of scandium(III) trifluoromethanesulfonate or trifluoromethanesulfonic acid as the catalyst
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Scandium(III) triflate and triflic acid were both found to be efficient catalysts for the Friedel-Crafts alkylation of aromatic compounds using methanesulfonates derived from secondary alcohols as alkylating agents.
- Kotsuki, Hiyoshizo,Ohishi, Takeshi,Inoue, Motoshi,Kojima, Tomoyuki
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p. 603 - 606
(2007/10/03)
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- Ionic hydrogenations of hindered olefins at low temperature. Hydride transfer reactions of transition metal hydrides
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Sterically hindered olefins can be hydrogenated at -50 °C in dichloromethane using triflic acid (CF3SO3H) and a hydride donor. Mechanistic studies indicate that these reactions proceed by hydride transfer to the carbenium ion that is formed by protonation of the olefin. Olefins that form tertiary carbenium ions upon protonation are hydrogenated in high yields (90-100%). Styrenes generally produce lower yields of hydrogenated products (50-60%). Suitable hydride donors include HSiEt3 and several transition metal carbonyl hydrides (HW(CO)3Cp, HW(CO)3Cp*, HMo-(CO)3Cp, HMn(CO)5, HRe(CO)5, and HOs(CO)2Cp*; Cp = η-C5H5, Cp* = η5-C5Me5). A characteristic that is required for transition metal hydrides to be effective is that the cationic dihydrides (or dihydrogen complexes) that result from their protonation must have sufficient acidity to transfer a proton to the olefin, as well as sufficient thermal stability to avoid significant decomposition on the time scale of the hydrogenation reaction. Metal hydrides that fail due to insufficient stability of their protonated forms include HMo(CO)2(PPh3)Cp, HMo(CO)3Cp*, and HFe(CO)2Cp*. Other hydrides that fail are those that are protonated to give dihydrides or dihydrogen complexes that are not sufficiently acidic to protonate olefins, as found for HW(CO)2(PMe3)Cp and HRu(CO)(PMe3)Cp.
- Bullock, R. Morris,Song, Jeong-Sup
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p. 8602 - 8612
(2007/10/02)
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- Electroorganic chemistry 139. Electroreductive decyanation of nitriles and its application to synthesis of α-alkylamines
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Electroreduction of nitriles gave the corresponding decyanated products when Zn was used as the material of cathode in aprotic solvent (DMF or MeCN) containing Et4NOTs as a supporting electrolyte. Alkylation of amines at the α-position was effectively achieved by cyanation of amines at the α-position, and α-alkylation of the resultant α-amino nitriles followed by the electroreductive decyanation.
- Shono, Tatsuya,Terauchi, Jun,Kitayama, Kenji,Takeshima, Yo-Ichiro,Masumura, Yoshihiro
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p. 8253 - 8262
(2007/10/02)
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- NiCl2(dppe)-Catalyzed Geminal Dialkylation of Dithioacetals and Trimethylation of Ortho Thioesters
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NiCl2(dppe)-catalyzed cross-coupling of cinnamaldehyde dithioacetals gave the corresponding geminal dimethylation products in excellent yields.Allylic ortho thioesters afforded regioselectively the corresponding trimethylation products.The reaction may occur via an 18-electron ?-allyl intermediate, which undergoes facile reductive elimination to afford the geminal dimethylation product.Benzylic dithioacetals having an ortho amino group gave 2-isopropylanilines exclusively.The reaction of benzylic dithioacetals with EtMgBr under the same conditions yielded geminal diethylation products.
- Tzeng, Yih-Ling,Yang, Ping-Fan,Mei, Nai-Wen,Yuan, Tien-Min,Yu, Chun-Chi,Luh, Tien-Yau
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p. 5289 - 5293
(2007/10/02)
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- Transition-State Polarization in Cleavage of C-C Bonds in Radical Anions
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The substituent effect on the rate of C-C bond cleavage in radical anions of 1-(4-nitrophenyl)-2-(substituted-phenyl)-1,1,2,2-tetraethylethanes has been explored.The data provide evidence for two distinctive modes of bond scission.One mode is characterized by a significant negative charge transfer across the scissile bond in the transition state.Such polarization of the transition state is in contradiction to the prediction based on the fragments' stability.The second mode, dominant in cases where the charge shift leads to negative charge accumulation on an already electron-rich fragment, involves a ?* radical anion.Both modes point to a general kinetic preference for a cleavage of radical anions that allows for charge delocalization across the scissile bond.
- Maslak, Przemyslaw,Narvaez, Javier N.,Kula, Jozef,Malinski, David S.
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p. 4550 - 4559
(2007/10/02)
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- Collision-induced Dissociations of Substituted Benzyl Negative Ions in the Gas Phase. The Elimination of C4H4
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The major collision-induced dissociation of PhEt2 involve the losses of H, H2, and CH4.Loss of H occurs from the phenyl ring, H2 is eliminated principally by the process while methane is lost by the stepwise process in which t
- Currie, Graeme J.,Bowie, John H.,Massy-Westropp, Ralph A.,Adams, Gregory W.
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p. 403 - 408
(2007/10/02)
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- Reductive Arylation of Vinyl Trifluoromethanesulfonates by Friedel-Crafts Reaction
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The reaction of vinyl triflates 1 with benzene and toluene in the presence of aluminium trichloride gives alkyl-, alkenyl-, and 1,1-diarylalkanes 5, 6, 3, 9 depending on the structure of the substrate used.A mechanism for the reductive arylation is proposed.
- Martinez, A. Garcia,Alvarez, R. Martinez,Fraile, A. Garcia,Hanack, Michael,Subramanian, L. R.
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p. 1255 - 1256
(2007/10/02)
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- Studies on the Regioselectivities in the Oxidation of Simple Alkyl Aromatic Hydrocarbons by Molecular Oxygen
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The products of the autoxidation of various simple alkyl aromatic hydrocarbons were reduced by LiAlH4, and the alcohols formed were determined by gas chromatography.In the cases of 2-phenylbutane, 3-phenylpentane, and 2-p-tolylbutane a considerable fragmentation of the intermediate tertiary alkoxy radicals was proved.On the basis of the analytical results relative reaction rates of the various C-H bonds in the hydrocarbons studied were calculated.It is shown that the attack at C-H bonds which are not activated by the aromatic nucleus cannot be neglected and may be of great importance for the kinetics of the oxidation of alkyl aromatic hydrocarbons.
- Pritzkow, Wilhelm,Thomas, Gerda,Willecke, Lothar
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p. 847 - 851
(2007/10/02)
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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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- Thermolabile Hydrocarbons, XXII. Thermolysis of symm. Tetraalkyldiarylethanes and the Resonance Energy of α,α-Dialkylbenzyl Radicals
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The products and the activation parameters for the thermolysis reactions of the hydrocarbons 1 - 10 were determined.From correlations between ΔG% and the ground state strain Hsp or the change in strain during the dissociation process Dsp the steric acceleration of this reaction was analyzed quantitatively.A comparison of this analysis with a corresponding correlation for simple Cq - Cq alkanes results in a resonance energie of 8.4 +/- 1.1 kcal * mol-1 for α,α-dialkylbenzyl radicals.The origin of the appreciable variation of ΔS% in this series and for the poorer precision of ΔH% /Hsp correlations is discuss ed.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Ruechardt, Christoph
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p. 1748 - 1764
(2007/10/02)
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- Carbanion Rearrangements by Intramolecular 1,ω Proton Shifts, III. The Reaction of 2-, 3-, 4-, and 5-Phenylalkyllithium Compounds
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Upon addition of THF to a solution of 4-phenylbutyllithium (2) in diethyl ether a rapid intramolecular 1,4 proton shift takes place with the formation of 1-phenylbutyllithium (5).Similarly, although somewhat more slowly, 5-phenylpentyllithium (82) rearranges to 1-phenylpentyllithium (83) via 1,5 proton transfer.The corresponding rearrangements by 1,2 or 1,3 hydrogen shifts, however, starting with 2-phenylethyllithium (1) and 3-phenylpropyllithium (54), respectively, were not detected.With 3-phenylpropyllithium (54) a slow intramolecular 1,5 transfer an ortho proton is observed instead, yielding o-propylphenyllithium (100).The corresponding 1,6 shift with 4-phenylbutyllithium (2) was also detected in a minor amount in addition to the 1,4 proton shift already mentioned.There is no indication, however, for a 1,4 transfer of an ortho proton in 2-phenylethyllithium (1).The reaction products in this case can be exclusively explained by intermolecular transmetallation reactions.All ω-phenylalkyllithium compounds under investigation show interesting side and secondary reactions being rather different in deuterated solvents and in deuteriumfree solvents, respectively, due to the isotope effects.The analysis of the products is accomplished by 1H-NMR spectroscopy and, after derivatization, with the help of a GC-MS-combination.Stereoelectronic reasons are made responsible for the failure of the intramolecular 1,2 and 1,3 proton shift in these systems.
- Maercker, Adalbert,Passlack, Michael
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p. 540 - 577
(2007/10/02)
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- LOW TEMPERATURE REACTION OF AROMATIC HYDROCARBONS WITH ETHYLENE AND SOLVATED ELECTRONS
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A wide variety of aromatic hydrocarbons can be ethylated at benzylic and aromatic positions by treatment with ethylene and potassium in glyme/octaglyme at -25 deg C.
- Russey, William, E.,Haenel, Matthias, W.
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p. 4065 - 4068
(2007/10/02)
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- COMPLEXES OF TRANSITION METALS IN THE CHEMISTRY OF CONJUGATED SYSTEMS. I. CATALYTIC ADDITION OF ORGANOMAGNESIUM AND ORGANOLITHIUM COMPOUNDS TO ENYNES AND THEIR DERIVATIVES
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Hydrocarbons with a conjugated system of double and triple bonds are capable of catalytic addition of arylmagnesium halides and aryllithiums at the triple bond in the presence of the salts and complexes of transition metals of group VIII.The β-diketonate complexes of Ni(II) and Fe(III) have the greatest activity.In the case of aryllithiums uncatalyzed addition reactions occur as well.Under the same conditions aliphatic Grignard reagents and alkyllithiums give a complex mixture of addition, reduction and oligomerizatin products.The direction of addition is determined solely by the character of substitution in the enyne system.The product yields are also determined by the nature of the metal and of the ligands in the catalyst and by the character of the organomagnesium and organolithium compound.The effect of polar and steric factors of the substituents at the triple bond in the alkyl, aryl, and trialkylsilyl series leads to a change in the direction of coordination and to the formation of the products from addition at the double bond.
- Zubritskii, L. M.,Fomina, T. N.,Bal'yan, Kh. V.
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