- Activation of C-S bond by group 10 metal complexes: Reaction of phosphine ligand tethered with three tert-butylthiophenyl groups with group 10 metal compounds
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A new PS3-type tripodal tetradentate ligand, P(2-t-BuSC6H4)3 (1b), was synthesized by reaction of PCl3 with 2-t-BuS(C6H4)Li. Reaction of ligand 1b with NiCl26H2O resulted in the elimination of t-BuCl to afford the corresponding 5-coordinate nickel complex, [NiCl(P(2-SC6H4)(2-t-BuSC6H4)2}] 6. In addition, ligand 1b reacted with [PdCl2(PhCN)2] and [PtCl2(cod)] to give 4-coordinate square planar palladium and platinum complexes, [MCl(P(2-SC6H4)(2-t-BuSC6H4)2}] (7: M = Pd, 8: M = Pt), respectively, via the elimination of t-BuCl. Further elimination of t-BuCl from palladium complex 7 proceeded by heating of 7 in CDCl3 at 100°C for 4h to form dipalladium complex, [Pd2(P(2-SC6H4)2(2-t-BuSC6H4))2] (9). The isopropyl-substituted palladium and platinum complexes, [PdCl{P(2-i-PrSC6H4)3}]Cl (3a) and [PtCl2{P(2-i-PrSC6H4)3}] (5), also underwent the elimination of i-PrCl by the thermolysis in CDCl3 at 60 °C to afford the corresponding complexes, [MCl{P(2-SC6H4)(2-i-PrSC6H4)2}] (11: M = Pd, 12: M = Pt). The structures of these complexes were determined by NMR spectroscopy, elemental analyses, and X-ray crystallography.
- Takeda, Nobuhiro,Tanaka, Yusuke,Oma, Rin,Sakakibara, Fumiaki,Unno, Masafumi
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Read Online
- Stabilities of Carbonium Ions in Solution. 12. Heats of Formation of Alkyl Chlorides as an Entree to Heats of Solvation of Aliphatic Carbonium Ions
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Heats of formation (ΔHf) of tertiary alkyl chlorides may be calculated from measurements of the heats of hydrochlorination of appropriate olefins at -50 deg C in CH2Cl2.Since many good values for heats of formation of the olefins have been published, the heats of hydrochlorination lead directly to ΔHf for the chlorides, for which few previous values are available.The new data, when combined with previously reported heats of ionization for the chlorides, provide heats of formation for the carbonium ions.Relative values for ΔHf for the carbonium ions are remarkably similar in the gas phase and in SO2ClF, thus supporting the proposal that differential solvation of carbonium ions is small in solvents such as SO2ClF.Because solvation energies are nearly constant for carbonium ions, their relative energies as calculated from quantum theory should apply directly to nonnucleophilic condensed phase values - a situation which is drastically different from that for ammonium or oxonium ions.We have shown previously the close relationship between ionization energies for alkyl chlorides in SO2ClF and their solvolysis rates in ethanol.The present results complete the series of data which are necessary for rigorously relating theoretical calculations of carbonium ion stability to solvolysis reaction rates in solution.Thereby, they help to explain the great success of the carbonium ion theory of organic chemistry.
- Arnett, Edward M.,Pienta, Norbert J.
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Read Online
- Matrix Isolation Study of Complexation and Exchange Reactions of Molecular Halogens with tert-Butyl Halides
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The 1/1 molecular complexes of tert-butyl chloride and bromide with ClF, Cl2 and Br2 have been isolated and characterized in argon matrices following twin-jet deposition.Perturbed vibrational modes of the tert-butyl halide, including the carbon-halogen stretching and the CH3 rocking modes, were observed upon complex formation.For the ClF complexes, the red-shifted Cl-F stretching mode was observed as well.The twin-jet codeposition of (CH3)3Br with Cl2 and ClF led to the exchange reaction product (CH3)3CCl, despite the very short mixing time in these experiments.The single-jet codeposition of these pairs of reactants led to further reactions, forming tert-butyl fluoride in the ClF experiments and 1,2-dichloro-2-methylpropane in the reactions of (CH3)3CCl and (CH3)3CBr with Cl2.While the halogen-exchange reactions are very facile, these results support the intermediacy of molecular complexes during the reaction process.
- Bai, Hebi,Ault, Bruce S.
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- UN NOUVEAU DIPHOSPHENE STABLE : LE BISDIPHOSPHENE
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A new stable diphosphene (Me3Si)3C-P=P-C(SiMe3)3 has been isolated and characterized particularly by its NMR data; the 31P NMR chemical shift appears to be the largest ever observed.
- Couret, Claude,Escudie, Jean,Satge, Jacques
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Read Online
- Kinetics of the Reactions of Methyl, Ethyl, Isopropyl, and tert-Butyl Radicals with Molecular Chlorine
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The gas-phase kinetics of the reactions of four alkyl radicals (CH3, C2H5, i-C3H7, and t-C4H9) with molecular chlorine have been studied over limited temperature ranges.The reactions were isolated for quantitative study in a tubular reactor coupled to a photoionization mass spectrometer.The radicals were homogeneously generated in the reactor by pulsed photolysis of suitable precursor molecules at 193 nm.The subsequent decays of the radical concentration in the presence of different molecular chlorine concentrations were monitored in real-time experiments.For each reaction studied, rate constants (k) were measured at a minimum of five temperatures.The temperature-dependent expressions for log k derived from these studies for the four R + Cl2 -> RCl + Cl reactions and the temperature ranges covered are as follows: R = CH3 , 296-712 K; R = C2H5 , 295-498 K; R = i-C3H7 , 298-498 K; R = t-C4H9 , 298-498 K.Units are cm3 molecule-1 s-1.The measured rate constants, their closeness to those of corresponding R + O3 rate constants, and the results of a prior study of the dynamics of the CH3 + Cl2 reaction indicate that the reactivity of alkyl radicals with molecular chlorine is determined largely by long-range attractive forces.
- Timonen, Raimo S.,Gutman, David
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Read Online
- Hydrochlorination of Alkenes. 2. Reaction of Gases Hydrogen Chloride and 2-Methylpropene
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Mixtures of gaseous hydrogen chloride and gaseous 2-methylpropene at total pressures less than 1 atm yield, exclusively, gaseous 2-chloro-2-methylpropane.Kinetic measurements have been made by proton magnetic resonance and infrared spectroscopy and by observing the pressure change accompanying the reaction.It is concluded that surface catalysis is required for product formation and that the reaction, which occurs at the walls, is most probably between strongly adsorbed hydrogen chloride and weakly adsorbed 2-methylpropene; i.e., a Rideal-Eley mechanism obtains.
- Costello, Francis,Dalton, David R.,Poole, John A.
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Read Online
- Method for synthesizing musk xylene from gamma-lactone byproduct azeotrope
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The invention discloses a method for synthesizing musk xylene from a gamma-lactone byproduct azeotrope. The method comprises the following steps: 1, carrying out chlorination reaction on tert-butyl alcohol namely a byproduct in the production process of gamma-lactone and hydrochloric acid to obtain chloro-tert-butane; 2, carrying out a condensation reaction on chloro-tert-butane and m-xylene, neutralizing, washing with water, and distilling to recover m-xylene so as to obtain 1,3-dimethyl-5-tert-butyl benzene; and 3, carrying outnitration reaction on 1,3-dimethyl-5-tert-butyl benzene to obtain a musk xylene crude product, carrying out neutralization washing, crystallization, centrifugation and a series of separation and purification to obtain a 99% musk xylene product. An initiator di-tert-butyl peroxide used in the production process of gamma-lactone is hydrolyzed, the high-content musk xylene is prepared from the generated byproduct 80% tert-butyl alcohol and a water azeotrope starting raw material through chlorination, condensation and nitration reactions, the synthesis steps are relatively simple, and the byproduct resources are comprehensively utilized.
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Paragraph 0044-0049; 0059-0064
(2021/04/17)
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- Aryloxy Triester Phosphoramidates as Phosphoserine Prodrugs: A Proof of Concept Study
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The specific targeting of protein-protein interactions by phosphoserine-containing small molecules has been scarce due to the dephosphorylation of phosphoserine and its charged nature at physiological pH, which hinder its uptake into cells. To address these issues, we herein report the synthesis of phosphoserine aryloxy triester phosphoramidates as phosphoserine prodrugs that are enzymatically metabolized to release phosphoserine. This phosphoserine-masking approach was applied to a phosphoserine-containing inhibitor of 14-3-3 dimerization, and the generated prodrugs exhibited improved pharmacological activity. Collectively, this provided a proof of concept that the masking of phosphoserine with biocleavable aryloxy triester phosphoramidate masking groups is a viable intracellular delivery system for phosphoserine-containing molecules. Ultimately, this will facilitate the discovery of phosphoserine-containing small-molecule therapeutics.
- Dhiani, Binar A.,James, Edward,Kadri, Hachemi,Lambourne, Olivia A.,Mehellou, Youcef,Miccoli, Ageo,Thornton, Peter J.
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supporting information
(2020/03/30)
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- Method for co-producing methyl chloropropene and 2-chloro-2-methylpropane by chlorination of isobutene
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The invention discloses a method for co-producing methyl chloropropene and 2-chloro-2-methylpropane by chlorination of isobutene. According to the method, a chlorination reaction is carried out on chlorine or a mixture of chlorine and inert gas and excessive isobutene to obtain products, namely methyl chloropropene and 2-chloro-2-methylpropane. The method can reduce influence of micro-mixing on arapid chlorination reaction of isobutene, decarburization and coking do not occur easily, and 2-chloro-2-methylpropane can be co-produced while the yield of methyl chloropropene is improved.
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Paragraph 0023; 0024; 0026
(2020/01/12)
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- Chlorinating preparation method for low-carbon olefins
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The invention discloses a chlorinating preparation method for low-carbon olefins. According to the method, chlorine gas is diluted with inert gas and then reacts with low-carbon olefins, thus, influence caused by microscopic mixing can be obviously reduced, namely, a too high local temperature can be avoided, thus, side reactions including a decarbonization phenomenon caused by the too high localtemperature can be obviously reduced, and a relatively good chloride yield can be obtained.
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Paragraph 0037-0039
(2020/01/12)
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- Protecting and Leaving Functions of Trimethylsilyl Groups in Trimethylsilylated Silicates for the Synthesis of Alkoxysiloxane Oligomers
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The concept of protecting groups and leaving groups in organic synthesis was applied to the synthesis of siloxane-based molecules. Alkoxy-functionalized siloxane oligomers composed of SiO4, RSiO3, or R2SiO2 units were chosen as targets (R: functional groups, such as Me and Ph). Herein we describe a novel synthesis of alkoxysiloxane oligomers based on the substitution reaction of trimethylsilyl (TMS) groups with alkoxysilyl groups. Oligosiloxanes possessing TMS groups were reacted with alkoxychlorosilane in the presence of BiCl3 as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO3 and R2SiO2 units were synthesized more efficiently than those composed of SiO4 units, suggesting that the steric hindrance around the TMS groups of the oligosiloxanes makes a difference in the degree of substitution. This reaction uses TMS groups as both protecting and leaving groups for SiOH/SiO? groups.
- Yoshikawa, Masashi,Tamura, Yasuhiro,Wakabayashi, Ryutaro,Tamai, Misa,Shimojima, Atsushi,Kuroda, Kazuyuki
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supporting information
p. 13990 - 13994
(2017/10/31)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- Preparation method of tert-butyl chloride
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The invention discloses a preparation method of tert-butyl chloride. The tert-butyl chloride is synthesized through a chlorination reaction of tert-butyl alcohol under the catalysis of a metal chloride. The metal chloride is added as a catalyst in the preparation method, so the method has the advantages of simple production process, less device investment, realization of the reaction rate reaching 95% or above, and realization of the purity of a gas phase reaching 99.5% or above.
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Paragraph 0018
(2017/02/09)
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- Tertiary butyl-containing spirobifluorene compound and preparation and application thereof
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The invention relates to a tertiary butyl-containing spirobifluorene compound and preparation and application thereof. The material has the following general formula (I) shown in the description, wherein R is a structure shown in the description; -Ar shown in the description, wherein -Ar is selected from at least one of the following structural units or derivatives of the following structural units: shown in the description; in the above mentioned structural formulas, m and n are integers of 0 to 8, and R1, R2, R3 and R4 are hydrogen, or straight chains or branched chains or ring alkyl or oxyalkyl chains with 1 to 22 carbon atoms, and can be the same or different. Compared with the prior art, the tertiary butyl-containing spirobifluorene compound disclosed by the invention has the advantages that 4,4'-ditert-butyl-2-brominated biphenyl with low cost replaces 2-brominated biphenyl which is generally used in the conventional 9,9'-spirobifluorene preparation process and is high in cost, and the synthesis method has the characteristics of low cost, simple synthesis route, high yield, easiness in industrial production and the like; a spirobifluorene hole-transmission/electroluminescent material is high in hole-transmission performance and electroluminescent performance.
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Paragraph 0107; 0108; 0109; 0110
(2017/02/17)
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- Reactivity of [WCl6] with Ethers: A Joint Computational, Spectroscopic and Crystallographic Study
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The reactions of [WCl6] with a series of ethers have been performed in chlorinated solvent and elucidated by means of analytical, spectroscopic and DFT methods. The addition of tetrahydropyran (thp) or 1,4-dioxane to [WCl6] resulted in the reversible formation of the adducts WCl6···L [L = thp (1a), 1,4-dioxane (1b)], detected in solution by NMR spectroscopy. The reaction of [WCl6] with thp in a molar ratio of 1:2 in chloroform at reflux afforded [WOCl4(thp)] (2a), which was isolated in 51 % yield. [WOCl4(OMe2)] (2b) and [WOCl3(OMe2)2] (3a) were isolated in yields of 53 and 18 %, respectively, from the reaction of [WCl6] with an excess of dimethyl ether. [WOCl3(OEt2)2] (3b) was the only identified metal compound produced from the reaction of [WCl6] and OEt2(1:2 molar ratio). According to NMR studies, the oxide ligand in 2a,b and 3a,b was generated by double C–O bond cleavage involving one equivalent of organic reactant. The 1:1 reaction of [WCl6] with 1,2-diethoxyethane led to [WCl5(κ1-OCH2CH2OEt)] (4) and a minor amount of [WCl4(κ2-EtOCH2CH2OEt)] (5). The aryl oxide compound [WCl5(OPh)] (6) was prepared in 62 % yield from the reaction of [WCl6] and anisole by selective Csp3–O bond activation. The prolonged heating of a mixture of [WCl6] and diphenyl ether in 1,2-dichloroethane led to the isolation of the WVcomplex [WCl5(OPh2)] (7). The molecular structures of 2a and 3a were ascertained by X-ray diffraction.
- Bortoluzzi, Marco,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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p. 3169 - 3177
(2016/07/14)
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- A convenient method for producing mono- and dichlorohydrins from glycerol
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A new method for the transformation of glycerol into mono- and dichlorohydrins has been studied. With trimethylchlorosilane as chlorinating agent and acetic acid as catalyst, mono- and dichlorohydrins have been obtained in high yields and selectivity. In fact, under different reaction conditions, the synthesis of α-monochlorohydrin (3-chloropropan-1,2-diol) or α,γ-dichlorohydrin (1,3-dichloropropan-2-ol) as predominant product has been achieved. This process was also exploited for the valorisation of the crude mixture of glycerol and monochlorohydrin (glyceric mixture), a by-product from an earlier BioDiesel production. A reaction mechanism has been proposed based on investigations on the chlorination of different alcohols.
- Giomi, Donatella,Malavolti, Marino,Piccolo, Oreste,Salvini, Antonella,Brandi, Alberto
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p. 46319 - 46326
(2015/02/19)
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- Reaction of P(III) chlorides with aldehydes: III. Reaction of primary intermediates with oxidants and chlorinating agents
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Primary intermediates of P(III) chlorides reaction with aldehydes have been converted into the corresponding phosphates by treating with oxidants: dimethylsulfoxide and tert-butyl hypochlorite. In reactions of the intermediates with chlorinating agents (P
- Gazizov,Khairullin,Karimova
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- Conjugate addition reactions of N -carbamoyl-4-pyridones and 2,3-dihydropyridones with grignard reagents in the absence of Cu(I) Salts
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N-Boc- and N-ethoxycarbonyl-4-pyridones and the resulting 2,3-dihydropyridones undergo 1,4-addition reactions with Grignard reagents in the presence of chlorotrimethylsilane (TMSCl) or BF3·Et 2O in excellent yields. Copper catalysis is not required, and mechanistic considerations suggest that the reaction is proceeding by a conjugate addition pathway rather than by a pathway involving 1,2-addition to an intermediate pyridinium ion. TMSCl-mediated conjugate addition of Grignard reagents to 2-substituted-2,3-dihydropyridones gives the trans-2,6-disubstitued piperidinones stereoselectively, while cuprate reagents give either the trans or cis diastereomers or mixtures.
- Guo, Fenghai,Dhakal, Ramesh C.,Dieter, R. Karl
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p. 8451 - 8464
(2013/09/24)
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- Catalytic phosphorus(V)-mediated nucleophilic substitution reactions: Development of a catalytic appel reaction
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Catalytic phosphorus(V)-mediated chlorination and bromination reactions of alcohols have been developed. The new reactions constitute a catalytic version of the classical Appel halogenation reaction. In these new reactions oxalyl chloride is used as a consumable stoichiometric reagent to generate the halophosphonium salts responsible for halogenation from catalytic phosphine oxides. Thus, phosphine oxides have been transformed from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilic substitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including density functional theory calculations on proposed intermediates of the catalytic cycle, are consistent with a catalytic cycle involving halo- and alkoxyphosphonium salts as intermediates.
- Denton, Ross M.,An, Jie,Adeniran, Beatrice,Blake, Alexander J.,Lewis, William,Poulton, Andrew M.
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experimental part
p. 6749 - 6767
(2011/10/02)
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- PROCESS FOR SELECTIVELY POLYMERIZING ETHYLENE AND CATALYST THEREFOR
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The present invention generally relates to a process that selectively polymerizes ethylene in the presence of an alpha-olefin, and to a metal-ligand complex (precatalyst) and catalyst useful in such processes, and to related compositions. The present invention also generally relates to ligands and intermediates useful for preparing the metal-ligand complex and to processes of their preparation.
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Page/Page column
(2013/03/26)
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- Liquid-phase isobutane/butene-alkylation using promoted Lewis-acidic IL-catalysts
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The effect of different promoters on activity and selectivity of Lewis-acidic chloroaluminate ionic liquid catalysts was studied for isobutane/2-butene alkylation. When tert-butyl halides are used as promoters, the active species of the alkylation reaction, which is the tert-butyl cation, is directly generated whereas upon catalysis with Bronsted-acid supported ionic liquids, this species is indirectly provided through a hydride shift between protonated 2-butene and isobutane. Experimental results both from batch and continuously operated liquid phase alkylation reactors indicate, that tert-butyl halides are able to speed up the reaction rate significantly and shift the C8-selectivity towards the desired high-octane trimethylpentanes (TMPs). However, secondary reactions like oligomerization and cracking could not be suppressed by the use of this additives and high deactivation rates in continuous opperation were observed. Suggestions are made, how the product composition is effected by the additive and how the promoted IL-catalyst system is deactivated with time on stream.
- Aschauer, Stephan,Schilder, Lisa,Korth, Wolfgang,Fritschi, Susanne,Jess, Andreas
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body text
p. 1405 - 1419
(2012/06/18)
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- Practical conversion of chlorosilanes into alkoxysilanes without generating HCl
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Alcohol-free: A versatile, efficient, and practical synthesis of alkoxysilanes without generation of HCl involves the reaction of chlorosilanes with unsymmetrical ethers in the presence of a Lewis acid (see scheme). The reaction proceeds through selective cleavage of C-O bonds and is superior to conventional processes. Industrially feasible reagents are used and only one by-product results. Copyright
- Wakabayashi, Ryutaro,Sugiura, Yasushi,Shibue, Toshimichi,Kuroda, Kazuyuki
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supporting information; experimental part
p. 10708 - 10711
(2011/12/05)
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- Kinetics and mechanism of N-Boc cleavage: Evidence of a second-order dependence upon acid concentration
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The kinetics of the HCl-catalyzed deprotection of the Boc-protected amine, thioester 2 to liberate AZD3409 1 have been studied in a mixture of toluene and propan-2-ol. The reaction rate was found to exhibit a second-order dependence upon the HCl concentration. This behavior was found to have a degree of generality as the deprotection of a second Boc-protected amine, tosylate 3 to yield amine 4 using HCl, sulfuric acid, and methane sulfonic acid showed the same kinetic dependence. In contrast the deprotection of tosylate 3 with trifluoroacetic acid required a large excess of acid to obtain a reasonable rate of reaction and showed an inverse kinetic dependence upon the trifluoroacetate concentration. These observations are rationalized mechanistically in terms of a general acid-catalyzed separation of a reversibly formed ion-molecule pair arising from the fragmentation of the protonated tert-butyl carbamate.
- Ashworth, Ian W.,Cox, Brian G.,Meyrick, Brian
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supporting information; body text
p. 8117 - 8125
(2011/02/26)
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- Reactions of α-Diimine Ligands with the in situ generated s(OTf)2 synthon
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A series of reactions of α-diimine ligands with a 2:1 mixture of SCl2 and trimethylsilyltrifluormethanesulfonate(TMS-OTf), which behaves as an S(OTf)2 synthon, were performed. The reactivity was shown to differ based on the substitution at the nitrogen atoms of the ligand as aromatic groups yielded dicationic sulfur nitrogen heterocycles whereas alkyl groups resulted in the loss of one of the organic substituents at nitrogen giving monocationic 1,2,5-thiadiazolium rings. The substitution on the backbone carbon being a hydrogen atom, phenyl group (diazabutadiene; DAB) or acenaphthene (bisiminoacenaphthene, BIAN) proved not to be influential on the outcome of the reaction as both systems resulted in N,N′-chelated dications. These are rare examples of sulfur structural mimics of the N-heterocyclic silylene, and the BIAN species represent the first complexes of sulfur with this ubiquitous ligand.
- Martin, Caleb D.,Ragogna, Paul J.
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experimental part
p. 4324 - 4330
(2010/07/04)
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- Reactions of atomic carbon with acyl chlorides
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Reactions of arc-generated carbon atoms with acyl chlorides proceed by two distinct mechanistic pathways depending on the nature of the alkyl group in the substrate. Acetyl chloride affords vinyl chloride from the putative chloromethylcarbene produced by deoxygenation, whereas pivaloyl chloride gives t-butyl chloride as the predominant product via a chain reaction from the initially generated pivaloyl radical. When the alkyl group is isopropyl, both pathways are implicated.
- Herrick, Daniel B.,Thamattoor, Dasan M.,Shevlin, Philip B.
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scheme or table
p. 6036 - 6038
(2009/04/04)
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- Chlorinations of derivatives of 2,2,2-trichlorobenzo-1,3,2-dioxaphospholes
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By 31P, 13C, 13C-{1H}, and 1H NMR spectroscopy the chlorination of 4-and 5-methyl-2,2,2- trichlorobenzo-1,3,2-dioxaphosphols was shown to provide in quantitative yield 4-methyl-2,2,2,5-tetrachloroand
- Varaksina,Mironov,Shtyrlina,Dobrynin,Cherkin,Gubaidullin,Litvinov,Konovalov
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experimental part
p. 988 - 999
(2009/06/18)
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- Determination of critical temperatures for mixtures of alkylbenzenes
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The liquid-vapor critical temperatures of benzene mixtures with 1,3-di-tert-butylbenzene, 1,4-di-tert-butylbenzene, and 1,3,5-tri-tert- butylbenzene; a mixture of di-tert-butylbenzene isomers; and a toluene mixture with 3,5-di-tert-butyltoluene were determined over the entire range of composition by means of the amouule method. It was found that the excess critical temperature of the mixtures is related to the critical volumes of the substances. The capabilities of several calculation methods for predicting the critical temperature of mixtures were analyzed on the basis of published data and the obtained results. The Lee-Kesler rules of mixtures were refined by introducing binary interaction parameters.
- Nesterov,Nazmutdinov,Sarkisova,Nesterova,Vodenkova
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p. 434 - 441
(2008/09/16)
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- Selective formation of chloroethane by the hydrochlorination of ethene using zinc catalysts
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A detailed study of the hydrochlorination of ethene and higher alkenes using ZnCl2/SiO2 and ZnCl2/Al2O3 catalysts is described and discussed. Based on earlier observations that supported gold can be an active catalyst for both ethyne hydrochlorination and oxidation reactions, we initially investigated using supported gold as catalysts for the oxychlorination of ethene. However, we found that oxychlorination did not occur in the presence of oxygen and, furthermore, that the gold acted as a poison/inhibitor during the initial reaction period, with the underlying reaction being ethene hydrochlorination. Supported Zn2+ was found to be a very effective catalyst for this reaction. The hydrochlorination of higher alkenes occurred, with high selectivity to a range of relatively complex chlorinated hydrocarbon products at rates of ca. 10-13 mol/(kgcat h).
- Conte, Marco,Davies, Thomas,Carley, Albert F.,Herzing, Andrew A.,Kiely, Christopher J.,Hutchings, Graham J.
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- Microwave-assisted generation of alkoxyl radicals and their use in additions, β-fragmentations, and remote functionalizations
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Microwave irradiation (2.45 GHz, 300-500 W) of N-(alkoxy)thiazole-2(3H)- thiones in low-absorbing solvents affords alkoxyl radicals, which were identified by (i) spin adduct formation (EPR-spectroscopy) and (ii) fingerprint-type selectivities in intramolecular additions (stereoselective synthesis of disubstituted tetrahydrofurans), β-fragmentations (formation of carbonyl compounds), and C,H-activation of aliphatic subunits, by δ-selective hydrogen atom transfer. C-Radicals formed from oxygen-centered intermediates were trapped either by Bu3SnH, l-cysteine ethyl ester, the reduced form of glutathione (reductive trapping), or by bromine atom donor BrCCl3 (heteroatom functionalization) The results suggest that microwave activation is superior to UV/Vis-photolysis and conductive heating for alkoxyl radical generation from N-(alkoxy)thiazolethiones. It offers by far the shortest reaction times along with the option to reduce the amount of trapping reagent significantly. The Royal Society of Chemistry 2006.
- Hartung, Jens,Daniel, Kristina,Gottwald, Thomas,Gross, Andreas,Schneiders, Nina
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p. 2313 - 2322
(2008/02/08)
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- Oxidation of monohydric and dihydric alcohols with CCl4 catalyzed by molybdenum compounds
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Mo(CO)6 catalyzed oxidation of alcohols and diols with tetrachloromethane. Primary oxidation products in reaction of alcohols with CCl4 are alkyl hypochlorites, and final products depending on the structure of initial alcohol are aldehydes (as acetals), ketones, chloroketones, and esters.
- Khusnutdinov,Shchadneva,Burangulova,Muslimov,Dzhemilev
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p. 1615 - 1621
(2007/10/03)
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- Indium-catalyzed direct chlorination of alcohols using chlorodimethylsilane-benzil as a selective and mild system
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The InCl3-catalyzed reaction of alcohols with chlorodimethylsilane (HSiMe2Cl) in the presence of benzil gave the corresponding organic chlorides under mild conditions. Benzil significantly changes the reaction course because the reducing product through dehydroxyhydration was obtained in the absence of benzil. The secondary or tertiary alcohols were effectively chlorinated. The substrates bearing acid-sensitive functional groups were also applied to this system. The highly selective chlorination of the tertiary site was observed in the competitive reaction between tertiary and primary alcohols. The highly coordinated hydrosilane generated from benzil and HSiMe2Cl is an important intermediate. Copyright
- Yasuda, Makoto,Yamasaki, Satoshi,Onishi, Yoshiyuki,Baba, Akio
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p. 7186 - 7187
(2007/10/03)
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- FeCl3-activated oxidation of alkanes by [Os(N)O 3]-
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Although the ion [OsVIII(N)(O)3]- is a stable species and is not known to act as an oxidant for organic substrates, it is readily activated by FeCl3 in CH2Cl2/CH 3CO2H to oxidize alkanes efficiently at room temperature. The oxidation can be made catalytic by using 2,6-dichloropyridine N-oxide as the terminal oxidant. The active intermediates in stoichiometric and catalytic oxidation are proposed to be [(O)3OsVIII≡N-Fe III] and [Cl4(O)OsVIII≡N-Fe III], respectively.
- Yiu, Shek-Man,Wu, Zhi-Biao,Mak, Chi-Keung,Lau, Tai-Chu
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p. 14921 - 14929
(2007/10/03)
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- Gas-phase reactions of Cl atoms with propane, n-butane, and isobutane
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Using the relative kinetic method, rate coefficients have been determined for the gas-phase reactions of chlorine atoms with propane, n-butane, and isobutane at total pressure of 100 Torr and the temperature range of 295-469 K. The Cl2 photolysis (λ = 420 nm) was used to generate Cl atoms in the presence of ethane as the reference compound. The experiments have been carried out using GC product analysis and the following rate constant expressions (in cm3 molecule-1 s-1) have been derived: (7.4 ±0.2) × 10-11 exp [-(70 ± 11)/T], Cl + C3H8 → HCl + CH3CH2CH2; (5.1 ± 0.5) × 10-11 exp [(104±32)/T], Cl + C3H8 → HCl + CH3CHCH3; (7.3±0.2) × 10-11 exp [-(68 ± 10)/T], Cl + n-C4H10 → HCl + CH3 CH2CH2CH2; (9.9 ± 2.2) × 10-11 exp [(106 ± 75)/T], Cl + n-C4H10 → HCl + CH3CH2CHCH3; (13.0 ± 1.8) × 10-11 exp [-(104 ± 50)/T], Cl + i-C4H10 → HCl + CH3CHCH3 CH2; (2.9 ± 0.5) × 10-11 exp [(155 ± 58)/T], Cl + i-C4H10 → HCl + CH3CCH3CH3 (all error bars are ±2ρ precision). The studies provide a set of reaction rate constants allowing to determine the contribution of competing hydrogen abstractions from primary, secondary, or tertiary carbon atom in alkane molecule.
- Sarzynski, Dariusz,Sztuba, Barbara
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p. 651 - 658
(2007/10/03)
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- New versatile halogenating reagents for hydroxy groups
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Two new halogenating reagents, viz. allyltriphenoxyphosphonium bromide (ATPB) and allyltriphenoxyphosphonium chloride (ATPC) have been prepared and characterised. These have been evaluated for their potential application in bromination/ chlorination of a variety of compounds including aliphatic straight chain alcohols, branched chain alcohols and also 3′- and 5′-hydroxy groups of deoxyribonucleosides.
- Kumar,Dubey,Singh,Misra
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p. 842 - 845
(2007/10/03)
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- Reactivity of bismuth(III) halides towards alcohols. A tentative to mechanistic investigation
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The reactivity of bismuth(III) halides (BiX3; X=Cl, Br and I) towards a series of alcohols has been investigated. Three different reactions have been studied, namely: halogenation, dehydration and etherification. The behaviour of these bismuth derivatives was found to depend on the nature of the halide bonded to the bismuth atom. Their reactivities can be interpreted on the basis of the Hard and Soft Acids and Bases (HSAB) principle. A mechanism is proposed which involves the formation of a complex of the alcohol with Bi(III).
- Keramane, El Mehdi,Boyer, Bernard,Roque, Jean-Pierre
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p. 1909 - 1916
(2007/10/03)
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- Mild conversion of alcohols to alkyl halides using halide-based ionic liquids at room temperature
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Formula presented Alcohols were efficiently converted to alkyl halides using 1-n-butyl-3-methylylimidazolium halides (ionic liquids) in the presence of Bronsted acids at room temperature. The alkyl halide products were easily isolated from the reaction mixture via simple decantation or extraction, and the 1-n-butyl-3-methylimidazolium cation could be recycled for further uses.
- Ren, Rex X.,Wu, Jeff Xin
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p. 3727 - 3728
(2007/10/03)
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- Process for the preparation of silanes, with a tertiary hydrocarbon group in the a-position relative to the silicon atom
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The invention relates to a process for the preparation of silanes of the general formula 1 by reaction of Grignard reagents of the general formula 2 with silanes of the general formula 3 wherein R denotes C1 - to C10 -hydrocarbon radicals optionally substituted by fluorine, chlorine or cyano radicals, R1, in the α-position relative to the silicon atom, denotes tertiary C4 - to C30 -hydrocarbon radicals optionally substituted by fluorine, chlorine or cyano radicals, X and X1 each denote chlorine, bromine or iodine, m denotes the values 2 or 3 and n denotes the values 1 or 2, in the presence of a transition metal catalyst and an inert, aprotic, and chelating compound.
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- Novel palladium(II) complex containing a chelating anionic N-O ligand: Efficient carbonylation catalyst
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(matrix presented) A novel palladium(II) complex containing chelating anionic pyridine-2-carboxylato and labile tosylato ligands is a highly efficient catalyst for the carbonylation of organic alcohols and olefins to carboxylic acids/esters. Carbonylation of primary, secondary, and tertiary alcohols as well as linear and functionalized terminal olefins was studied. In all cases remarkable activity and selectivity were observed. The catalyst is stable under reaction conditions even in the absence of excess phosphine ligands.
- Jayasree,Seayad,Chaudhari
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p. 203 - 206
(2007/10/03)
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- Thionyl chloride-benzotriazole in methylene chloride: A convenient solution for conversion of alcohols and carboxylic acids expeditiously into alkyl chlorides and acid chlorides by simple titration
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A solution of 1:1 equivalent of thionyl chloride and benzotriazole in dry methylene chloride efficiently transforms alcohols and carboxylic acids into the corresponding alkyl chlorides and acid chlorides respectively at room temperature, with excellent yields by simple titration.
- Chaudhari, Sachin S.,Akamanchi, Krishnacharya G.
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p. 1763 - 1765
(2007/10/03)
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- Method for preparation of tertiary-hydrocarbylsilyl compounds
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A method for the preparation of tertiary-hydrocarbylsilyl compounds. The method comprises contacting a mixture comprising diethylene glycol dibutyl ether, and a Grignard reagent described by formula RMgX with a silicon compound described by formula R1a SiX4-a, where R is a tertiary-hydrocarbyl group comprising four to about 20 carbon atoms, each R1 is an independently selected substituted or unsubstituted monovalent hydrocarbon group comprising one to about 20 carbon atoms, each X is an independently selected halogen atom, and a is an integer with a value of zero to three, in the presence of an effective amount of a copper compound catalyst. The present invention provides a method for making sterically hindered organosilicon intermediates useful in the pharmaceutical industry.
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- BiX3 as an efficient and selective reagent for the halogen exchange reaction
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Bismuth halides are efficient and selective reagents in the halogen exchange reactions carried out under mild conditions. This rapid, high yield reaction proceeds mainly with retention of configuration.
- Boyer, Bernard,Keramane, El Mehdi,Arpin, Severine,Montero, Jean-Louis,Roque, Jean-Pierre
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p. 1971 - 1976
(2007/10/03)
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- BiCl3 : An efficient agent for selective chlorination of alcohols or for halogen exchange reaction
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BiCl3 was found to be an effective reagent for an improved chlorination of alcohols and for a convenient halogen exchange reaction.
- Boyer, Bernard,Keramane, El Mehdi,Montero, Jean-Louis,Roque, Jean-Pierre
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p. 1737 - 1741
(2007/10/03)
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- The versatile behavior of the PdCl2/Et3SiH system. Conversion of alcohols to the corresponding halides and alkanes
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The versatility of the palladium(II) chloride/triethylsilane system has been tested in the transformation of alcohols. The conversion to the corresponding halides and alkanes has been achieved in good yields and in the absence of solvent for a variety of substrates.
- Ferreri,Costantino,Chatgilialoglu,Boukherroub,Manuel
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p. 135 - 137
(2007/10/03)
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- Quaternary ammonium polychlorides as efficient reagents for chlorination of unsaturated compounds
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Chlorination of unsaturated compounds by benzyltributylammonium polychlorides results in higher yields of addition products compared to those obtained with molecular chlorine.
- Zelikman,Tyurin,Smirnov,Zyk
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p. 1541 - 1546
(2007/10/03)
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- Gas-phase substituent effects in highly electron-deficient systems. II. stabilities of 1-aryl-2,2,2-trifluoroethyl cations based on chloride-transfer equilibria
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The relative stabilities of 1-aryl-2,2,2-trifluoroethyl cations were determined based on the chloride ion-transfer equilibria in the gas phase. An application of the Yukawa-Tsuno equation to this substituent effect on the equilibrium constants gave a remarkably larger r+ of 1.53 and a ρ of-10.6, supporting our previous conclusion that the highly electron-deficient benzylic carbocation systems are characterized by extremely high resonance demands. This r+ value, furthermore, conformed a linear relationship between the r+ value and the relative stability of the unsubstituted member of the respective benzylic carbocations, clearly demonstrating a continuous spectrum of varying resonance demands characteristic of the stabilities of carbocations. The π-delocalization of the positive charge into the aryl π-system increases with the destabilization of a carbocation by the α-substituent(s) linked to the central carbon. In addition, the r + value of 1.53 for 1-aryl-2,2,2-trifluoroethyl cations was found to be in complete agreement with that for the solvolysis of 1-aryl-2,2,2- trifluoroethyl tosylates in 80% aq acetone. This reveals that the r+ value observed for this solvolysis must be the intrinsic resonance demand of a highly electron-deficient cationic transition state in the SN 1 ionizing process. The identity of the r+ value was consistent with our previous observation for other benzylic carbocation systems, indicating that the degree of the π-delocalization of the positive charge is identical between the cationic transition state and an intermediate cation for all benzylic systems, which cover a wide range of reactivity and stability of the carbocation. This leads us to the conclusion that the geometry of the transition state in the ionizing process of the SN1 solvolysis, which is a highly endothermic reaction, closely resembles the high-energy product, an intermediate cation.
- Mishima, Masaaki,Inoue, Hiroki,Fujio, Mizue,Tsuno, Yuho
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p. 1163 - 1169
(2007/10/03)
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- tert-Butyl Cation Formation in the Hydrolysis of 2-Methyl-2-propanesulfonyl Chloride, the Simplest Tertiary Alkanesulfonyl Chloride
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Evidence is presented that only significant reaction of 2-methyl-2-propanesulfonyl chloride (1) (a) in water over the pH range 3.5-13.0 or (b) in methanol-chloroform-d is an ionization to the tert-butyl cation (2) and the chlorosulfite anion (ClSO2(-)), followed by further reactions of these species.The organic products include isobutylene (3), tert-butyl chloride (4a), tert-butyl alcohol (4b), and, at high pH, 2-methyl-2-propanesulfinate anion (6) and small amounts of 2-methyl-2-propanesulfonate anion (5).In the presence of barium chloride the rate of hydrolysis of 1 is constant over the pH range 3.5-12.0.
- King, James F.,Lam, Joe Y. L.,Dave, Vinod
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p. 2831 - 2834
(2007/10/02)
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- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
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In the presence of catalytic amount of BiCl3, chloromethylsylanes can be used as chlorinating agents for alcohols, and as chloro-dealkylating agents for silyl ethers and carboxylic and sulfonic esters.The chlorination of (R)-(-)-octan-2-ol and the (R)-(-)-2-mesyloctane by TMSCl gave predominantly the (S)-(+)-2-chlorooctane with inversion of configuration at secondary carbon.According to the class of alcohol, the mechanism involves SN2, SN2' or SN1 processes.This new activation of the Si-Cl bond, probably trough a Si-Cl...BiCl3 interaction gives a hard-soft reagent that can generate a silicenium cation, was also observed with Me3SiBr, BiBr3 and Me3SiI, BiI3 systems.The reaction is also presented as a possible alcoholysis of chlorosilanes, which can lead to siloxanes in non-aqueous conditions. catalysis / halogenation / alcohol / ester / silyl ether / chlorosilane / chlorotrimethylsilane / bromotrimethylsilane / iodotrimethylsilane / siloxane / bismuth (III) halide
- Labrouillere, Mireille,Roux, Christophe Le,Oussaid, Abdelouahad,Gaspard-Iloughmane, Hafida,Dubac, Jacques
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p. 522 - 530
(2007/10/02)
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- C-H bond activation by metal oxo species: Chromyl chloride oxidations of cyclooctane, isobutane, and toluene
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Chromyl chloride, CrO2Cl2, oxidizes cyclooctane, isobutane, and toluene under mild conditions (25-60 °C). The reactions give chlorinated products (chlorocyclooctane, tert-butyl chloride, and benzyl chloride) and a dark chromium-containing precipitate. Hydrolysis of the precipitate yields oxygenated products, such as ketones, aldehydes, chloro ketones, epoxides, and alcohols. Kinetic data show that all of the reactions are first order in CrO2Cl2 and first order in substrate, with no sign of an induction period. Primary isotope effects have been observed for t-d1-isobutane and d8-toluene. The kinetic and mechanistic data indicate that the reactions proceed by initial hydrogen atom transfer from the substrate to CrO2Cl2 The rates of hydrogen atom abstraction by CrO2Cl2 vary in the order cyclohexane ? and ΔS?, indicating a common mechanism for the four substrates. The pathways leading from the initially formed alkyl radicals to the observed products are described. The ability of CrO2Cl2 to abstract a hydrogen atom from alkanes is remarkable, as it is a closed-shell, diamagnetic species, not a radical. It is proposed that the hydrogen atom abstracting ability derives from the strong O-H bond formed on hydrogen atom transfer, in [Cl2(O)Cr(OH)]. The rates of the CrO2Cl2 reactions correlate with rates of hydrogen atom abstraction by oxygen radicals, assuming a CrO-H bond strength of 83 kcal/mol (similar to that in HMnO4-). The implications of this perspective for transition metal mediated hydrogen atom transfer reactions are discussed.
- Cook, Gerald K.,Mayer, James M.
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p. 7139 - 7156
(2007/10/02)
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- The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
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In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
- Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
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p. 217 - 254
(2007/10/02)
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- Infrared Spectra and Relative Stability of Hydrogen Chloride van der Walls Complexes with Various Alkyl Chlorides in Liquefied Noble Gases
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Mid-infrared spectra (4000-400 cm-1) of mixtures of HCl with ethyl-d5, n-propyl, isopropyl-d7, or tert-butyl chloride, dissolved in liquefied argon (95-117 K) and liquefied krypton (122-148 K) have been investigated.In all cases the formation of a 1:1 van der Walls molecule between HCl and the alkyl chloride was observed.At gigher concentrations, a new absorption band, due to a 1:2 complex (RCl)*(HCl)2 was found.The association enthalpy in liquefied argon was determined to be -9.8 +/- 0.6 kJ mol-1 for C2D5Cl*HCl, -10.0 +/- 0.5 kJ mol-1 for gauche-n-C3H7Cl*HCl and -10.8 +/- 0.5 kJ mol-1 for iso-C3D7Cl*HCl.The ΔH0 for the C2D5Cl*HCl species in liquefied krypton was determined to be -9.4 +/- 0.5 kJ mol-1.For the formation of the 1:2 complex from the 1:1 complex and hydrogen chloride, the ΔH0 was determined to be -3.7 +/- 0.4 kJ mol-1 for the ethyl-d5 chloride complex and -4.5 +/- 0.3 kJ mol-1 for the isopropyl-d7 chloride complex.
- Herrebout, W. A.,Veken, B. J. van der
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p. 2836 - 2843
(2007/10/02)
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- Synthesis and flash vacuum thermolysis of 1,2-dihydro-1,2-azaphosphinine 2-oxide-dichlorocarbene adducts
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The reaction of dichlorocarbene with 1,2-dihydro-1,2-azaphophinine 2-oxides follows a regioselective addition on the C5-C6 double bond and yields 3-oxo-2-aza-3-phosphabicycloheptenes 2.The X-ray crystal structure of the major isomer 2aA was determined and shows that the cyclopropane ring and the phenyl group are on opposite sides of the six membered ring.Flash vacuum thermolysis of dihydroazaphosphinine 2-oxide-dichlorocarbene adducts gave 2-oxo-2H-1,2-azaphosphepine 5 and substituted 3-chloropyridines 4.Key Words: 1,2-azaphosphinine 2-oxides / cyclopropanation / X-ray analysis / flash vacuum thermolysis
- Tan, W.H-L. Wai,Bourdieu, C.,Foucaud, A.,Bedel, C.
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- NMR Study of Geminate Recombination of Radicals in Liquid Solution. Complementary Use of SCOTCH and Photo CIDNP Experiments
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A 2D NMR experiment, SCOTCH (spin coherence transfer in chemical reactions), is used to study the kinetics of a geminate radical pair in liquid solution.If an rf pulse is followed by a laser pulse that creates radical pairs transverse nuclear magnetization is transferred from starting material to products.The intensity of this magnetization can be reduced by dephasing processes due to the hyperfine coupling with the free electron in the radical.A theoretical expression for this decrease is given in terms of the lifetime of the radical and the hyperfine coupling constant.Application to the photochemical reaction of pinacolone (methyl t-butylketone) in tetrachloromethane, supplemented with time resolved CIDNP measurements, led to an average lifetime of about 3 ns for the geminate radical pair and 0.4 μs for the escaping radicals. - Key words: NMR / Photochemistry / Radicals / Kinetics
- Pouwels, Petra J. W.,Kaptein, Robert
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p. 143 - 154
(2007/10/02)
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