- LASER-INITIATED FREE-RADICAL CHLORINATION OF PROPANE IN AMORPHOUS THIN FILMS: TEMPERATURE DEPENDENCE FROM 15 TO 77 K
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The free-radical chlorination of propane, deposited as a thin amorphous film, has been investigated at temperatures ranging from 15 to 77 K.Reactions are initiated by pulsed laser photolysis of chlorine molecules at 308 nm.Product yields and branching ration are characterized by Fourier transform infrared absorption spectroscopy.The inherent reactivity of chlorine atoms toward secondary versus primary hydrogens (when corrected for the greater number of primary sites) decreases from 17:1 at 77 K to 2.3:1 at 60 K and below.Over the same temperature range the quantum yield is observed to increase from 0.12+/-0.02 to 0.70+/-0.06.These results reflect the onset of translationally excited (hot) chlorine atom reactions.
- Sedlacek, Arthur J.,Wight, Charles A.
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- Solute-solvent interactions in liquid noble gases as probed by the conformational equilibrium of some 1,2-disubstituted ethanes
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Using variable-temperature infrared spectroscopy, the enthalpy difference between the trans and gauche conformers of 1-chloro-2-fluoroethane, 1,2-dichloroethane, and 1-chloropropane has been determined in the gas phase and in solutions of liquefied krypton and xenon. Using a simple reaction field model, the changes in the enthalpy difference between vapor phase and solution are quantitatively explained as the result of weak dipole-induced dipole interactions appearing between the solute molecules and the surrounding noble gas atoms.
- Herrebout,Van der Veken
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- Chlorine Atom/Benzene System. 1. The Role of the 6-Chlorocyclohexadienyl Radical
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The concept of radical reactivity mediated by solvation has rested mainly on the alteration of Cl. properties by aromatic solvents.For this reason, the full scope of the benzene/Cl. system has been reexamined to evaluate the discription of that system based largely on a ?-complex (solvation).At the present time, the ?-complex description rests narrowly on the assignment of a 490-nm absorption, which, even if correct, could not provide an unambiguous structure assignment.Results are presenteed which described the selectivities in alkane substitutions as a function of the concentrations of both benzene and the alkane.Selectivities increase with decreasing alkane concentrations, reaching a plateau below 0.1 M alkane.The change in selectivity is the result of variable contributions of both a low- and a high-selectivity intermediate, LSI and HSI, respectively.The observed selectivity at a given and is the consequence of a unique / ratio.A range of substrates and their effect of DMB selectivity were studied, and from these results details regarding the chemistry of the HSI were extracted.Several features of the LSI/HSI equilibrating system are realized. (1) Reaction of alkyl radicals with Cl2 in benzene produces the LSI, (2) the LSI does not exhibit the characteristics of free chlorine atom, and (3) at alkane concentrations and , added reagents (T) which react with CCH, such as maleic anhydride (MA) or Cl2, bring about an increase in the LSI/HSI ratio.Low-selectivity hydrogen abstractions (LSI function) are best ascribed to a mixture of chlorine atom and chlorine atom/benzene ?-complex.The chemistry of CCH is as follows: (1) loss of the ipso H to O2 yielding PhCl and HO2., (2) reactions of Cl2 or (3) maleic anhydride with the aromatic nucleus of CCH resulting in additions to the ring, (4) the transfer of Cl to alkenes, and (5) the highly selective retardation of rates of reaction with alkanes producing alkyl radicals, HCl, and benzene.The results of a kinetic analysis, accounting for the effect of , , and CCH trapping agents (T), are presented.For CCH, the following reactivity order is established: maleic anhydride (6) > trans-dichloroethene(5) > 2,3-dimethylbutane (2) > pentane (1) > Cl2 > neopentane ( 2 (27) > 1 .These properties can be rationalized with canonical structures for CCH wherein spin density at carbon, chlorine, and the ipso hydrogen makes contributions to the hybrid.
- Skell, Philip S.,Baxter, Harry N.,Tanko, James M.,Chebolu, Venkatasuryanarayana
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- Formation of C3H6 from the reaction C3H7 + O2 between 450 and 550 K
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The generation of C3H6 from the reaction C3H7 + O2 (1) has been investigated as a function both of temperature (450-550 K) at constant density (5.5 × 1018 molecules/cm3) and of pressure (55-550 Torr) at 490 K. The experiments were carried out by UV irradiation of mixtures of C3H8, Cl2, and O2 to generate propyl radicals. C3H8, C3H6, and C3H7Cl were monitored by gas chromatographic analysis. The propylene yield is 0.7% at 450 K. Based on these measurements and previous data at 298 K, the propylene yield has an apparent activation energy which is less than 2.5 kcal mol-1 below 450 K. Beginning near 450 K, the yield increases rapidly with an apparent activation energy of ~32 kcal mol-1, similar to previous observations on the generation of C2H4 from the reaction C2H5 + O2. At 490 K, the propylene yield from reaction 1 depends inversely on total pressure (YC3H6 ∝ P -0.6) between 55 and 550 Torr, while the overall value of k1 has a much smaller pressure dependence (P0.18). These observations show that above 450 K propylene is formed via reaction 1 through an excited propylperoxy adduct which can be stabilized by collision as was observed at 298 K.
- Kaiser
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- Free radical chlorination of alkanes in supercritical carbon dioxide: The chlorine atom cage effect as a probe for enhanced cage effects in supercritical fluid solvents
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The chlorine atom cage effect was used as a highly sensitive probe for studying the effect of viscosity and the possible role of solvent clusters on cage lifetimes and reactivity for reactions carried out in supercritical fluid solvents. These experiments were conducted in supercritical carbon dioxide (SC-CO2, 40 °C, at various pressures) with parallel experiments in conventional solvents and in the gas phase. The results of these experiments provide no indication of an enhanced cage effect near the critical point in SC-CO2 solvent. The magnitude of the cage effect observed in SC-CO2 at all pressures examined is well within what is anticipated on the basis of extrapolations from conventional solvents.
- Fletcher, Beth,Suleman, N. Kamrudin,Tanko
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- Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
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Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
- Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
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p. 3685 - 3690
(2021/05/31)
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- Catalytic Olefin Hydrosilations Mediated by Ruthenium η3-H2Si σ Complexes of Primary and Secondary Silanes
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Unambiguous examples of η3-H2SiH(R) complexes featuring a terminal Si-H bond have been prepared and examined as possible intermediates in olefin hydrosilation. These species were generated by displacement of the secondary silane ligands in [PhBPPh3]RuH[η3-H2SiMePh] (1b) (PhBPPh3 = PhB(CH2PPh2)3- by primary silanes RSiH3 to generate [PhBPPh3]RuH[η3-H2SiH(R)] (R = Cy (1d), CH2CH2Ph (1e), Trip = 2,4,6-iPr3C6H2 (1f)). Complexes 1d and 1e were characterized in solution, whereas 1f was isolated and studied in detail. Complex 1b is not a competent precatalyst for the hydrosilation of 1-hexene with CySiH3, whereas comparable conditions gave reasonable yields for the selective anti-Markovnikov hydrosilations of Cl3SiCH2CH=CH2 (89%), p-chlorostyrene (73%), and allyl chloride (70%). The 1H NMR spectrum of 1f collected at -30 °C displays a downfield signal (δ = 8.26 ppm) for the terminal Si-H bond that suggests electronic similarities between 1f and cationic silylene dihydrides [Cp?(iPr3P)Ru(H)2=SiH(R)]+ that mediate olefin hydrosilations via the direct insertion of the C=C bond into the terminal Si-H bond. However, further mechanistic considerations, including results on the hydrosilation of p-chlorostyrene with the secondary silane Et2SiH2 and [PhBPPh3]RuH[η3-H2SiEt2] (1a) as the catalyst, indicate that an insertion mechanism involving a Ru-H (rather than a Si-H) group is possible. DFT investigations of the hydrosilation of several olefins with CySiH3 using 1d as the catalyst reveal a preferred pathway involving olefin insertion into a Ru-H bond followed by migration of the resulting alkyl group to the silicon atom of an η3-H2SiH(Cy) ligand. The latter process occurs via an unusual transition state in which a Ru-H-Si linkage acts as a pivot point to facilitate a Si-H bond cleavage/Si-C bond formation step that is otherwise similar to those involving the kite-shaped four-center transition states of σ-bond metathesis. Direct insertion into the Si-H bond is the next lowest accessible pathway.
- Lipke, Mark C.,Poradowski, Marie-Noelle,Raynaud, Christophe,Eisenstein, Odile,Tilley, T. Don
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p. 11513 - 11523
(2018/11/23)
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- Facile one-step synthesis of palladium tellurium alloy nanorods
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A palladium-tellurium binary alloy nanomaterial was synthesized by a one-pot reaction of bis(4-methoxyphenyltelluro)methane [(4-CH3O-C6H4Te)2CH2](1) and allylpalladium (II)chloride dimer [(η3-C3H5)2Pd2(μ-Cl2)] (2) in 1:1 ratio using methylene chloride as solvent at ambient conditions. In addition to the Pd20Te7 alloy nanomaterial (3) generated, a palliadum (II) tellurolate complex [PdC1(μ-TeC6H4-OCH3)Te(C6H4-OCH3)2]2 (6), and other organic and organotellurim compounds were isolated as byproducts using column chromatography. The palladium-tellurium binary alloy nanomaterial and other byproducts from the reaction were characterized by powder X-ray diffraction (PXRD), NMR, GC-MS, transmission electron microscopy (TEM), and single crystal X-ray diffractions (XRD) methods. The palladium-tellurium binary alloy nanomaterial was obtained as single-phase Pd20Te7 nanorods, under mild conditions. TEM results indicated that the nanorods are less than 15 nm in diameter and range from 40 to 200 nm in length. A nanomaterial mixture was isolated with two binary-phases Pd20Te7 and Pd10Te3 when benzene was used as solvent. Compound 6 was successfully tested for catalytic activity for the Heck Reaction and produced a mixture of PdTe2 with Pd13Te3 nanomaterials as byproducts.
- Mariappan, Kadarkaraisamy,Varapragasam, Shelton J.P.,Hansen, Matthew R.,Rasalingam, Shivatharsiny,Alaparthi, Madhubabu,Sykes, Andrew G.
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p. 251 - 256
(2018/05/23)
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- Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
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Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
- Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
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supporting information
p. 6940 - 6944
(2018/05/14)
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- Propane chlorination over ruthenium oxychloride catalysts
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The gas-phase chlorination of propane over different catalysts, including those containing ruthenium oxychlorides as the active component, has been investigated. The propylene and chlorine-containing product formation selectivities in propane chlorination at 150-450°C in a fixed-bed flow reactor have been determined.
- Testova,Shalygin,Maksimov,Paukshtis,Parmon
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p. 428 - 433
(2015/08/04)
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- Partial oxidation of light alkanes by periodate and chloride salts
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The efficient and selective partial oxidation of light alkanes using potassium periodate and potassium chloride is reported. Yields of methane functionalization in trifluoroacetic acid reach >40% with high selectivity for methyl trifluoroacetate. Periodat
- Kalman, Steven E.,Munz, Dominik,Fortman, George C.,Boaz, Nicholas C.,Groves, John T.,Gunnoe, T. Brent
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supporting information
p. 5294 - 5298
(2015/03/30)
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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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- PROCESS FOR THE PRODUCTION OF ALKENES AND/OR AROMATIC COMPOUNDS
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Processes for the production of alkenes are provided. The processes make use of methane as a low cost starting material.
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Paragraph 0050-0052
(2013/07/05)
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- Diastereoselective synthesis of new dialkylphosphorylhydrazones
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A series of 22 dialkylphosphorylydrazones (dialkyl ester, N′-[(1E)-(R1 phenyl)methylene]-phosphorohydrazidic acid), 20 of them new, along with three new N,N′-bis (diisobutylphosphorylthioamide)diamines (bis-[diisobutyl ester), N-thioxomethylene]-, diamine)phosphora-midic acid, were prepared and characterized by IR, 1H NMR, 13C NMR, 31P NMR, and mass spectrometry. The analysis of 1H NMR, 13C NMR, 31P NMR, and NOE spectra confirmed the observation of the single diastereoisomer E in the synthesis of dialkylphosphorylydrazones. The results of a molecular modeling study performed in order to investigate the mechanism of the synthesis of dialkylphosphorylydrazones are in agreement with the experimental results, i.e., the favored formation of diastereoisomer E over Z.
- Rodrigues, Janaina Marques,Sant'anna, Carlos Mauricio R.,Rumjanek, Victor Marcos,Dacosta, Joao Batista Neves
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experimental part
p. 40 - 56
(2010/04/26)
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- Nickel complexes of a pincer amidobis(amine) ligand: Synthesis, structure, and activity in stoichiometric and catalytic C-C bond-forming reactions of alkyl halides
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The synthesis, properties, and reactivity of nickel(II) complexes of a newly developed pincer amidobis(amine) ligand (McNN2) are described. Neutral or cationic complexes [(MeNN2)NiX] (X = OTf (6), OC(O)CH3 (7), CH3CN (8), OMe (9)) were prepared by salt metathesis or chloride abstraction from the previously reported [( MeNN2)NiCl] (1). The Lewis acidity of the {( McNN2)Ni) fragment was measured by the 1H NMR chemical shift of the coordinated CH3CN molecule in 8. Electrochemical measurements on 1 and 8 indicate that the electron-donating properties of NN2 are similar to those of the analogous amidobis(phosphine) (pnp) ligands. The solid-state structures of 6-8 were determined and compared to those of 1 and [(MeNN2)NiEt] (3). In all complexes, the MeNN2 ligand coordinates to the NiII ion in a mer fashion, and the square-planar coordination sphere of the metal is completed by an additional donor. The coordination chemistry of MeNN 2 thus resembles that of other three-dentate pincer ligands, for example, pnp and arylbis(amine) (ncn). Reactions of 2 with alkyl monohalides, dichlorides, and trichlorides were investigated. Selective C-C bond formation was observed in many cases. Based on these reactions, efficient Kumada-Corriu-Tamao coupling of unactivated alkyl halides and alkyl Grignard reagents with 1 as the precatalyst was developed. Good yields were obtained for the coupling of primary and secondary iodides and bromides. Double C-C coupling of CH2Cl2 with alkyl Grignard reagents by 1 was also realized. The scope and limitations of these transformations were studied. Evidence was found for a radical pathway in Ni-catalyzed C-C cross-coupling reactions, which involves NiIl alkyl intermediates.
- Vechorkin, Oleg,Csok, Zsolt,Scopelliti, Rosario,Hu, Xile
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experimental part
p. 3889 - 3899
(2009/12/26)
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- A domino three-component condensation of ortho-haloacetophenones with urea or amines: a novel one-pot synthesis of halogen-substituted quinolines
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Halogen-substituted quinolines have been synthesized in good yields by the condensation and cyclization of two molecules of ortho-haloacetophenones with urea or primary amines. The formation of halogen-substituted quinolines takes place through the unexpe
- Qi, Chuanmei,Zheng, Qingwei,Hua, Ruimao
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body text
p. 1316 - 1320
(2009/05/07)
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- Transformation of tertiary amines into alkylating reagents by treatment with 2-chloro-4,6-dimethoxy-1,3,5-triazine. A synthetic application of side-reaction accompanying coupling by means of 4-(4,6-dimethoxy-[1,3,5] triazin-2-yl)-4-methyl-morpholin-4-ium chloride (DMTMM)
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Mild reaction conditions are described for the preparation of a number of alkyl chlorides and 2-dialkyl(aryl)amino-4,6-dirnethoxy-1,3,5-triazines by dealkylation of quaternary triazinylammonium chlorides formed as reactive intermediates in reaction of tertiary amines with 2-chloro-4,6-dimethoxy-1,3,5- triazine. The high selectivity of substitution was observed within the reactivity order of the alkyl groups: benzyl ~ allyl > methyl > n-alkyl. Studies on dealkylation of S-(-)-J-dimethyl-(1-phenylethyl)amine to R-(+)-1-chloro-1-phenylethane revealed that reaction proceeded with an inversion of configuration on the carbon atom as may be expected for SN2 type substitution. The scope of reaction was extended by exchange of anion in quaternary triazinylammonium chlorides with 1-, SCN-, C6H5O-, CH3COO- followed by N-dealkylation step.
- Kolesinska,Kaminski
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experimental part
p. 2115 - 2123
(2009/04/07)
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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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- Kinetics of the reactions of C2H5, n-C 3H7, and n-C4H9 radicals with Cl2 at the temperature range 190-360 K
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The kinetics of the C2H5 + Cl2, n-C 3H7 + Cl2, and n-C4H9 + Cl2 reactions has been studied at temperatures between 190 and 360 K using laser photolysis/photoionization mass spectrometry. Decays of radical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficients under pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independent of the helium bath gas pressure within the experimental range (0.5-5 Torr) and are found to depend on the temperature as follows (ranges are given in parenthesis): k(C 2H5+ Cl2) = (1.45 ± 0.04) × 10-11 (T/300K)-1-73±0.09 cm3 molecule-1 s-1 (190-359 K), k(n-C3H7 + Cl2) = (1.88 ± 0.06) × 10-11 (T/300 K)-1.57 ± 0.14cm3 molecule-1 s -1 (204-363 K), and k(n-C4H9 + Cl2) = (2.21 ± 0.07) × 10-11 (T/300 K) -238 ± 0.14 cm3 molecule-1 s -1 (202-359 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are ±20%. Current results are generally in good agreement with previous experiments. However, one former measurement for the bimolecular rate coefficient of C2H5 + Cl2 reaction, derived at 298 K using the very low pressure reactor method, is significantly lower than obtained in this work and in previous determinations.
- Eskola, Arkke I.,Lozovsky, Vladimir A.,Timonen, Raimo S.
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p. 614 - 619
(2008/09/17)
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- PROCESS FOR MAKING HALOORGANOALKOXYSILANES
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A haloorganoalkoxysilane is prepared by reacting an olefinic halide with an alkoxysilane in which the alkoxy group(s) contain at least two carbon atoms in a reaction medium to which has been added a catalytically effective amount of ruthenium-containing catalyst and a reaction-promoting effective amount of an electron-donating aromatic compound promoter. The process can be used to prepare, inter alia, chloropropyltriethoxysilane, which is a key intermediate in the manufacture of silane coupling agents.
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Page/Page column 11-12; 18
(2008/06/13)
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- Process for making haloorganoalkoxysilanes
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A haloorganoalkoxysilane is prepared by reacting an olefinic halide with an alkoxysilane in which the alkoxy group(s) contain at least two carbon atoms in a reaction medium to which has been added a catalytically effective amount of ruthenium-containing catalyst and a reaction-promoting effective amount of an electron-donating aromatic compound promoter. The process can be used to prepare, inter alia, chloropropyltriethoxysilane, which is a key intermediate in the manufacture of silane coupling agents.
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- Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents
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Alkoxy-λ6-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, ptoluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ6-sulfanenitriles showed an opposite trend to the usual SN2 character, i.e. Me (la), Pr (1b), and Bu (1d) ? i-Pr (1c). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ6-sulfanenitrile, was found to undergo an SN2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield.
- Hao, Wei,Fujii, Takayoshi,Dong, Tiaoling,Wakai, Youko,Yoshimura, Toshiaki
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p. 193 - 198
(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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- Oxidative alkoxylation of zinc phosphide in alcoholic solutions of copper(II) chloride
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Oxidative alkoxylation of Zn3P2 with the formation of valuable phosphoric and phosphorous acid esters occurred at a high rate and with a high selectivity in alcoholic solutions of CuCl2 under the action of oxygen at 30-60°C. Depending on the nature of the alcohol, two products were formed, namely, trialkyl phosphates (RO)3PO and dialkyl phosphites (RO)2HPO. Water favored the formation of dialkyl phosphates (RO)2(HO)PO. The kinetics and mechanism of the new catalytic reaction were studied, and the optimal conditions for conducting this reaction were found. The reaction proceeded in a topochemical mode by a separate redox mechanism.
- Dorfman,Ibraimova,Polimbetova
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- Compositions and methods using platinum compounds for nucleic acid labeling
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The invention relates to novel platinum-based compounds for labeling biomolecules. Platinum based labeling compounds according to the invention irreversibly attach to a target biomolecule via coordination of a platinum (II) metal center with N or S atoms on the target biomolecule. The invention relates to the novel compounds themselves, methods of making the platinum-based labeling compounds, probes labeled with such compounds, methods of making such labeled probes, and kits comprising the novel platinum-based labeling compounds and/or probes labeled with them. The invention also relates to methods of using probes labeled with platinum-based labeling compounds of the invention, particularly array and microarray hybridization methods.
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- Generation of alkyl hypochlorites in oxidation of alcohols with carbon tetrachloride catalyzed by vanadium and manganese compounds
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Primary alcohols and diols with various structures were subjected to transformations into esters, aldehydes, ketones, and lactones under the action of carbon tetrachloride in the presence of manganese compounds (MnCl 2, MnO2, Mn(OAc)2, Mn(acac)3) and vanadium compounds (VCl5, V2O5, VO(acac) 2) as catalysts. These transformation proceeded with the involvement of alkyl hypochlorites, which were generated in the course of oxidation of alcohols with carbon tetrachloride catalyzed by manganese or vanadium compounds. The optimum molar ratios between the catalyst and reagents were determined, and the reaction conditions for the highly selective synthesis of esters, aldehydes, ketones, and lactones from alcohols were found.
- Khusnutdinov,Shchadneva,Baiguzina,Lavrentieva,Dzhemilev
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p. 2074 - 2079
(2007/10/03)
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- Should anionised benzylic sulfones be considered as carbenoids?
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Na·Hg reduction of benzyl sulfones 1c-e in aprotic solvent conditions affords stilbenes 4c-e, an olefination process best explained by assuming that the corresponding sulfone carbanion, which was formed under these conditions, is decomposed into a carbene species.
- Jolivet,Uguen
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p. 7907 - 7911
(2007/10/03)
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- New aspect of nucleophilic reactivity of tertiary phosphine oxides. R3PO-POCl3 binary system
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The reaction of tertiary phosphine oxides with phosphorus oxychloride was found to give triorganylphosphonium dichlorophosphates R3PCl+PO2Cl-2 rather than phosphorylphosphonium salts R3P · OPOCl2. Mixtures of the reagents, called binary system, possess a considerable synthetic potential. They are capable of converting alcohols to the corresponding alkyl chlorides.
- Kazantseva,Timokhin,Rokhin,Blazhev,Golubin,Rybakova
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p. 1233 - 1235
(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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- Reaction of Trichloro(o-phenylenedioxy)phosphorane with 1,2-Alkadienylphosphonates
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Trichloro(o-phenylenedioxy)phosphorane reacts with 1,2-alkadienylphosphonates with selective replacement of the alkoxy group in the phosphinoyl moiety, yielding the corresponding 1,2-alkadienylchlorophosphonates and o-phenylene chlorophosphate.
- Khusainova,Garipova,Zyablikova,Cherkasov,Pudovik
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p. 339 - 342
(2007/10/03)
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- Hydrolytic Etherification of Phenyltrichlorosilane and Structure of Reaction Products
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Hydrolytic etherification of phenyltrichlorosilane by C1-C4 primary alcohols was studied. The effect of the concentration and nature of alcohol on the structure and properties of oligomeric polyphenyl-alkoxysilanes were examined.
- Kuz'menko, N. Ya.
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p. 516 - 522
(2007/10/03)
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- Kinetics and mechanisms of the reactions of chlorine atoms with ethane, propane, and n-butane
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Absolute (flash photolysis) and relative (FTIR-smog and GC) rate techniques were used to study the gas-phase reactions of Cl atoms with ethane (k1), propane (k3), and n-butane (k2). Experiments performed at 298-540 K give k2÷k1=(2.0±0.1)exp((183±20)÷T). At 296 K the reaction of Cl atoms with propane yields of 43 % 1-propyl and 57 % 2-propyl radicals, while the reaction of Cl atoms with n-butane produces 29% 1-butyl and 71% 2-butyl radicals. Butyl radicals were found to react with Cl2 with rates which are 3 times greater than the corresponding reactions with O2.
- Tyndall,Orlando,Wallington,Dill,Kaiser
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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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- Reinvestigation of the SNi Reaction. The Ionization of Chlorosulfites
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The decomposition of alkyl chlorosulfites (ROSOCl) has been investigated both computationally and experimentally.Semiempirical (AM1 and PM3) as well as ab initio (HF/3-21G(*), HF/6-31G*, and MP2(full)/6-31G*//MP2(full)/6-31G*) methods were employed, and the results were confirmed experimentally by NMR spectroscopy.The computations indicated that certain alkyl sulfinyl cations (ROSO(1+)) are stable and might be involved in the decomposition of chlorosulfites.Detection of these ions by 1H and 13C NMR spectroscopy in polar solvents such as acetone-d6 and acetonitrile-d3 as well as kinetic studies allowed important conclusions to be drawn about the mechanistic details of the SNi reaction.We conclude that primary alkyl chlorosulfites ionize to yield a sulfinyl cation (ROSO(1+)) and Cl(1-), whereas tertiary chlorosulfites preferentially give a carbenium ion and a chlorosulfinyl anion (OSOCl(1-)) The generation of these ion pairs is facilitated in polar solvents where the rates of decomposition of chlorosulfites are largely accelerated.The decomposition of neopentyl chlorosulfite without rearrangement and the substitution at the bridgehead position of 7,7-dimethylbicycloheptyl 1-chlorosulfite show that the loss of SO2 from ROSO(1+) must be accompanied by the attack of the chloride ion from the front side.
- Schreiner, Peter R.,Rague Schleyer, Paul von,Hill, Richard K.
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p. 2822 - 2829
(2007/10/02)
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- DITHIOACETALS OF POLYFLUORINATED ALIPHATIC ALDEHYDES AND THE SYNTHESIS OF 1,1-DICHLOROPOLYFLUOROALKANESULFENYL CHLORIDES
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In reaction with aliphatic and aromatic thiols polyfluorinated aliphatic aldehydes form dithioacetals.The latter are intermediates in the synthesis of 1,1-dichloropolyfluoroalkanesulfenyl chlorides, fluorine-containing ketene dithioacetals, and monothio- and dithiopolyfluoroalkanecarboxylic acids.
- Markovskii, L. N.,Slyusarenko, E. I.,Timoshenko, V. M.,Kaminskaya, E. I.,Kirilenko, A. G.,Shermolovich, Yu. G.
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- SYNTHESIS AND CHEMISTRY OF DIALKYL- AND DIARYLTRICHLOROMETHYLPHOSPHINES
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Dialkyltrichloromethylphosphines; diphenyltrichloro-methylphosphine; P-chloro-dialkyl-dichloromethylenephosphoranes; P-chloro-diphenyl-dichloromethylenephophorane; phosphonium salt; chlorination; dehydration; condensation.
- Majewski, Piotr
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p. 185 - 194
(2007/10/02)
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- Process for the preparation of phenylalanine n-propyl ester hydrochloride
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In order to prepare phenylalanine n-propyl ester hydrochloride, phenylalanine hydrochloride is reacted with n-propanol in the molar ration 1: (5 to 20) at temperatures from 80° to 110° C., preferably 85° to 105° C., at pressures from 0.1 to 1.5 bar in the presence of 0.1 to 0.75 mole of HCl/mole of phenylalanine hydrochloride as catalyst and in the presence of water entrainer, a concentration of water entrainer of 20 to 50% by weight being maintained in the reaction mixture.
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- Electron Transfer versus Energy Transfer in the Reactions of 2E Cr(bpy)33+ with Organochromium and Organocobalt Complexes
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The pentaaquoorganochromium complexes, (H2O)5CrR2+, and a series of organocobalt complexes, (H2O)(aneN4)CoR2+ (aneN4=1,4,8,11-tetraazacyclotetradecane), quench the luminescence of 2E Cr(bpy)33+.The kinetic trend in the reactions of (H2O)5CrR2+ at 25 deg C (R, 10-7 kCr/M-1 s-1: CH3, ca. 0.15; C2H5, 1.9; 2-C3H7, 32; CH2C6H5, 157; CH2OCH3, 8.5; CH2Cl, ca. 0.1) is that expected for outer-sphere electron transfer to 2E Cr(bpy)33+.The organocobalt complexes are generally more reactive, but the reactivity pattern (R, 10-7 kCo/M-1 s-1: CH3, 9.4; C2H5 13; 1-C3H7 2.7; CH2OCH3 5.2; CH2Cl 22; CH2Br 35) is clearly distinct from that observed in the organochromium series.The oxidation of the organocobalt complexes by Ru(bpy)33+ shows a pattern that is typical of outer-sphere electron transfer (R k/M-1: CH3 16.0; 1-C3H7, 442; CH2OCH3 649; CH2Cl, 3+ thus signals a major change in mechanism.It is proposed that the cobalt complexes react by energy transfer to yield and Cr(bpy)33+.The relaxation of to the ground state takes place in competition with the unimolecular homolysis to yield Co(aneN4)(H2O)n2+ and R..The semiquantitatively measured yields of Cr(bpy)32+ are consistent with these assignments, as are literature data that show efficient energy transfer quenching of by inorganic cobalt(III) macrocycles but not by (H2O)5CrIIIX complexes.
- Bakac, Andreja,Espenson, James H.
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p. 3453 - 3457
(2007/10/02)
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- Laser-Initiated Chain Reactions of Chlorine with Propane and Cyclopropane in Amorphous Films at 77 K
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Free radical reactions of chlorine with propane and cyclopropane deposited as amorphous thin films at 77 K have been investigated.Reactions are initiated by pulsed laser photolysis of the chlorine molecules at 308 nm.Product yields and branching ratios have been determined by Fourier transform infrared absorption spectroscopy of the films following irradiation.The Cl2/propane system is characterized by low product yields consistent with a local radical recombination mechanism.However, the Cl2/cyclopropane reaction proceeds via a true chain reaction mechanism involving ring opening of the hydrocarbon.The dominant product of the reaction is the anti,anti conformer of 1,3-dichloropropane.Product yields have been determined as a function of the mole fraction of chlorine in binary mixtures of the reagents.The results are consistent with a simple statistical model for free radical trapping in nonreactive sites within the amorphous films.
- Sedlacek, Arthur J.,Mansueto, Edward S.,Wight, Charles A.
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p. 6223 - 6229
(2007/10/02)
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- Continuous Conversion of Alcohols into Alkyl Halides by Gas-Liquid Phase-Transfer Catalysis (G.L.-P.T.C)
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A solution of a primary alcohol (propan-1-ol, butan-1-ol, and pentan-1-ol) in an aqueous halogen acid (hydrochloric or hydrobromic acid) when passed in the gaseous state over a solid porous bed (silica gel) supporting a catalyst, affords the corresponding alkyl halide.The reagent mixture is introduced continuously into a column maintained at 170 deg C and the product is collected at the outlet.Since the process is catalytic, the bed is not consumed during the reaction.The reaction by-products depend on the type of catalyst used: Lewis acids (ZnCl2, AlCl3) lead to large quantities of alkenes and isomeric halides, while under typical g.l.- p.t.c. conditions, with a phosphonium salt as the catalyst, only the corresponding dialkyl ether, in addition to the primary alkyl halide, is obtained.The yield of the ether can be reduced progessively to zero by increasing the contact time between the reaction mixture and the catalytic bed.
- Tundo, Pietro,Venturello, Paolo,Angeletti, Enrico
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p. 2157 - 2158
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 1. PROTONOLYSIS OF TRIALKYLBORANES. A CONVENIENT NON-CATALYTIC CONVERSION OF ALKENES INTO SATURATED COMPOUNDS via HYDROBORATION-PROTONOLYSIS
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The protonolysis of trialkylboranes with carboxylic acids proceeds very rapidly for the first group, somewhat slower for the second, but requires elevated temperatures for removal of the third.A close examination of the protonolysis of representative symmetrical, as well as mixed trialkylboranes, reveals that the steric requirements of the alkyl groups attached to boron play an important role in the rate.Secondary alkyl groups protonolyze less readily than primary alkyl groups.More hindered alkyl groups are still more resistant.Since the hydroboration-protonolysis sequence involves relatively mild conditions, this procedure can be applied for hydrogenating olefinic derivatives containing labile groups, such as active sulfur, halogen and nitrogen functionalities.The stereochemistry of protonolysis has been established via deuteroboration of norbornene and deuterolysis of the product.It is evident that protonolysis proceeds with retention of configuration at the migrating carbon.Partially alkylated boranes can be used for hydroboration-protonolysis with improved regioselectivity.Subsequent protonolysis of the resulting mixed trialkylboranes provides the desired alkanes in good yields.Products sensitive to the action of hot acetic acid offer difficulties.For example, when this procedure was applied to the preparation of 1-menthene from d-limonene, the product was racemic.
- Brown, Herbert C.,Murray, Kenneth J.
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p. 5497 - 5504
(2007/10/02)
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- SN2 Reactions in the Gas Phase. Temperature Dependence of the Rate Constants and Energies of the Transition States. Comparison with Solution
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The rate constants for the gas-phase reactions Cl- + RBr = ClR + Br-, where R = Me, Et, n-Bu, i-Pr, and i-Bu, were determined for temperatures between 25 and 390 deg C with a pulsed electron beam high ion source pressure mass spectrometer.The rate constants for Me decreased with an increase of temperature (negative temperature dependence).Et and n-Bu had almost no temperature dependence while i-Pr and i-Bu had positive temperature dependence.An analysis of the data on the basis of theory provides approximate values for ΔE0, the energy of the transition state relative to the energy of the reactants.These ΔE0 values are as follows: Me, -2.5; Et, 0.8; n-Bu, -0.5; i-Pr, +5.1; i-Bu, +5.7 kcal/mol.The δΔE0 are compared with relative activation energies: δEa in solution (C.K.Ingold and A.J.Parker) and calculated strain energies δΔEstrain due to steric repulsions in the transition state (C.K.Ingold and D.F.DeTar).An approximate agreement between the three sets of data is found.This finding supports the assumption of Ingold that steric effects in the transition state dominate the relative rates of this reaction series.The temperature dependence of the rate constants in the gas phase is of interest to ion-molecule reaction theory.It provides a graphic demonstration for the effect of the central barrier in the double-well reaction coordinate.When ΔE0 is negative, negative temperature dependence is observed.When -ΔE0 is small (Me, n-Bu) the reaction proceeds with chemical activation at the very low pressures used in ion cyclotron resonance but with near Boltzmann transition-state distribution at the higher pressures used in high-pressure mass spectrometry.When ΔE0 is positive, the reaction proceeds with positive temperature dependence and boltzmann transition-state distribution.
- Caldwell, Gary,Magnera, Tom F.,Kebarle, Paul
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p. 959 - 966
(2007/10/02)
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- Catalytic Interconversion of Alkyl Halides by Gas-liquid Phase-transfer Catalysis
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High halogen exchange conversions are achieved when a gaseous mixture of alkyl halides (chlorides, bromides, iodides) is passed over a solid bed consisting of porous inorganic supports bearing a phase-transfer catalyst under gas-liquid phase-transfer catalysis (g.l.-p.t.c.) conditions.The process is catalytic since the bed undergoes no changes once it reaches operating conditions.For example, a methylene dichloride and bromoethane mixture is converted into all the halogen-exchange products, and their statistical distribution at equilibrium depends on the original ratio of the halogens in the organic reagents.Catalytic activity is high: 200 ml of such a mixture can be converted in 1 h by passage through 200 g of alumina coated with 10 percent tetrabutylphosphonium bromide.The catalytic process is promoted by the halide anions present as Q(1+)X(1-) in the liquid phase constituted by the molten catalyst and as Na(1+)X(1-) in the solid inorganic support; the halide anions partition themselves between the liquid and solid phases as a function of their respective affinities.This catalysis depends on the diffusion, partition, and adsorption of the alkyl halides between the gaseous, liquid, and solid phases, as well as on their intrinsic nucleophilic reactivity.Mechanistic aspects and industrial applicability are discussed.
- Tundo, Pietro,Venturello, Paolo,Angeletti, Enrico
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p. 485 - 492
(2007/10/02)
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