- Application of Natural Abundance 2H NMR. Simultaneous Measurement of Primary and Secondary Kinetic Deuterium Isotope Effects
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Internal and external reference methods are introduced for the study of kinetic deuterium isotope effects (KDIEs) by natural abundance 2H NMR.These methods take account of both inter- and intra-molecular competitive reactions of fully protonated and naturally monodeuteriated molecules of the substrate in the reaction.Specially deuteriated compounds are not necessary using these methods.These techniques have further advantages over other methods; for example, primary and secondary KDIEs of different types can be simultaneously.The methodology is summarized and examples of its application are presented.KEY WORDS: Natural Abundance 2H NMR Isotope effects
- Zhang, Ben-Li
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Read Online
- Chlorine-catalysed Pyrolysis of 1,2-Dichloroethane. Part 2.-Unimolecular Decomposition of the 1,2-Dichloroethyl Radical and its Reverse Reaction
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Fall-off curves for the unimolecular rate constant k2 of the reaction have been calculated by the Forst and RRKM methods and compared with the experimental results reported in Part 1 and by Huybrechts et al.The Forst calculations can be fitted to the Part 1 results, but then predict K2(infinite) values that lie below the experimental results of Huybrechts et al. which refer to lower temperatures and higher pressures.In contrast RRKM calculations using higher Arrhenius parameters give fall-off curves that are compatible with all available experimental data.The preferred RRKM models without allowance for the centrifugal effect have E2(infinite) ca 19.6 kcal/mol (82 kJ 1/mol) and A2(infinite) ca 1E14.0 s-1.When a reasonable centrifugal effect is allowed for the early transition state (I+/I ca 2) the preferred models have E2 ca 20.0 kcal 1/mol (84 kJ 1/mol) and A2(infinite) ca 1E14.3 s-1.Our experimental evaluations of k(p)-2 are used in conjunction with earlier experimental results and RRKM-based calculations for the reverse reaction to evaluate A-2(infinite) and E-2(infinite).
- Ashmore, Philip G.,Owen, Anthony J.,Robinson, Peter J.
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Read Online
- PROCESS FOR PRODUCING 1,1,2-TRICHLOROETHANE
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The present disclosure relates to a process for producing 1,1,2-trichloroethane. According to the present disclosure, a process for producing 1,1,2-trichloroethane with a simplified equipment and a high reaction yield is provided.
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Paragraph 0049-0054
(2020/12/19)
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- Method for synthesizing 1,2-difluoroethane and 1,1,2-trifluoroethane
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The invention relates to a method for synthesizing 1,2-difluoroethane and 1,1,2-trifluoroethane, belonging to the field of organic chemical synthesis. The method for synthesizing 1,2-difluoroethane and 1,1,2-trifluoroethane is characterized in that ethylene (with a molecular formula of CH2=CH2) and chlorine (with a molecular formula of Cl2) are heated under the action of a catalyst to generate a mixture of 1,2-dichloroethane and 1,1,2-trichloroethane, and the mixture and hydrogen fluoride (with a molecular formula HF) are heated under the action of a fluorination catalyst to generate 1,2-difluoroethane and 1,1,2-trifluoroethane. According to the method, raw materials are low in process and convenient to obtain; product separation and purification are simple; industrial production is easy;and industrial three-waste generation amount is low.
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Paragraph 0022; 0024-0026; 0033-0034; 0037-0039; 0046-0047
(2020/05/30)
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- Rational design of CrOx/LaSrMnCoO6 composite catalysts with superior chlorine tolerance and stability for 1,2-dichloroethane deep destruction
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1,2-dichloroethane (1,2-DCE) is a representative industrial chlorinated volatile organic compound (CVOC) making great hazardous to the environment and human health. In this work, LaSrMnCoO6 (LSMC) double perovskite-type materials with high thermal stability and coke resistance in 1,2-DCE oxidation were prepared by a facile sol-gel method. Based on this, a series of CrOx/LaSrMnCoO6 catalysts (Cr/LSMC, CrOx loading = 5 to 20 wt.%) which combine the merits of CrOx (high activity and chlorine tolerance) and LaSrMnCoO6 were synthesized and adopted in deep oxidation of 1,2-DCE for the first time. As expected, obvious synergistic effects between CrOx and LSMC on 1,2-DCE destruction were observed. Amongst, 10 wt.% CrOx/LaSrMnCoO6 (10Cr/LSMC) shows the best catalytic activity with 90% of 1,2-DCE destructed at 400 °C. Furthermore, the outstanding catalytic durability and water resistance of 10Cr/LSMC in 1,2-DCE oxidation were also demonstrated. In addition to this, the reaction pathway of 1,2-DCE decomposition over Cr/LSMC materials was discussed based on the results of online product analysis. We found that the enhanced catalytic performance of Cr/LSMC materials can be reasonably attributed to their high reducibility, excellent 1,2-DCE adsorption capability, and large amounts of surface active lattice oxygen species. It can be anticipated that the Cr/LSMC catalysts are promising materials for CVOC elimination and the results from this work could also provide some new insights into the design of catalysts for CVOC efficient destruction.
- Tian, Mingjiao,Jian, Yanfei,Ma, Mudi,He, Chi,Chen, Changwei,Liu, Chao,Shi, Jian-Wen
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- PROCESS FOR THE PRODUCTION OF CHLORINATED METHANES
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The present invention provides processes for the production of chlorinated methanes via the direct chlorination of methane. The processes include a dehydrochlorination and/or chlorination step that converts up to 100% of the higher chlorinated alkanes in a process stream from the methane chlorination reaction into more highly chlorinated alkanes. These more highly chlorinated alkanes can be easily removed from the process stream. The use of a cost effective feedstream of crude methane is thus rendered possible, without additional capital expenditure for the sophisticated separation equipment required to separate ethane and other hydrocarbon components from the methane feed.
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Paragraph 0062; 0063
(2017/04/11)
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- Low-temperature catalytic oxidation of vinyl chloride over Ru modified Co3O4 catalysts
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Ruthenium modified cobalt oxides were prepared by (1) impregnating ruthenium chloride hydrate on cobalt oxides, Ru-supported catalysts (Ru/Co3O4), and (2) Ru-doped catalysts (Ru-Co3O4) where the ruthenium ions were added to the precursor solution, by a one-step sol-gel method with cobalt nitrate. The physicochemical properties of the catalysts were characterized by ICP, BET, XRD, HR-TEM, TPR, and XPS analysis. The effects of ruthenium were studied for the total oxidation of vinyl chloride. This Ru modifier was observed to enhance oxygenate formation. The different preparation methods made contributions to the different amounts of Ru4+ on the surfaces of the catalysts while Ru4+ would be in synergy with Co2+ concentration, and this also changed the chemical coordination of oxygen on the surface. Dispersion of Ru oxides on the cobalt oxides surface could not only improve the catalytic activity and stability on steam, but also decrease the amount of chlorinated by-products and increase HCl selectivity.
- Wang, Chao,Zhang, Chuanhui,Hua, Wenchao,Guo, Yanglong,Lu, Guanzhong,Gil, Sonia,Giroir-Fendler, Anne
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p. 99577 - 99585
(2016/11/02)
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- An acetylene and methylene chloride coupling reaction for preparing vinyl chloride production dichloroethylene and 1, 1, 2-trichloroethane method of
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The invention relates to a method for preparing vinyl chloride and coproducing dichloroethylene and 1,1,2-trichloroethane by acetylene-dichloromethane coupled reaction, which is characterized by comprising the following steps: mixing acetylene and dichloromethane, and simultaneously carrying out dichloromethane coupled reaction and acetylene hydrochlorination on the acetylene and dichloromethane in a catalyst-filled reactor under the action of the catalyst, wherein the mole ratio of the acetylene to the dichloromethane is 0.5-2.5, the reaction temperature is 200-400 DEG C, the volumetric space velocity of the acetylene-dichloromethane gas mixture is 10-500 h, and the dichloromethane coupled reaction generates dichloroethylene, 1,1,2-trichloroethane and chlorine hydride; and further carrying out acetylene hydrochlorination on the generated chlorine hydride and acetylene to generate vinyl chloride. The method can simultaneously coproduce the dichloroethylene, 1,1,2-trichloroethane and other high-added-value products while producing vinyl chloride, and the process is more economical and has wider industrialization prospects.
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Paragraph 0038; 0039; 0045; 0046
(2017/02/09)
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- REACTOR AND METHOD FOR REACTING AT LEAST TWO GASES IN THE PRESENCE OF A LIQUID PHASE
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A reactor for reacting at least two gases in the presence of a liquid phase, provided with an external liquid phase circulation device and including at least one injector for injecting the gases and the externally circulated liquid phase. In the injector the mixing of the gases together and with the externally circulated liquid phase only begins at the outlet of the injector.
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Page/Page column 3
(2009/07/25)
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- PROCESS FOR THE PRODUCTION OF VINYL CHLORIDE
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The present invention relates to a process for the production of vinyl chloride by thermal cracking of 1,2-dichloroethane (EDC) to form a reaction mixture containing vinyl chloride (VCM), hydrogen chloride (HCI), unconverted 1,2-dichloroethane, the impurity 1,3-butadiene and other by-products in which the troublesome by-product 1,3-butadiene is removed. The reaction mixture is quenched and said vinyl chloride is separated from said mixture. Said 1,3-butadiene is removed from said quenched mixture prior to said vinyl chloride separation by reacting with chlorine added to said mixture after addition of a butadiene reduction agent to said mixture. The butadiene reduction agent is selected from the classes of compounds known to or expected to act as radical scavengers. The butadiene reduction agent is an aromatic compound selected from the groups consisting of aromatics with one or more oxygen attached to the ring. Preferably, said butadiene reduction agent is a para-substituted phenol as 4-methoxyphenol, 4-cresol or hydroquinone.
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(2008/06/13)
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- Reactions of chlorinated vinylsilanes with hydrogen chloride
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Catalytic hydrochlorination of a series of chloro(chlorovinyl)methylsilanes was studied. The course of the reaction depends on the number and position of the chlorine atoms in the initial monomers.
- Lakhtin, V. G.,Ryabkov, V. L.,Kisin, A. V.,Nosova, V. M.,Chernyshev, E. A.
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p. 375 - 378
(2007/10/03)
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- Competing electron transfer, proton abstraction and nucleopilic substitutions in gas-phase reactions of (radical) anions with chloro- and bromomethanes
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The product ion distributions and rates of the gas-phase reactions of two series of (radical) anions with chloroand bromomethanes (CH3Cl, CH2Cl4, CH3Cl3, CCl4, CH3Br, CH2Br2, CHBr3 and CBr4) were determined with the use of Fourier transform ion cyclotron resonance (FT-ICR) mass spectromelry. The first series consists of anions (HO-, CH3O-, C2H5O-, C3H7O- and CH3S-), for which the corresponding neutral radicals have a relatively high electron affinity (EA > 150 kJ mol-1). The second series consists of (radical) anions (CH2S-, CH2-CHCH2-, CH2-C(CH3)CH2-, C6H4- and C6H5-), for which the corresponding neutral species have a relatively low electron affinity (EA -1). These (radical) anions react mainly with the halomethanes to afford (i) halide ions, (ii) halomethyl anions with the same number of halogen atoms as in the parent halomethane and (iii) halomethyl anions with one halogen atom less than the parent substrate. The last process involves nucleophilic attack on a halogen atom and is particularly important in the reactions with substrates containing three or four halogen atoms. The halide ions may arise by a number of different pathways, such as SN2 substitution, α-elimination, halogen attack followed by dissociation of the thus formed halomethyl anion and overall dissociative electron transfer. The SN2 process is held responsible for the formation of halide ions in the reactions with monohalomethanes, whereas α-elimination is likely to be of importance only for the reactions with trichloro- and tribromomethanes. Attack on a halogen atom followed by dissociation of the ion generated initially is likely to be important if CCl4 or CBr4 is the substrate. Electron transfer is only a dominant pathway in the reactions of the CH2S- ion with the halomethanes. The occurrence of electron transfer in the reactions of this ion with CHCl3, CCl4 and CHBr3 is evidenced by the formation of minor amounts of stable halomethane radical anions in addition to the generation of CH2SCl- or CH2SBr- ions and abundant halide ions. The interplay between the various possible reactions is discussed on the basis of thermodynamic considerations and the rates of the overall processes.
- Staneke,Groothuis,Ingemann,Nibbering
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p. 471 - 486
(2007/10/03)
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- MECHANISMS OF FREE-RADICAL REACTIONS XXX. MECHANISM OF FREE-RADICAL CHLORINATION OF ORGANIC COMPOUNDS BY SODIUM HYPOCHLORITE IN THE PRESENCE OF PHASE-TRANSFER CATALYSTS
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The reaction of hydrocarbons and their derivatives with sodium hypochlorite in the presence of phase-transfer catalysts and also with dichlorine monoxide takes place by a common free-radical mechanism, and the hydrogen atom is abstracted both by the chloroxy radical and by the chlorine radical.In the range of pH 7-9 it is possible to conduct the free-radical chlorination process with a minimal contribution from the site processes involving oxidation and ionic chlorination of the alkyl aromatic substrates.The relative rate constants for a series of organic substrates was measured by the method of competing reactions.The observed selectivity of the process is a quantity that depends on the relative contribution from the two competing mechanisms.
- Dneprovskii, A. S.,Eliseenkov, E. V.
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p. 235 - 240
(2007/10/02)
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- THE EFFECT OF NONCOMPLEXING SOLVENTS ON THE SELECTIVITY OF THE FREE-RADICAL CHLORINATION OF 1,1-DICHLOROETHANE
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During study of the effect of noncomplexing solvents (dichloromethane, pentachloroethane, hexachloroacetone, nitromethane) on the selectivity of the photochlorination of 1,1-dichloroethane correlations for each of them were obtained between the rate constants for the abstraction of a hydrogen atom by the chlorine radical and the various positions of the substrate.These relations were compared with the analogous relations for Freon 113 and acetic acid.A satisfactory correlation was obtained between these relations and the solvent parameters.The obtained results were interpreted in terms of theories on the solvated character of the chlorine radicals.The departure of the point corresponding to acetic acid from the correlation was explained by specific interactions between 1,1-dichloroethane and the solvent.
- Aver'yanov, V. A.,Vlasov, D. V.
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p. 1521 - 1525
(2007/10/03)
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- Process for the preparation of penem compounds
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Compound I STR1 is obtained by reaction of compound II with compound III
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- REACTION OF ORGANIC COMPOUNDS WITH SF4-HF-HALOGENATING SYSTEM VII. REACTIONS OF OLEFINS WITH THE SF4-HF-Cl2(Br2) SYSTEM
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Under the influence of the SF4-HF-Cl2(Br2) system halogen-containing olefins undergo conjugate halogenofluorination.It was shown for the case of (Z)- and (E)- 1,2-dichloroethenes that these reactions take place anti-stereospecifically through the formation of the bromonium ions.The accumulation of chlorine atoms in the olefin molecule hinders electrophilic addition of stoichiometric equivalents of ClF and BrF at the double bond.The SF4-HF-Br2 system is an effective agent for substitutive fluorination of organic compounds containing bromine.Only the bromine atoms situated at the secondary carbon atom are substituted by fluorine.
- Kunshenko, B. V.,Mokhamed, Nagib Mukhtar,Omarov, V. O.,Muratov, N. N.,Yagupol'skii, L. M.
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p. 511 - 518
(2007/10/02)
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- A Novel Laser-induced Synthesis of 1,1-Dichloroethylene from 1,1-Dichloroethane
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The laser-induced photochlorination of 1,1-dichloroethane followed by its dehydrochlorination has been examined in a flow reactor under normal pressure at 25 - 200 deg C, which has been proved to be a novel direct synthesis of vinylidene chloride.
- Oshima, Yoshito,Iguchi, Kayoko,Tominaga, Hiro-o,Koda, Seiichiro
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p. 2101 - 2104
(2007/10/02)
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- Process for producing tetrabromobisphenol A
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A process for producing tetrabromobisphenol A, which comprises brominating bisphenol A in methanol, wherein the substrate concentration of bisphenol A to methanol is at most 20 wt/vol %.
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- KrF Laser-induced Thermal Decomposition of 1,2-Dichloroethane
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The thermal decomposition of 1,2-dichloroethane to give vinyl chloride and hydrogen chloride has been reinvestigated at 703 K and the major features of this free-radical chain reaction found previously have been confirmed.A direct comparison of the pulsed KrF laser-induced process (248 nm) in the same static reactor at this temperature showed that a substantial increase in rate occurs even at low pulse-repetition rates (2 Hz).In an extended study of the laser-induced reaction at temperature where thermal reaction is negligible (476-577 K), quantum yields of vinyl chloride formation have been measured to be between 3000 and 13 000.Quantum yields decreased slighthly with increasing pressure and showed an inverse square-root dependence on initial chlorine atom concentration.The major by-products were identified as ethene, ethyne, 1,2,3,4-tetrachlorobutane and 1,1,2-trichloroethane.At 577 K and 150 Torr, the quantum yield of ethene production is close to unity, indicating that under these conditions reaction (2) is essentially complete. C2H4Cl2 + hν (248 nm) --> CH2ClCH2* + Cl (1) CH2ClCH2* --> C2H4 + Cl (2) Computer modelling of a complete reaction mechanism involving the propagation steps (3) and (4) Cl + C2H4Cl2 --> C2H3Cl2 + HCl (3) C2H3Cl2 --> C2H3Cl + Cl (4) was used to predict quantum yields of both vinyl chloride and the minor products.
- Dyer, Peter E.,Matthews, Martin,Holbrock, Kenneth A.,Oldershaw, Geoffrey A.
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p. 2151 - 2156
(2007/10/02)
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- EFFECT OF AROMATIC SOLVENTS ON THE RATE OF FREE-RADICAL CHLORINATION. CHLORINATION OF 1,2-DICHLOROETHANE IN THE PRESENCE OF o-DICHLOROBENZENE
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The rate of the azobisizobutyronitrile-initiated chlorination of 1,2-dichloroethane in the presence of o-dichlorobenzene obeys a complex equation of fractional orders in 1,2-dichloroethane, o-dichlorobenzene, and the initiator.The obtained data are interpreted in terms of a mechanism involving chlorine atoms or their ? complexes with the aromatic molecules ArH Cl as chain transfer agents.On the basis of the parameters of the kinetic equation and known data on the rate constants of chain initiation and termination reactions an estimate is given of the rate constants for the abstraction of hydrogen from 1,2-dichloroethane by the C6H4Cl2 Cl complexes (0.67.105 liter/mole.sec) and the ratio of the rate constants for the formation of the C6H4Cl2 Cl complexes and the abstraction of hydrogen from 1,2-dichloroethane by the chlorine atoms (15.2).
- Aver'yanov, V. A.,Ruban, S. G.,Shvets, V. F.
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p. 782 - 788
(2007/10/02)
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- Reactivity and Intersystem Crossing of Singlet Methylene in Solution
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Evidence is reported wich demonstrates that singlet methylene, produced from the photolysis of diazomethane or diazirine undergoes intersystem crossing to form triplet methylene in perfluorohexane solvent.The results of triplet sensitized photolysis and of direct photolysis experiments with dilute concentrations of substrate (cis- and trans-2-pentene and chloroform) appear to be essentially identical.Stern-Volmer analyses of the competition kinetics between acetonitrile and 2-pentenes or chloroform for singlet methylene are consistent with the near diffusion controlled reactivity of singlet methylene.With the assumption of diffusion-controlled reactions for singlet methylene, plots of the quantum yield for singlet vs. triplet reaction for methylene allow the first estimate (-1) of the rate of intersystem crossing of singlet methylene in the condensed phase.This value is considerably smaller than the value that is extrapolated to the solution phase from results in the gas phase.The possible reasons for this difference are discussed.
- Turro, Nicholas J.,Cha, Yuan,Gould, Ian R.
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p. 2101 - 2107
(2007/10/02)
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- EFFECT OF SPECIFIC SOLVATION ON THE SELECTIVITY OF THE FREERADICAL CHLORINATION OF CHLOROETHANES
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The chlorination of 1,1-dichloroethane in the presence of the complex-forming solvent chlorobenzene was investigated.It was shown that the dilution of 1,1-dichloroethane under the conditions of a constant chlorobenzene concentration leads to a decrease in the / ratio.The results contradict the previously published view concerning the possibility of self-association in chloroethanes through the formation of hydrogen bonds and the effect of such association on the selectivity of the liquid-phase chlorination of chloroethanes.
- Aver'yanov, V. A.,Ruban, S. G.
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p. 1465 - 1466
(2007/10/02)
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- EFFECT OF ACETIC ACID ON THE SELECTIVITY OF FREE-RADICAL CHLORINATION PROCESSES
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The effect of acetic acid on the selectivity of the chlorination of 1,1-dichloroethane and 2-chloropropane in the range of temperatures between -10 and 60 deg C was investigated.It was shown that increase in the acetic concentration leads to a decrease in the amount of products from chlorination at the chlorine-substituted position, and in the region of high solvent concentrations the selectivity of chlorination becomes insensitive to temperature.The results are discussed from the standpoint of the increase in the steric and energy hindrances during attack at the more substituted positions due to the solvatation of the chlorine atoms and the substrate molecules.
- Aver'yanov, V. A.,Ruban, S. G.
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p. 2267 - 2269
(2007/10/02)
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- The Decomposition of Azobisisobutyronitrile under the Conditions of Free-radical Chlorinaton
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The kinetics of the decomposition of azobisiobutyronitrile in the 1,2-dichloroethane-carbon tetrachloride-chlorine system have been investigated and it is shown that, in free-radical chlorination, there is competition between the chain and unimolecular mechanisms of the decomposition of azobisiobutyronitrile.
- Ruban, S. G.,Aver'yanov, V. A.,Moiseeva, L. V.
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p. 148 - 150
(2007/10/02)
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- Reactions of N-Pentafluorosulfanylurethanes and Thiolurethanes with Phosphorus Pentachloride
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Urethanes of the type SF5NHC(O)OR react with PCl5 to give primarily SF5NCO.In only one case, where R = C6H5, was any evidence for an imine product observed.The corresponding reactions of SF5NHC(O)SR compounds give both SF5NCO and the imine product.The new compounds SF5N=C(Cl)SCH3 and SF5N=C(Cl)SC6H5 were identified by IR, NMR, and mass spectrometry.
- Thrasher, Joseph S.,Clifford, Alan F.
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p. 593 - 596
(2007/10/02)
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- Kinetics of Cl(2PJ) Reactions with the Chloroethanes CH3CH2Cl, CH3CHCl2, CH2ClCH2Cl and CH2ClCHCl2
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The kinetics of the reactions Cl(2PJ) + RHCl -> RCl + HCl were investigated over the temperature range 257-426 K for RHCl = CH3CH2Cl (k2), CH3CHCl2 (k3), CH2ClCH2Cl (k4), and CH2ClCHCl2 (k5).Cl(2PJ) was produced by 355 nm pulsed laser photolysis of Cl2 and monitored by time-resolved resonance fluorescence spectroscopy.The data are adequately described by the following Arrhenius expressions (units are cm3 molecule-1 s-1, errors are 2? and refer to precision only): k2=(2.34+/-0.42)E-11exp, k3=(8.19+/-1.84)E-12exp,k4=(2.21+/-0.51)E-11exp, and k5=(4.88+/-1.41)E-12exp.Under some experimental conditions evidence for Cl(2PJ) regeneration via a secondary reaction was observed.At 258+/-1 K, deviations of Cl(2PJ) temporal profiles from first-order behavior were attributable to the reactions RCl + Cl2 -> RCl2 + Cl(2PJ)(kj).By modeling the observed C(2PJ) temporal profiles, we found the rate constant kj to lie in the range (5-12)E-14 cm3 molecule-1 s-1 for all RCl investigated.The reactivity trends observed in reactions of Cl2PJ) with C2HXCl(6-x), x=3-6, are discussed.
- Wine, P. H.,Semmes, D. H.
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p. 3572 - 3578
(2007/10/02)
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- Chlorine-catalysed Pyrolysis of 1,2-Dichloroethane. Part 1.- Experimental Results and Proposed Mechanism
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Experimental studies of the pyrolysis and chlorination of 1,2-C2H4Cl2 in the presence of small proportions of chlorine, or of chlorine plus nitric oxide, confirm that the main propagating steps between 520 and 620 K are .The initial rates (d/dt)0 and (d/dt)0-decrease together as the vessels age, but k2/k3=γ remains constant at constant pDCE. γ increases as pDCE is increased, or if inert gases are added, as expected from unimolecular behaviour of k2, and the Arrhenius parameters of γ increase together as pDCE is increased. γ(p) is evaluated for several ranges of pDCE at five temperatures to allow study of k2(p) by unimolecular theory in Part 2.The addition of VC lowers (d/dt)0 through reaction (-2), and the results are used to evaluate k-2/k1; k-2 is also pressure-dependent.In vessels with fresh surfaces, d(VC)/dt is proportional to pDCExp0.5Cl for low pCl and is independent of added inert gases; in aged vessels, the order in pDCE becomes 0.62, very close to the dependence of γ(p) on pDCE.Calculations of .>0 and .>0 from the observed rates and rate constants point to an initiation step and termination by the reverse reaction in fresh-surfaced vessels, where S is a surface site; with aged surfaces, the results point to the same initiation step combined with termination by especially at lower temperatures.
- Ashmore, Philip G.,Gardner, John W.,Owen, Anthony J.,Smith, Barbara,Sutton, Philip R.
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p. 657 - 676
(2007/10/02)
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- MECHANISM OF THE SELECTIVE ACTION OF AROMATIC SOLVENTS ON FREE-RADICAL CHLORINATION. CHLORINATION OF 1,1-DICHLOROETHANE
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The effect of six solvent of aromatic nature (benzene, chlorobenzene, o-dichlorobenzene, fluorobenzene, tert-butylbenzene, nitrobenzene) on the selectivity of the free-radical chlorination of 1,1-dichloroethane was investigated.It was shown that the yield of 1,1,1-trichloroethane increases with increase in the concentration of the solvent and with decrease in the temperature.A mechanism based on the concept of the formation of ? complexes between the chlorine atom and the aromatic molecules is proposed for the selective action of the aromatic solvents on free-radical chlorination.Mathematical model agreeing with the pro posed mechanism for the selective action of the solvents were obtained for the selectivity in aromatic solvents.It was shown that the parameters of the selectivity models characterizing the capacity of the solvents for complex formation and the relative reactivity of the C-H bons to attack by the ? complexes vary in line with the electron-donating characteristics of the solvents.
- Aver'yanov, V. A.,Zarytovskii, M. V.,Shvets, V. F.,Treger, Yu. A.,Emel'yanov, V. I.
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- A Reexamination of the Photodissociation of CH2ClCH2Cl at 147 nm. Test for Chlorine Atom Reactions
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1,2-Dichloroethane has been photolyzed at 147 nm and ca. 23 deg C as a function of reactant pressure, the additives NO and CF4, and the conversion (It/N) which is a significant variable of the system.Also investigated was the 147-nm photolysis of a mixture of 1,2-C2H4Cl2 and C2H6 which provided unequivocal evidence for the presence of chlorine atoms in the system.The major primary process is the molecular production of ethylene (ψC2H4=0.67) by two Cl-atom elimination.Other observed reaction products are C2H3Cl and smaller quantities of C2H2 and CH2ClCHCl2.Approximately half of the vinyl chloride yield ψNOC2H3Cl=0.16) derives from the primary molecular elimination of HCl, while the balance can be attributed to radical reactions.The reaction kinetics are interpreted in terms of competitive processes of chlorine atoms which include H abstraction from the parent, Cl addition to the product olefins, and NO-catalyzed chlorine atom recombination, with H abstraction being the dominant secondary process.The results are discussed in relation to a recent investigation of this system, and contrasted to the 147-nm photolyses of more highly substituted chlorofluoroethanes for which the "two Cl-atom" mechanism has been demonstrated previously.The extinction coefficient for 1,2-C2H4Cl2 at 147 nm (296 K) has been determined as ε=(1/PL) ln(I0/It)=525 +/- 90 atm-1 cm-1.
- Yano, T.,Tschuikow-Roux, E.
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p. 3372 - 3377
(2007/10/02)
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