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1.
The reaction of 1,3-cyclopentadiene (CPD) with ground-state atomic oxygen O(3P), produced by mercury photosensitized decomposition of nitrous oxide, was studied. The identified products were carbon monoxide and the following C4H6 isomers: 3-methylcyclopropene, 1,3-butadiene, 1,2-butadiene, and 1-butyne. The yield of carbon monoxide over oxygen atoms produced (?CO) was equal to the sum of the yields of C4H6 isomers in any experiment. ?CO was 0.43 at the total pressure of 6.5 torr and 0.20 at 500 torr. We did not succeed in detecting any addition products such as C5H6O isomers. It was found that 3-methylcyclopropene was produced with excess energy and was partly isomerized to other C4H6 isomers, especially to 1-butyne. The excess energy was estimated to be about 50 kcal/mol. The rate coefficient of the reaction was obtained relative to those for the reactions of atomic oxygen with trans-2-butene and 1-butene. The ratios kCPD+O/ktrans-2-butene+O= 2.34 and kCPD+O/k1-butene+O = 11.3 were obtained. Probable reaction mechanisms and intermediates are suggested. 相似文献
2.
R. Atkinson J. Arey S. M. Aschmann E. C. Tuazon 《Research on Chemical Intermediates》1994,20(3-5):385-394
The formation yields of 1,2-epoxy-2-methyl-3-butene and 1,2-epoxy-3-methyl-3-butene have been measured from the reaction of O3 with isoprene at room temperature and one atmosphere total pressure of N2 and air diluents, with and without cyclohexane to scavenge the OH radicals formed in this reaction system. In addition, a relative rate method was used to determine a rate constant for the gas-phase reaction of O3 with 1,2-epoxy-2-methyl-3-butene of (2.5 ± 0.7) x 10-18 cm3 molecules-1 s-1 at 296 ± 2 K. Our data show that the epoxide yields in N2 and air diluents are the same, with formation yields of 1,2-epoxy-2-methyl-3-butene of 0.028 ± 0.007 and of 1,2-epoxy-3-methyl-3-butene of 0.011 ± 0.004. These data further show that the epoxides arise from the primary O3 reaction with isoprene, and not via the formation of O(3P) atoms from the O3 - isoprene reaction followed by reaction of these O(3P) atoms with isoprene. 相似文献
3.
Negative chemical ionization mass spectrometry is used as a probe to examine reactions between hydrocarbon radicals and metal complexes in the gas phase. The methane negative chemical ionization mass spectra of 27 complexes of cobalt(II ), nickel(II ) and copper(II ) in the presence of O4, O2N2 and N4 donor atom sets are characterized by two dominant series of adduct ions of the form [M + CnH2n]? and [M + CnH2n+1]? at m/z values above the molecular ion, [M]?. Insertion of the CH radical into the ligand followed by radical/radical recombination and electron capture is proposed as the major mechanism leading to the formation of [M + CnH2n]? adduct ions. A second pathway involves ligand substitution by CnH2n+1 radicals concomitant with H elimination and electron capture. Oxidative addition at the metal followed by ionization is suggested as the principal pathway for the formation of [M + CnH2n+1]? adduct ions. 相似文献
4.
The reaction of tetrachloroethylene, C2Cl4, with O(3P) atoms as well as the plasma decomposition of C2Cl4 and C2Cl4/O2 mixtures have been investigated by combined application of electron paramagnetic resonance (EPR) and emission and mass spectroscopies. C2Cl4 plasma decomposition is shown to proceed primarily to the formation of CCl3 radicals and chlorine-deficient products, which are ultimately involved in the formation of carbonaceous layers. A simple reaction model accounts for all the detected stable and radical species, encountered during the plasma decomposition. The model also enables order-of-magnitude estimates of decomposition rate constants to be made. The suppression of the formation of both carbonaceous layers and products CmCln (m3) in C2Cl4/O2 discharges is explained using results of an investigation of elementary reactions in the system C2Cl4/O(3P)/O2. The stable products of C2Cl4/O2 discharges, i.e., COCl2, CCl4, and C2Cl6, respectively, are shown to originate from recombination of the peroxy radicals CCl3OO and C2Cl5OO. 相似文献
5.
Loison JC Daranlot J Bergeat A Caralp F Mereau R Hickson KM 《The journal of physical chemistry. A》2010,114(51):13326-13336
Products of the reaction of OH radicals with propene, trans-2-butene, and 1-butene have been investigated in a fast flow reactor, coupled with time-of-flight mass spectrometry, at pressures between 0.8 and 3.0 Torr. The product determination includes H atom abstraction channels as well as site-specific OH addition. The OH radicals are produced by the H + NO(2) → OH + NO reaction or by the F + H(2)O → OH + HF reaction, the H or F atoms being produced in a microwave discharge. The gas mixture is ionized using single photon ionization (SPI at 10.54 eV), and products are detected using time-of-flight mass spectrometry (TOF-MS). The H atom abstraction channels are measured to be <2% for OH + propene, 8 ± 3% for OH + 1-butene, and 3 ± 1% for OH + trans-2-butene. Analysis of ion fragmentation patterns leads to 72 ± 16% OH addition to the propene terminal C atom and 71 ± 16% OH addition to the 1-butene terminal C atom. The errors bars represent 95% confidence intervals and include estimated uncertainties in photoionization cross sections. 相似文献
6.
The kinetics of the gas-phase reactions of O3 with a series of alkenes have been investigated at atmospheric pressure (ca. 740 torr) of air and 296 ± 2 K, using a relative rate method in the presence of sufficient n-octane to scavenge any OH radicals generated in these reactions. Relative to k(O3 + propene) = 1.00, the rate constants obtained were: 1-butene, 0.975 ± 0.030; 2-methylpropene, 1.14 ± 0.04; 2-methyl-1,3-butadiene (isoprene), 1.21 ± 0.02; 1,4-cyclohexadiene, 4.75 ± 0.23; cyclohexene, 7.38 ± 0.48; cis-2-butene, 12.8 ± 0.8; trans-2-butene, 21.5 ± 1.5; 2-methyl-2-butene, 42.1 ± 2.8; cyclopentene, 64.9 ± 4.3; and 2,3-dimethyl-2-butene, 123 ± 11. These relative rate constants have been placed on an absolute basis using a rate constant for the reaction of O3 with propene of 1.01 × 10?17 cm3 molecule?1 s?1 at 296 K derived from an analysis of the available literature data. The resulting rate constants then lead to a self-consistent set of room temperature data for the reactions of O3 with these alkenes. © John Wiley & Sons, Inc. 相似文献
7.
L. I. Kuznetsova N. I. Kuznetsova R. I. Maksimovskaya O. S. Koshcheeva V. A. Utkin 《Kinetics and Catalysis》2013,54(4):420-430
The homogeneous oxidation of 1,3-butadiene (BD) in H2O2-HPC-CH3CN (HPC = heteropoly compound) solutions has been investigated. The route of the reaction depends on the nature of the metal capable of coordinating with active oxygen in the HPC. The products of radical BD oxidation (acrolein, 3-butene-1,2-diol, 2-butene-1,4-diol, furan) form in the presence of H3+n PMo12 ? n V n O40 (n = 1, 2) acids. 3,4-Epoxy-1-butene (EB) and acrolein + furan, which form in equal amounts in the presence of the (n-Bu4N)5PW11O39Fe(OH) salt, result, respectively, from the electrophilic addition of hydrogen peroxide to BD and from radical BD oxidation on iron-oxygen complexes in the HPC composition. The reaction carried out in the presence of (n-Bu4N)3{PO4[WO(O2)2]4}, (n-Bu4N)5Na0.6H1.4PW11O39, or (EMIm)5NaHPW11O39 yields EB with high selectivity on the reacted BD basis (up to 97%) and H2O2 (about 100%). The formation and conversion of the phosphotungstate peroxo complexes PW n O m α? (n = 2, 3, 4) that are active in BD epoxidation have been investigated by 31PNMR spectroscopy. The role of the tetrabutylammonium and ethylmethylimidazolium cations in the formation of these complexes has been demonstrated. 相似文献
8.
Employing low temperature thermal measurements, heat capacities (Cs) in the crystal and liquid states, and phase transition data, Tm and ΔHm, the condensed phase thermodynamic properties, (Gs -H°0)/T, Hs -H°0, Ss and Cs, in the temperature range 0–360 K were evaluated for the following eleven alkenes: ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, 1-pentene, cis-2-pentene, trans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene and 2-methyl-2-butene. The sources of experimental data, methods of evaluation, and the calculated results are described in detail. 相似文献
9.
To test some predictions of the spur model of positronium (Ps) formation, positron lifetime studies were made of the following binary organic mixtures: (a) carbondisulphide mixtures with n-tetradecane, n-hexane, isooctane, neopentane, and tetramethylsilane (TMS); (b) neopentane mixtures with methanol, ethanol, cyclohexanol, and methylcyclohexane; (c) cis-2-butene/trans-2-butene, and benzene/ethanol. The results were in agreement with the model. A minimum in the Ps yield versus CS2 concentration, explained as being caused by electron localization on CS2 at low and delocalization on several CS2 molecules at higher CS2 concentration, depended on the electron work function Vo of the solvent. This minimum was pronounced (shallow or absent) at high (low) Vo. Solvation of electrons and positrons in alcohol clusters strongly influenced the Ps yield for the neopentane mixtures. The Ps yield was higher in cis- than in trans-2-butene. The Ps formation process in polar liquids is discussed. Experiment facts do not preclude that Ps is also formed by the encounter pair process of fully solvated particles in the positron spur. 相似文献
10.
Negative chemical ionisation mass spectrometry is used as a probe to identify reactions between hydrocarbon radicals and cornplexed cobalt(II) centres in the gas phase. Methane NCI mass spectra of a series of cobalt(II) complexes containing O4, O2N2 and N4 donor atom sets are characterised by adduct ions of the form [M + CnH2n+1]? at m/z values above the molecular ion, [M]?. Formation of such ionic species has been rationalised in terms of a one-electron oxidative-addition mechanism involving attack by hydrocarbon plasma-derived alkyl radicals at the metal centre prior to electron capture: CoIILn + R? → RCoIIILn [CoILn]?. The competing resonance electron attachment reaction: CoIILn also occurs within the ion source. 相似文献
11.
J Ortega J.S Matos M.I Paz Andrade E Jimenez 《The Journal of chemical thermodynamics》1985,17(12):1127-1132
Excess molar volumes VmE were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The VmE values were all positive, decreasing with the n value of the ester: Cn?1H2n?1CO2C2H5. 相似文献
12.
Nine novel sulfate-type hybrid surfactants, CmF2m+1C6H4CH(OSO3Na)CnH2n+1 (FmPHnOS: m=4, 6, 8; n=3, 5, 7; C6H4: p-phenylene), with a benzene ring in their molecules were synthesized. Alkanoyl chlorides were allowed to react with iodobenzene in the presence of aluminum chloride to give the corresponding aromatic ketones. The reaction of the ketones with perfluoroalkyl iodides yielded 1-[4-(perfluoroalkyl)phenyl]-1-alkanones as intermediates. The intermediates were allowed to react with methanol in tetrahydrofuran in the presence of sodium borohydride to yield 1-[4-(perfluoroalkyl)phenyl]-1-alkanols. The desired hybrid surfactants were obtained by the reaction of 1-[4-(perfluoroalkyl)phenyl-1-alkanols with sulfur trioxide/pyridine complex in pyridine and by the subsequent neutralization of the products with sodium hydroxide solution. When compared with the conventional hybrid surfactants, CmF2m+1C6H4COCH(SO3Na)CnH2n+1 (FmHnS: m=4, 6; n=2, 4, 6; C6H4: p-phenylene), the new hybrid surfactants thus synthesized were found to have a comparable ability to lower the surface tension of water and a high hydrophilicity. The cmc of FmPHnOS obeyed Kleven’s rule and their occupied areas per molecule increased with increasing m and n with the values between 0.66 and 1.05 nm2. The aggregation number for FmPHnOS micelles ranged from 6 to 45 and the hydrodynamic radius of the micelles was in the range of 1.4-3.1 nm. 相似文献
13.
Farhan Arafin Andrew Laich Erik Ninnemann Robert Greene Ramees K. Rahman Subith S. Vasu 《国际化学动力学杂志》2020,52(11):739-751
Shock tube experiments have been carried out on 2-methyl-1-butene (2M1B), 2-methyl-2-butene (2M2B), and 3-methyl-1-butene (3M1B)—the three isomers of methyl butene compound. Carbon monoxide (CO) time-histories and ignition delay times are obtained behind reflected shockwaves over the temperature range of 1350-1630 K and pressures of 8.3-10.5 atm with stoichiometric mixtures of 0.075% fuel in O2/Ar. Comparative ignition study reveals that 3M1B ignites significantly faster than the other two isomers, while 2M1B dissociates earlier but ignites later than 2M2B. Possible mechanisms for this behavior are discussed with ignition delay time sensitivity and reaction path analysis. In addition, time-resolved CO measurements are compared with three different reaction mechanisms from the literature. Sensitivity analyses have been carried out to identify important reactions that need attention to accurately predict the chemistry of these isomers. Further investigation into the rates of unimolecular fuel decomposition reactions and C3H3 + O2 = CH2CO + HCO reaction are suggested based on the current investigation. 相似文献
14.
Recent progress on the bismuth molybdate catalysts for oxidative dehydrogenation of n-butene to 1,3-butadiene was reported in this review. A number of bismuth molybdate catalysts, including pure bismuth molybdates
(α-Bi2Mo3O12, β-Bi2Mo2O9, and γ-Bi2MoO6) and multicomponent bismuth molybdates, were prepared by a co-precipitation method for use in the production of 1,3-butadiene
from C4 raffinate-3 through oxidative dehydrogenation of n-butene. It was observed that multicomponent bismuth molybdate catalyst was more efficient than pure bismuth molybdate catalyst
in the oxidative dehydrogenation of n-butene. Various experimental measurements such as temperature-programmed reoxidation, X-ray photoelectron spectroscopy, and
O2-temperature-programmed desorption analyses were carried out to elucidate the different catalytic activity of bismuth molybdate
catalysts. It was revealed that a bismuth molybdate catalyst with a higher oxygen mobility showed a better catalytic performance
in terms of conversion of n-butene and yield for 1,3-butadiene. We have successfully demonstrated from experimental findings that oxygen mobility of
bismuth molybdate catalyst played a key role in determining the catalytic performance in the oxidative dehydrogenation of
n-butene to 1,3-butadiene. 相似文献
15.
The rate constants for the reactions C2O + H → products (1) and C2O + H2 → products (2) have been determined at room temperature by means of laser-induced fluorescence detection of C2O radicals, generated either by the KrF excimer laser photolysis Of C3O2, or by the reaction of C3O2 with O atoms. Values of k1 = (3.7 ± 1.0) × 10?11 cm3 s?1 and k2 = (7 ± 3) × 10?13 cm3 s?1 were obtained. 相似文献
16.
Direct on-line studies of a C2HCl3/He/O2 microwave discharge plasma made possible the evolution and detection of many unfamiliar ionic species. Numerous ionic chlorocarbons,
chlorohydrocarbons, oxygenated chlorohydrocarbons, oxygenated hydrocarbon radicals, and simple hydrocarbon species were identified
mass spectrometrically as by-products: C
m
Cl
n
(m = 1–4, 6, 8; n = 1–8), C
m
H
n
Cl
x
(m = 1–4, 6, 7, 10; n, x = 1–6), C
m
H
n
Cl
x
O
y
(m = 1–5, 12; n = 1–7; x = 1, 2, 4, 6; y = 1–3),
C
n
H2n−1O (n = 2, 3), C
m
H
n
(m = 2, 4, 6, 8; n = 2, 4), and so on. The studies clearly showed the presence of various unfamiliar positive ionic O-containing species such
as C2ClO2, CCl3CO, C2H2Cl4O2, and C4H2Cl6O3. It is apparent that positive-ion reactions play a significant role in producing many ionic species in the chemistry of C2HCl3 plasmas. 相似文献
17.
The reaction C2H5 + O2 → C2H5O2 in glassy methanol-d4 and the H-atom abstraction by CH3, C2H5, and n-C4H9 radicals in C2H5OH + C2D5OH and CD3CH2OH + C2D5OH glassy mixtures have been studied by electron spin resonance. The analysis of the dependence of the reaction rates on the concentration of O2 (oxidation) and C2H5OH, CD3CH2OH (H-atom abstraction) has shown that the √t law is not conditioned by the existence of regions characterized by different rate constants. 相似文献
18.
C2O radicals have been detected in the C3O2 + O flame system by laser-induced fluorescence. The dependence of [C2O] on [O] has been measured and its implications for the elementary reactions occuring in the C3O2 + O and hydrocarbonatom flame systems are discussed. 相似文献
19.
烯烃歧化反应(又称烯烃复分解反应)是两分子烯烃通过碳-碳键断裂重排生成新烯烃分子的反应,自1964年Phillips公司的Banks等发现以来,引起了研究者的广泛关注,且在均相催化体系的发展尤为迅速;与此同时,多相烯烃歧化催化剂因其在分离简单、可循环再生利用方面的优势而在工业界崭露锋芒.多相烯烃歧化催化剂通常由活性金属组分(Re,Mo,W)分散到大比表面积的多孔载体制备而成.多相催化剂上烯烃歧化反应主要集中在乙烯和2-丁烯反歧化制丙烯反应,其中WO_3/SiO_2催化剂先后应用于Phillips公司的Triolefin Process和ABB Lummus公司的OCT工艺,低温Re系催化剂被法国石油研究院应用到Meta-4歧化工艺.同时丙烯歧化也是研究最多的反应,多数情况下被用作探针反应来研究催化剂的性能.烯烃歧化反应可以根据市场需求灵活调变产物分布,为碳四烃类的高效转化利用提供很好的途径.受国内拉动内需的政策及下游应用行业强劲需求的影响,中国液化石油气的产量逐年递增.2014年我国液化气产量约为2550万吨,其中仅有39%左右用于碳四深加工,大部分当做燃料直接烧掉.从组成来看,液化气中烯烃含量在40%-50%,可以转化为高附加值的乙烯和丙烯进一步利用.本文重点开发了一条从1-丁烯出发生产乙烯/己烯的反应路线及对应的催化剂.首先从热力学角度分析了碳四歧化反应网络中各反应路径发生的难易程度.在此基础上,以Mo/Al_2O_3为催化剂考察了Mo负载量和反应条件对产物分布的影响-.在优化的6Mo/Al_2O_3催化剂上,80°C,1.0 MPa和丁烯空速3 h1的条件下,产物中乙烯和己烯的摩尔选择性超过85%,并且在48 h内保持良好的反应稳定性.为了进一步探究催化剂结构与反应性能的关系,系统考察了催化剂载体差异对Mo物种状态和反应性能的影响.借助N2吸附,NH_3-TPD,Py-IR,H_2-TPR,UV-Vis和HRTEM等表征手段,发现催化剂反应活性与其酸密度直接相关.催化剂酸量越大,丁烯转化率越高,但副反应越多;载体适宜的酸量和较大的比表面积更有利于钼物种的分散和四配位钼物种的形成,促进目标1-丁烯自歧化制乙烯/己烯反应的发生. 相似文献
20.
Dr. Xun‐Lei Ding Xiao‐Nan Wu Dr. Yan‐Xia Zhao Jia‐Bi Ma Prof. Sheng‐Gui He 《Chemphyschem》2011,12(11):2110-2117
Cerium oxide cluster cations (CemOn+, m=2–16; n=2m, 2m±1 and 2m±2) are prepared by laser ablation and reacted with acetylene (C2H2) in a fast‐flow reactor. A time‐of‐flight mass spectrometer is used to detect the cluster distribution before and after the reactions. Reactions of stoichiometric CemO2m+ (m=2–6) with C2H2 produce CemO2m?2+ clusters, which indicates a “double‐oxygen‐atom transfer” reaction CemO2m++C2H2→CemO2m?2++(CHO)2 (ethanedial). A single‐oxygen‐atom transfer reaction channel is also identified as CemO2m++C2H2→CemO2m?1++C2H2O (at least for m=2 and 3). Density functional theory calculations are performed to study reaction mechanisms of Ce2O4++C2H2, and the calculated results confirm that both the single‐ and double‐oxygen‐atom transfer channels are thermodynamically and kinetically favourable. 相似文献