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1.
The kinetics of polymerization of 1, 3-dioxolane (DiOX) initiated by (C2H5)3O+SbCl6 and SbCl5 has been studied and the elementary stages of the process have been considered. The polymerization of DiOX by (C2H5)3O+SbCl6-is shown to proceed at a steady rate to high conversion. A constant concentration of active centers in the system is maintained due to the equal rates of decomposition of active centers and disproportionation. The nonsteady-state character of DiOX polymerization initiated by SbCl5is associated with a relatively lower stability of the counter-ion SbCl5 OR? compared with SbCl6. The initiation of DiOX polymerization by (C2H5)3O+SbCl6 proceeds without hydride-transfer reactions, and the concentration of active centers in the system is determined not by processes taking place in the initiation stage, but by the existence of a definite kind of equilibrium with the participation of active centers. 相似文献
2.
Reactions of Fe+ and FeL+ [L=O, C4H6, c-C5H6, C5H5, C6H6, C5H4(=CH2)] with thiophene, furan, and pyrrole in the gas phase by using Fourier transform mass spectrometry are described. Fe+, Fe(C5H5)+, and FeC6H 6 + yield exclusive rapid adduct formation with thiophene, furan, and pyrrole. In addition, the iron-diene complexes [FeC4H 6 + and Fe(c-C5H6)+], as well as FeC5H4(=CH2)+ and FeO+, are quite reactive. The most intriguing reaction is the predominant direct extrusion of CO from furan by FeC4H6 +, Fe(c-C5H6)+, and FeC5H4(=CH2)+. In addition, FeC4H 6 + and Fe(c-C5H6)+ cause minor amounts of HCN extrusion from pyrrole. Mechanisms are presented for these CO and HCN extrusion reactions. The absence of CS elimination from thiophene may be due to the higher energy requirements than those for CO extrusion from furan or HCN extrusion from pyrrole. The dominant reaction channel for reaction of Fe(c-C5H6)+ with pyrrole and thiophene is hydrogen-atom displacement, which implies DO(Fa(N5H5)+-C4H4X)>DO(Fe(C5H5)+-H)=46±5 kcal mol?1. DO(Fe+-C4H4S) and DO(Fe+-C4H5N)=DO(Fe+-C4H6)=48±5 kcal mol?1. Finally, 55±5 kcal mol?1=DO(Fe+-C6H6)>DO(Fe+-C4H4O)>DO(Fe+-C2H4)=39.9±1.4 kcal mol?1. FeO+ reacts rapidly with thiophene, furan, and pyrrole to yield initial loss of CO followed by additional neutral losses. DO(Fe+-CS)>DO(Fe+-C4H4S)≈48±5 kcal mol?1 and DO(Fe+-C4H5N)≈48±5 kcal mol?1>DO(Fe+-HCN)>DO(Fe+-C2H4)=39.9±1.4 kcal mil?1. 相似文献
3.
Dr. Beni B. Dangi Dr. Dorian S. N. Parker Dr. Tao Yang Prof. Ralf I. Kaiser Prof. Alexander M. Mebel 《Angewandte Chemie (International ed. in English)》2014,53(18):4608-4613
Dicarbon (C2), the simplest bare carbon molecule, is ubiquitous in the interstellar medium and in combustion flames. A gas‐phase synthesis is presented of the benzyl radical (C6H5CH2) by the crossed molecular beam reaction of dicarbon, C2(X1Σg+, a3Πu), with 2‐methyl‐1,3‐butadiene (isoprene; C5H8; X1A′) accessing the triplet and singlet C7H8 potential energy surfaces (PESs) under single collision conditions. The experimental data combined with ab initio and statistical calculations reveal the underlying reaction mechanism and chemical dynamics. On the singlet and triplet surfaces, the reactions involve indirect scattering dynamics and are initiated by the barrierless addition of dicarbon to the carbon–carbon double bond of the 2‐methyl‐1,3‐butadiene molecule. These initial addition complexes rearrange via multiple isomerization steps, leading eventually to the formation of C7H7 radical species through atomic hydrogen elimination. The benzyl radical (C6H5CH2), the thermodynamically most stable C7H7 isomer, is determined as the major product. 相似文献
4.
Dmitri V. Zagorevskii John L. Holmes 《Journal of the American Society for Mass Spectrometry》1994,5(10):928-934
Ion-molecule reactions of chromium containing ions with arylsulfides have been studied in the gas phase and their products have been characterized by tandem mass spectrometry. C6H5SH and (C6H5)2S react as typical aromatic compounds and give rise to Cr+C6H5SR] and RC6H5Cr+QH5SR′ [R = H, CH3, CH(CH3)2; R′ = H, C6H5] ions. Metastable ion mass spectra of the latter species show that the metal is more strongly bound to diphenylsulfide than to alkylbenzenes. C6H5SSC6H5 reacts with chromium-containing ions to form only Cr+(C6H5SSC6H5). The decomposition characteristics of this ion and, in particular, the presence of a recovery signal in the neutralization-reionization mass spectrum are in keeping with the formation of a 1,2-dithia[2]cyclophane complex ion, which rearranges into a structurel(s) that contains Cr?S bond(s). No evidence was found for metal atom insertion into S?S, C?S, or S?H bonds. 相似文献
5.
Critical energies for 1,3-R sigmatropic migrations (R?H, OH, CH3 and C6H5) have been calculated by means of the MINDO/3 method. This investigation was carried out for the system [RCH2CH?CH2]+˙ and the results indicated that hydroxyl group migration is energetically favoured (critical energy = 53 kJ mol?1). Calculations are also presented for [3-buten-2-ol]+˙ isomerizations. The lowest energy pathway is related to the [2-buten-1-ol]+˙; the corresponding critical energy for OH migration is equal to 33 kJ mol?1 in this case. 相似文献
6.
G. Bouchoux Y. Hoppilliard P. Jaudon R. Houriet 《Journal of mass spectrometry : JMS》1984,19(8):394-397
The proton transfer equilibrium reactions involving 3-penten-2-one, 3-methyl-3-buten-2-one, crotonic acid and methacrylic acid were carried out in an ion cyclotron resonance (ICR) spectrometer. The semiempirical method MNDO, used to estimate the heats of formation for 14 protonated [C5H9O]+ and [C4H7O2]+ ions and the energetic aspect of the fragmentations of metastable [C6H12O]+. and [C6H12O2]+. ions, leads to the conclusion that the ions corresponding to protonation at the carbonyl oxygen are the most stable. Thus the experimentally determined heats of formation of protonated olefinic carbonyl compounds can be attributed to the following structures: [CH3COHCHCHCH3]+ (δHf = 490 KJ mol?1), [CH3COHC(CH3)CH2]+ (δHf = 502 KJ mol?1), [HOCOHCHCHCH3]+ (δHf = 330 KJ mol?1) and [HOCOHC(CH3)CH2]+ (δHf = 336 KJ mol?1). 相似文献
7.
Run‐Chang Liu Yong‐Qiang Ma Lin Yu Jin‐Shan Li Jing‐Rong Cui Rui‐Qing Wang 《应用有机金属化学》2003,17(9):662-668
A series of arylantimony ferrocenecarboxylates with the formula (C5H5FeC5H4CO2)nSbAr(5?n) (n = 1, 2; Ar = C6H5, 4‐CH3C6H4, 3‐CH3C6H4, 2‐CH3C6H4, 4‐ClC6H4, 4‐FC6H4) were synthesized and characterized by elemental analysis, IR, 1H NMR and mass spectra. The crystal structures of (C5H5FeC5H4CO2)2Sb(4‐CH3C6H4)3 and C5H5FeC5H4CO2SbPh4 were determined by X‐ray diffraction. Four human neoplastic cell lines (HL‐60, Bel‐7402, KB and Hela) were used to screen these compounds. The results indicate that these compounds at 10 µM show certain in vitro antitumor activities. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
8.
New Alkylchlorosulfonium Salts and Crystal Structure of Diethylchlorosulfonium-Hexachloroantimonate (C2H5)2SCl+SbCl6? We describe the preparation and spectroscopic characterization of Dialkylchlorosulfonium-Hexachloroantimonates R2SCl+SbCl6? (R = C2H5, i-C3H7) and the crystal structure of Diethylchlorosulfonium-Hexachloroantimonate (C2H5)2SCl+SbCl6? at 172(1) K. The salt crystallize in the orthorhombic space group P212121 with a = 980.4(13) pm, b = 1010.6(8) pm, c = 1492.8(14) pm with four formula units per unit cell. 相似文献
9.
David J. McAdoo Charles E. Hudson John C. Traeger 《Journal of mass spectrometry : JMS》1988,23(11):760-764
The distonic ions HO+?CHCH2C˙H2 (1) and CH3C(?O+H)CH2C˙H2 (2) were directly generated, their decompositions characterized and their appearance energies determined by photoionization. Heats of formation derived from the appearance energies were 757 kJ mol?1 for 1 and 692 kJ mol?1 for 2. Deuterium labeling demonstrates that both ions decompose at low energies in the same ways as their isomers with the same skeletal structures, consistent with proposals that 1 and 2 are intermediates in the decompositions of those systems. Surprisingly, the values of the translational energy releases accompanying the formation of CH3CO+ and C2H5CO+ from 2 appear to be inversely proportional to the available excess energy. The 1,2-H-shift RC(?O+H)CH2C˙H2 → RC(?O+H)C˙HCH3 is compared to the corresponding, non-occurring 1,2-H-shift in alkyl free radicals. 相似文献
10.
Tino Gumann Raymond Houriet Daniel Stahl Jean-Claude Tabet Nikolaus Heinrich Helmut Schwarz 《Journal of mass spectrometry : JMS》1983,18(5):215-218
The [C6H9]+ ions produced either via unimolecular H2O loss from 13 [C6H11O]+ precursors or direct protonation of 1,3- and 1,4-cyclohexadiene have identical collisional activation mass spectra. The kinetic energy release data for the process [C6H11O]+→[C6H9]++H2O are also very similar (on average T0.5=24 meV) irrespective of the constitution of the precursor. From the proton affinities of 1,3-cyclohexadiene (PA=837.2 kJ mol?1) using ion cyclotron resonance mass spectrometry the heat of formation of the [C6H9]+ ion is determined to 804.6 kJ mol?1. This value taken together with the results of molecular orbital calculations (MNDO) and the structure indicative losses of CH3. and C2H4 upon collisional activation suggest that the [C6H9]+ ion has the structure of the 1-methylcyclopentenylium ion f and not that of the slightly less stable cyclohexenylium ion g. The generator of an easily interconverting system of isomeric [C6H9]+ ions is unlikely to be due to the high barrier separating the various isomers. 相似文献
11.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(13):3154-3161
IR photodissociation spectra of mass‐selected clusters composed of protonated benzene (C6H7+) and several ligands L are analyzed in the range of the C? H stretch fundamentals. The investigated systems include C6H7+? Ar, C6H7+? (N2)n (n=1–4), C6H7+? (CH4)n (n=1–4), and C6H7+? H2O. The complexes are produced in a supersonic plasma expansion using chemical ionization. The IR spectra display absorptions near 2800 and 3100 cm?1, which are attributed to the aliphatic and aromatic C? H stretch vibrations, respectively, of the benzenium ion, that is, the σ complex of C6H7+. The C6H7+? (CH4)n clusters show additional C? H stretch bands of the CH4 ligands. Both the frequencies and the relative intensities of the C6H7+ absorptions are nearly independent of the choice and number of ligands, suggesting that the benzenium ion in the detected C6H7+? Ln clusters is only weakly perturbed by the microsolvation process. Analysis of photofragmentation branching ratios yield estimated ligand binding energies of the order of 800 and 950 cm?1 (≈9.5 and 11.5 kJ mol?1) for N2 and CH4, respectively. The interpretation of the experimental data is supported by ab initio calculations for C6H7+? Ar and C6H7+? N2 at the MP 2/6‐311 G(2df,2pd) level. Both the calculations and the spectra are consistent with weak intermolecular π bonds of Ar and N2 to the C6H7+ ring. The astrophysical implications of the deduced IR spectrum of C6H7+ are briefly discussed. 相似文献
12.
Irving Kuntz 《Journal of polymer science. Part A, Polymer chemistry》1967,5(1):193-203
The initiation process for the polymerization of tetrahydrofuran with (C6H5)3C+SbCl6? has been studied. Two mechanisms have been considered: a cation-addition process, and a process in which tetrahydrofuran donates a hydride ion to the cation of the initiator to form triphenylmethane. The biscarbonium salt [(C6H5)2C+C6H4CH2]2(SbCl6?)2 has been synthesized and used to initiate the polymerization of tetrahydrofuran. The results are consistent with the hydride-ion mechanism but may be inconclusive because of chain transfer. NMR experiments with 0.05–0.2M solutions of initiator in tetrahydrofuran show that triphenylmethane is rapidly produced in an amount equal to the molar amount of initiator originally present. Some NMR evidence for the presence of an acetal end group in the polymer has been obtained. It is concluded that the initiation process in this system definitely involves the formation of triphenylmethane, although a detailed, unique mechanism cannot be selected at this time. 相似文献
13.
Collisional activation spectra of [C8H8]+·, [C8H8]2+, [C6H6]+· and [C6H5]+ ions from fifteen different sources are reported. Decomposing [C8H8]+· ions of ten of these precursors isomerise to a mixture of mainly the cyclooctatetraene and, to a smaller extent, the styrene structure. Three additional structures are observed with [C8H8]+· ions from the remaining precursors. [C8H8]2+., [C8H8]+·, [C6H6]+· and [C6H5]+· ions mostly decompose from common structures although some exceptions are reported. 相似文献
14.
John L. Holmes Johan K. Terlouw Peter C. Burgers Robin T. B. Rye 《Journal of mass spectrometry : JMS》1980,15(3):149-151
Charge stripping (collisional ionization) mass spectra are reported for isomeric [C5H8]+˙ and [C3H6]+˙ ions. The results provide the first method for adequately quantitatively determining the structures and abundances of these species when they are generated as daughter ions. Thus, loss of H2O from the molecular ions of cyclopentanol and pentanal is shown to produce mixtures of ionized penta-1,3- and -1,4-dienes. Pent-1-en-3-ol generates [penta-1,3-diene]+˙. [C3H6]+˙ ions from ionized butane, methylpropane and 2-methylpropan-1-ol are shown to have the [propene]+˙ structure, whereas [cyclopropane]+˙ is produced from ionized tetrahydrofuran, penta-1,3-diene and pent-1-yne. 相似文献
15.
Unstable 2-hydroxpropene was prepared by retro-Diels-Alder decomposition of 5-exo-methyl-5-norbornenol at 800°C/2 × 10?6 Torr. The ionization energy of 2-hydroxypropene was measured as 8.67±0.05 eV. Formation of [C2H3O]+ and [CH3]+ ions originating from different parts of the parent ion was examined by means of 13C and deuterium labelling. Threshold-energy [H2C?C(OH)? CH3]+˙ ions decompose to CH3CO++CH3˙ with appearance energy AE(CH3CO+) = 11.03 ± 0.03 eV. Higher energy ions also form CH2?C?OH+ + CH3 with appearance energy AE(CH2?C?OH+) = 12.2–12.3 eV. The fragmentation competes with hydrogen migration between C(1) and C(3) in the parent ion. [C2H3O]+ ions containing the original methyl group and [CH3]+ ions incorporating the former methylene and the hydroxyl hydrogen atom are formed preferentially, compared with their corresponding counterparts. This behaviour is due to rate-determining isomerization [H2C?C(OH)? CH3]+˙ →[CH3COCH3]+˙, followed by asymmetrical fragmentation of the latter ions. Effects of internal energy and isotope substitution are discussed. 相似文献
16.
Detlef Schröder Katrin Schroeter Waltraud Zummack Helmut Schwarz 《Journal of the American Society for Mass Spectrometry》1999,10(9):878-882
Charge reversal (+CR−) of cations to anions can be used to structurally differentiate isomeric C6H5+ and C6H6+· hydrocarbon ions by means of tandem mass spectrometry. In view of the manifold of possible isomers, only a few prototype precursors are examined. Thus, charge inversion demonstrates that electron ionization of 2,4-hexadiyne yields an intact molecular ion, whereas the charge inversion spectra of C6H6+· obtained from benzene, 1,5-hexadiyne, and fulvene are identical within experimental error. Similarly, the +CR− spectrum of the C6H5+ cation generated by dissociative ionization of 2,4-hexadiyne is significantly different from the +CR− spectrum of C6H5+ obtained from iodobenzene, suggesting the formation of a 2,4-hexadiynyl cation from the former precursor. Although charge inversion of cations to anions has a low efficiency and requires large precursor ion fluxes, the particular value of this method is that the spectra may not just differ in fragment ion intensities, but these differences can directly be related to the underlying ion structures. 相似文献
17.
The dissociative spectrum of the [C6H5S]+ ion derived by charge inversion from [C6H5S]?, shows a variety of fragmentations including the competitive losses of H?, C3H4 and the formation of [CHS]+. The spectrum of a deuteriated derivative shows that these three processes are preceded or accompanied by H/D scrambling. The corresponding [C6H5O]+ species also undergoes hydrogen scrambling prior to fragmentation. In marked contrast, the ion [p-MeC6H4S]+ does not undergo hydrogen randomization between the methyl and aryl groups, and positional integrity is retained during fragmentation. These results are compared with the properties of the same ions produced by conventional ionization. 相似文献
18.
The kinetics of depletion of ground state Ti(a3F) and electronically excited state Ti(a5F) upon interactions with CH4, C2H2, C2H4, and C2H6 are studied in a fast-flow reactor at a He pressure of 0.70 Torr. No depletion of ground state Ti(a3F) was observed upon interaction with all hydrocarbons studied here. Two alkanes, CH4 and C2H6, were also quite inert for depletion of the excited state Ti(a5F), On the other hand, C2H2 and C2H4 deplete the excited state Ti(a5F) very efficiently. Rate constants were determined to be (266 ± 86) and (476 ± 88) × 10?12 cm3s?1 for Ti(a5F) + C2H4 and Ti(a5F) + C2H2, respectively. These large rate constants compared with the ground state Ti were explained by an electron donor-acceptor interaction model that works in the interaction between C2H4 or C2H2 and the excited state with unfilled 4s orbital. 相似文献
19.
Addition of methoxide to either geometric isomer of the benzylidene complex [(η-C5H5)Re(NO)(PPh3)(CHC6H5)]+PF6? (1t, 1k) affords (η-C5H5)Re(NO)(PPh3)(CH(OCH3)C6H5 (2t, 2k) in which a new chiral center has been generated stereospecifically or with high stereoselectivity. Reaction of 2t and 2k with Ph3C+PF6? results in the chemospecific abstraction of a methoxy group and the stereospecific regeneration of 1t and 1k, respectively. 相似文献
20.
《International journal of mass spectrometry and ion processes》1984,55(2):171-188
The structures of [C6H5]+ species, formed from a variety of precursors, have been investigated by ion/molecule reactivity studies with pulsed ion cyclotron resonance mass spectrometry and by collision spectroscopy with mass-analyzed ion kinetic energy spectrometry. Formed by sequential ion/molecule reactions in gaseous acetylene, the [C6H5]+ species are present as a mixture of isomers, those that react with acetylene and those that do not. Ion-assisted dehalogenation reactions were used to establish that the unreactive [C6H5]+ isomer was the phenylium ion. These data were used to study and confirm collisional decomposition reactions postulated to be diagnostic of the acyclic and phenylium isomers. These diagnostic reactions were then used to study the composition of the [C6H5]+ isomers produced by electron ionization of a number of precursors. These results are contrasted with previous studies and the collision spectroscopy experiments are described in detail. The possible role of [C6H5]+ species in flame processes is discussed. 相似文献