17333-73-2Relevant articles and documents
Mass-Spectrometric Study on Ion-Molecule Reactions of CF3+ with Nitrogen-Containing Benzene Derivatives, Pyridine, Pyrrole, and Acetonitrile at Near-Thermal Energy
Tsuji, Masaharu,Aizawa, Masato,Ujita, Hiroki,Nishimura, Yukio
, p. 2385 - 2392 (1995)
The gas-phase ion-molecule reactions of CF3+ with nitrogen-containing benzene derivatives (C6H5Y : Y = NH2, NO2, and CN), pyridine, pyrrole, and acetonitrile have been studied at near-thermal energy using an ion-beam apparatus.The major product channels are charge transfer for aniline (71.7 +/- 0.5), O- abstraction for nitrobenzene (91.7 +/- 0.5percent), electrophilic addition leading to initial adducts ions for benzonitrile (97.5 +/- 0.8percent), acetonitrile (100percent), and pyridine (94.8 +/- 0.4percent), and electrophilic addition followed by HF elimination for pyrrole (80.0 +/- 1.4percent).The reaction mechanism is discussed based on product ion distributions and theoretical calculations of the energies of reaction pathways.
Unimolecular Dissociation Rate Constants: Chlorobenzene Cations Revisited by Using a New Method
Stanley, R. J.,Cook, M.,Castleman, A. W.
, p. 3668 - 3674 (1990)
Unimolecular dissociation rates of metastable molecular ions formed at the laser focus of a time-of-flight mass spectrometer (TOFMS) have been determined by measuring the relative concentrations of parent metastable ions and the daugther fragment ions as a function of their retained kinetic energies upon dissociation.This is accomplished by the use of a simple one-stage ion mirror/energy analyzer.For a given reflection potential on the ion mirror, only those ions with a kinetic energy equal to or less than the reflection potential are detected.In this way, the relative concentrations of the parent and daughter ions as a function of their position of dissociation in the time-of-flight (TOF) lens can be measured, and consequently the dissociation lifetime can be derived.This technique has been applied to measuring the unimolecular dissociation rate of chlorobenzene ion (C6H5Cl+) in the three-photon energy range of 13.64-13.92 eV through resonance-enhanced two-photon state-selected ionization of chlorobenzene in a supersonic molecular jet.The method demonstrates a minimum dynamic range of 105 to 2*107 s-1 and is in good agreement with previous work.The data suggest that rotational temperature plays a role in the unimolecular dissociation lifetime of the metastable ions.
Infrared multiple-photon dissociation of the nitrobenzene radical cation. A paradigm for competitive reactions
Osterheld, Thomas H.,Baer, Tomas,Brauman, John I.
, p. 6284 - 6289 (1993)
The dissociation of nitrobenzene cation displays a variety of surprising and even apparently nonstatistical reaction behaviors. We have used infrared multiple-photon dissociation experiments to further study the reactions of this system. These experiments along with a previous photoelectron photoion coincidence study indicate that, for some products, the nitrobenzene cation dissociates to form an ion-neutral complex and then reassociates to give the phenyl nitrite cation. A reaction mechanism involving statistical dissociation is shown to account for the experimental data.
A combined theoretical and experimental study of the dissociation of benzene cation
Klippenstein, Stephen J.,Faulk, James D.,Dunbar, Robert C.
, p. 243 - 256 (1993)
Variational Rice-Ramsperger-Kassel-Marcus (RRKM) theory calculations of the energy and angular momentum dependence of the rate constant for the dissociation of C6H6+ into C6H5+ and an H atom are reported.In these variational calculations both the definition of the reaction coordinate and its value are independently optimized.A model potential-energy surface which interpolates between a Morse potential at short range and an ion-induced dipole potential at long range is employed in these variational calculations.The fully optimized variational results indicate that the transition state for this dissociation occurs at separation distances of about 3-4 Angstroem and that the available phase space in the transition state is typically a factor of 5 lower than the predicted by phase space theory.Experimental measurements were made of the time-resolved product ion intensity resulting from the laser-induced dissociation of a thermal (ca. 375 K) distribution of benzene cations.An ion cyclotron resonance trap was used over a range of photolysis wavelengths from 266 to 285 nm.The observed time dependences in the product ion signals are a result of both dissociative and radiative relaxation processes with a deconvolution procedure yielding estimated dissociation rate constants. Satisfactory agreement between the theoretical and experimental results, including the previous experimental results of Neusser and co-workers is obtained for an assumed dissociation energy of 3.88 eV to the lowest triplet state of C6H5+.
C6H5Br+? → C6H5+ + Br? occurs via orbiting transition state
Lim, Sang-Hyun,Choe, Joong Chul,Kim, Myung Soo
, p. 7375 - 7381 (1998)
Photodissociation of the bromobenzene molecular ion has been investigated on a nanosecond time scale by photodissociation mass-analyzed ion kinetic energy spectrometry. The rate constant and kinetic energy release distribution have been determined. The present experimental data together with the previous milli- to microsecond data have been compared with theoretical calculations. The rate-energy data available over 6 orders of magnitude in time scale could be fit with a nontotally loose transition state model (RRKM) reported by Rosenstock and co-workers. However, the model has been found to predict rate constant values larger than theoretically acceptable at high internal energy. The completely loose transition state model, namely the reaction occurring via orbiting transition state, seems to be a better description of the reaction.
On The Structure and Thermochemistry of the van der Waals Molecule C6H6*HCl and Its Photoion (C6H6*HCl)(1+)
Walters, E. A.,Grover, J. R.,White, M. G.,Hui, E. T.
, p. 3814 - 3818 (1985)
The dissociation energy of the van der Waals complex C6H6*HCl was determined to be 4.79 +/- 0.12 kcal mol-1 by measurement of the difference between the threshold for the dissociative photoionization of the complex and the ionization potential of C6H6.This value is compared to potential well depths obtained by analysis of centrifugal distortion constants for the same complex.The photoionization efficiency function for the production of (C6H6*HCl)(1+) from C6H6*HCl was obtained between 1280 and 1380 Angstroem.A weak threshold for direct ionization at 1357 +/- 7 Angstroem (9.14 +/- 0.05 eV) leads to a dissociation energy for (C6H6*HCl)(1+) of 7.3 +/- 1.2 kcal mol-1.The shape of the photoionization efficiency function is interpreted in terms of the involvement of the structure of the complex in the dissociation dynamics.Standard heats of formation are reported for C6H6*HCl (-10.4 kcal mol-1) and (C6H6*HCl)(1+) (204 kcal mol-1).
Molecular Beam Chemistry. Formation of Phenyl Cations from C6H5X Molecules
Safron, S.A.,King, G.A.,Horvat, R.C.
, p. 6333 - 6337 (1981)
Ractive scattering experiments between Cs(+) and C6H5X molecules with X=F, Br, I, and NO2 are reported and the results compared to previous experiments with X=Cl.The formation of the phenyl cation is discussed in terms of the intersections of two potentia
One-photon infrared photodissociation of polyatomic ions in a fast beam
Coggiola,Cosby,Helm,Peterson,Dunbar, Robert C.
, p. 2794 - 2800 (1987)
Photodissociation of 22 vibrationally excited polyatomic ions, ranging in size from four to thirteen atoms, has been observed following absorption of a single CO2-laser photon. In a number of cases the infrared wavelength dependence of the process shows well-defined peaking, which can be interpreted as absorption at the normal-mode frequencies of the ion. Kinetic energy release and order-of-magnitude fragmentation rate information have also been obtained for both photon-induced and metastable decomposition of a number of the ions. RRKM theory modeling indicates that these data are compatible with a quasi-equilibrium theory description of the unimolecular decomposition of highly vibrationally excited molecular ions. Considered as resulting from the last photon absorption of a multiphoton dissociation process, these results are relevant to understanding infrared multiphoton photochemistry of polyatomic molecules.
Dissociative proton transfer reactions of H3+, N2H+, and H3O+ with acyclic, cyclic, and aromatic hydrocarbons and nitrogen compounds, and astrochemical implications
Milligan, Daniel B.,Wilson, Paul F.,Freeman, Colin G.,Meot-Ner (Mautner), Michael,McEwan, Murray J.
, p. 9745 - 9755 (2007/10/03)
A flowing afterglow-selected ion flow drift tube has been used to measure the rate coefficients and product ion distributions for reactions of H3O+, N2H+, and H3+ with a series of 16 alkanes, alkenes, alkynes, and aromatic hydrocarbons as well as acrylonitrile, pyrrole, and pyridine. Exothermic proton transfer generally occurs close to the collision rate. The reactions of H3O+ are mostly nondissociative and those of H3+ are mostly dissociative, but many reactions, especially those of N2H+, have both dissociative and nondissociative channels. The dissociative channels result mostly in H2 and/or CH4 loss in the small hydrocarbons and in toluene, loss of C2H2 from acrylonitrile, and loss of HCN from pyrrole. Only nondissociative proton transfer is observed with benzene, pyridine, and larger aromatics. Drift tube studies of N2H+ reactions with propene and propyne showed that increased energy in the reactant ion enhances fragmentation. Some D3+ reactions were also investigated and the results suggest that reactions of H3+ with unsaturated hydrocarbons B proceed through proton transfer that forms excited (BH+)* intermediates. Pressure effects suggest that a fraction of the (BH+)* intermediates decomposes too rapidly to allow collisional stabilization in the flow tube (t -8 s). The other low-energy (BH+)* intermediates are formed by the removal of up to 40% of the reaction exothermicity as translational energy, and these intermediates result in stable BH+ products. The results suggest that, in hydrogen-dominated planetary and interstellar environments, the reactions of H3+ can convert C2-C6 hydrocarbons to smaller and less saturated molecules, but polycyclic aromatics are stable against decomposition by this mechanism. The dissociative reactions of H3+ can therefore favor the accumulation of small unsaturated hydrocarbons and aromatics in astrochemical environments.
