26811-28-9Relevant articles and documents
Threshold Formation of Benzylium (Bz+) and Tropylium (Tr+) from Toluene. Nonstatistical Behavior in Franck-Condon Gaps
Lifshitz, Chava,Gotkis, Yehiel,Laskin, Julia,Ioffe, Alexander,Shaik, Sason
, p. 12291 - 12295 (1993)
Benzylium (Bz+) and tropylium (Tr+) ion formation from toluene-h8 and toluene-α-d3 were studied by time-resolved photoionization mass spectrometry (TPIMS).Bz+ was distinguished from Tr+ through its ion/molecule reaction with toluene, which converts it quantitatively to C8H9+.The appearance energies (AE's) at 0 K of C7H7+ without ion trapping (11.5 eV) and of Bz+ with ion trapping (11.1 eV) are in excellent agreement with predictions by time-resolved photodissociation (TRPD).The structure observed at photon energies below 11.1 eV in the Bz+ photoionization efficiency curve is ascribed to autoionizing Rydberg states converging to the third ionization energy in toluene.These states, which reside in a Franck-Condon gap, dissociate in competition with autoionization.This dissociation is a non-RRKM process forming Bz+, in preference to Tr+, and is made possible energetically by virtue of the thermal energy at the temperature of the experiment (298 K).H/D loss ratios for toluene-α-d3 demonstrate complete isotopic scrambling and an energy dependent isotope effect.The H/D ratio stays constant below 11.1 eV, demonstrating that AE0 K (Tr+) = 11.1 eV and that there is equality of the AE's of the two C7H7+ isomers within experimental error.The preferential, nonstatistical, formation of Bz+ over Tr+ below ca. 11.1 eV is given further proof by the observation of an increased direct CD2+ transfer probability from C6H5CD2+ to C6H5CD3.These results, combined with previously published ab initio calculations which demonstrated a reverse activation energy for the Tr+ exit channel, explain why there is no energy range in which there is pure Tr+ formation from toluene, under either photoionization or electron ionization conditions, although Tr+ is ca. 11 kcal/mol more stable than Bz+.
Time-Resolved Photodissociation Rates and Kinetic Modeling for Unimolecular Dissociations of Iodotoluene Ions
Lin, Chuan Yuan,Dunbar, Robert C.
, p. 1369 - 1375 (1994)
Time-resolved photodissociation rate measurements are reported for the unimolecular dissociation of the three iodotoluene ion isomers at two values of internal energy (2.54 and 2.67 eV).For the para isomer, the rate constants are in agreement with previous experimental information.The meta isomer is roughly similar to para, but the ortho isomer dissociates roughly 5 times faster at the same internal energies.These new data, along with prior results, are fitted into a comprehensive two-channel model of the dissociation kinetics, assuming competitive dissociation to form tolyl ions, and either benzyl or tropylium ions.Activation energies and entropies are assigned to both dissociation channels for each isomer.This two-channel model accounts satisfactorily for most of the experimental information available about these dissociation processes, and possible explanations are advanched to explain discrepant data.
Reaction of O2+ + C8H10 (ethylbenzene) as a function of pressure and temperature: A study of the collisional stabilization of the reactant intermediate
Viggiano,Miller, Thomas M.,Williams, Skip,Arnold, Susan T.,Seeley, John V.,Friedman, Jeffrey F.
, p. 11917 - 11922 (2007/10/03)
Rate constants and branching fractions for the reaction of O2+ with C8H10 (ethylbenzene) have been measured in the recently upgraded turbulent ion flow tube (TIFT) and are reported here as a function of temperat
Site of Gas-phase Methylation of 1-Phenyl-2-aminopropane
Zappey, Herman,Fokkens, Roel H.,Ingemann, Steen,Nibbering, Nico M. M.,Florencio, Helena
, p. 587 - 594 (2007/10/02)
The regioselectivity of methyl cation transfer from (CH3)2F(1+), (CH3)2Cl(1+) and (CH3)3O(1+) to 1-phenyl-2-aminopropane was studied by Fourier transform ion cyclotron resonance in combination with collision-induced dissociation and neutralization-reionization mass spectrometry of the stable (1+) ions formed in a chemical ionization source.The (CH3)2F(1+) ion transfers a methyl cation to the NH2 group and the phenyl ring with almost equal probability.Predominant CH3(1+) transfer to the NH2 group is observed for the (CH3)2Cl(1+) ion whereas the (CH3)3O(1+) ion reacts almost exclusively at the amino group.The preference for m ethylation at NH2 is discussed in terms of a lower methyl cation affinity of the phenyl ring than of the amino group and the existence of an energy barrier for methylation of the phenyl moiety.
