1724-46-5Relevant academic research and scientific papers
Ion-Molecule Reactions of CF3+ with Simple Unsaturated Aliphatic Hydrocarbons at Near-Thermal Energy
Tsuji, Masaharu,Aizawa, Masato,Nishimura, Yukio
, p. 3195 - 3200 (2007/10/02)
Ion-molecule reactions of CF3+ with C2H2, C2H4, and C3H6 have been studied at near-thermal energy (0.05 eV) by using an ion beam apparatus.Initial product ion distributions and reaction rate constants were determined and compared with previous beam and selected ion flow tube (SIFT) data.The CF3+/C2H2 reaction produces exclusively the electrophilic adduct C3H2F3+ ion.For C2H4 and C3H6, hydride abstraction and electrophilic addition followed by HF elimination or fluoride transfer occur in parallel.The branching ratios of the former and latter reactions are 0.29 +/- 0.04:0.71 +/- 0.06 for the CF3+/C2H4 reaction and 0.07 +/- 0.02:0.93 +/- 0.07 for the CF3+/C3H6 reaction.On the basis of theoretical calculations of potential energies for the CF3+/C2H2 and CF3+/C2H4 systems, the lack of the HF elmination channel in the CF3+/C2H2 reaction, whereas the lack of the initial adduct ion in the CF3+/C2H4 reaction, is attributed to the different stability of the intermediate adduct ions for HF elimination.The reaction rate constants were 0.45 x 1E-9, 1.3 x 1E-9, and 1.6 x 1E-9 cm3 s-1 for C2H2, C2H4, and C3H6, respectively, which correspond to 46percent, 120percent, and 130percent of calculated rate constants from Langevin theory or a parametrized trajectory model.Although there are significant discrepancies in the product ion distributions between the present beam experiment and the previous beam data, the product ion distributions and the reaction rate constants obtained here are in reasonable agreement with the previous SIFT data.
Reduction of 1-Substituted 2,4,6-Triphenylpyridinium Ions in Aprotic Media
Joergensen, Lars Viborg,Lund, Henning
, p. 759 - 764 (2007/10/02)
Some 1-substituted 2,4,6-triphenylpyridinium salts have been studied by cyclic voltammetry.The compounds exhibit two or three reduction peaks depending on the sweep rate and the rate of loss of the 1-substituent.The rate of cleavage of the one-electron reduction product (the radical) was measured by cyclic voltammetry and double potential step chronoamperometry, and the rate of cleavage of the two-electron reduction product (the anion) found by simulation of the voltammetric curves; the simulation suggested that the rate of cleavage of the radical was faster than the rate of cleavage of the anion.This unexpected finding is tentatively explained by different conformations of the phenyl groups in the 2 and 6 positions in the radical and in the anion.
Gas-phase measurements of the kinetics of BF2(+)-induced polymerization of olefinic monomers
Forte, Leonard,Lien, Min H.,Hopkinson, Alan C.,Bohme, Diethard K.
, p. 1576 - 1583 (2007/10/02)
The initial steps in the BF2(+)-induced polymerization of the monomers of ethylene, propylene, cis-2-butene, isobutene, and styrene have been observed in the gas phase at room temperature using the Selected-Ion Flow Tube (SIFT) technique.Rate constants and product distributions have been determined for the initiation of the polymerization in each case.All five initiation reactions were found to be rapid (k >/= 5.0*10-10 cm3 molecule-1 s-1).The primary product ions that propagate polymerization have been identified and sequential addition reactions have been followed in all five systems.For ethylene the energetics of the initial steps have been followed using ab initio molecular orbital theory.Reaction of BF2+ with the vapours of water and benzene have also been characterized. Key words: ion-induced polymerization; alkenes; kinetics; gas phase ion chemistry
Selected-ion flow tube studies of reactions of the radical cation (HC3N)+. in the interstellar chemical synthesis of cyanoacetylene
Fox, A.,Raksit, A. B.,Dheandhanoo, S.,Bohme, D. K.
, p. 399 - 403 (2007/10/02)
The radical cation (HC3N)+. was produced in a Selcted-Ion Flow Tube (SIFT) apparatus from cyanoacetylene by electron impact and reacted at room temperature in helium buffer gas with a selection of molecules including H2, CO, HCN, CH4, H2O, O2, HC3N, C2H2, OCS, C2H4, and C4H2.The observed reactions exhibited a wide range of reactivity and a variety of pathways including charge transfer, hydrogen atom transfer, proton transfer, and association.Association reactions were observed with CO, O2, HCH and HC3N.With the latter two molecules association was observed to proceed close to the collision limit, which is suggestive of covalent bond formation perhaps involving azine-like N-N bonds.For HC3N an equally rapid association has been observed by Buckley et al. with ICR (Ion Cyclotron Resonance) measurements at low pressures and this is suggestive of radiative association.The hydrogen atom transfer reaction of ionized cyanoacetylene with H2 is slow while similar reactions with CH4 and H2O are fast.The reaction with CO fails to transfer a proton.These results have implications for synthetic schemes for cyanoacetylene as proposed in recent models of the chemistry of interstellar gas clouds.Proton transfer was also observed to be curiously unfavourable with all other molecules having a proton affinity higher than (C3N)..Also, hydrogen-atom transfer was inefficient with the polar molecules HCN and HC3N.These results suggest that informations at close separations may lead to preferential alignment of the reacting ion and molecule which is not suited for proton transfer or hydrogen atom transfer.
Gas-Phase Reactions of Anions with Substituted Silanes
DePuy, C. H.,Bierbaum, Veronica M.,Flippin, L. A.,Grabowski, Josef J.,King, Gary K.,et al.
, p. 5012 - 5015 (2007/10/02)
The gas-phase reactions of fluoride, amide, hydroxide, and methoxide ions with a variety of substituted silanes have been studied by the flowing afterglow technique.Fluoride reacts readily with trimethylsilyl derivatives to displace benzyl, alkenyl, and alkynyl anions.These reactions have also been used to generate specific structural isomers (CH3CC- and CH2C=C=CH-).Anions more basic than phenide ion cannot be produced in this manner, and their parent trimethylsilanes interact with fluoride by more complex mechanisms.Amide, hydroxide, and methoxide ions react with substituted trimethylsilanes by both displacement and proton abstraction whenever an acidic hydrogen is present; in the absence of displaceable groups and acidic hydrogen, the reactions of amide, hydroxide, and methoxide parallel those of fluoride ion.
