20813-12-1Relevant articles and documents
Reactions of CH3+ with C2N2, CH2CHCN, and HC3N: A low-pressure/high-pressure study
McEwan,Fairley,Scott,Anicich
, p. 4032 - 4037 (1996)
The association of CH3+ with the three molecules C2N2, CH2CHCN, and HCCCN has been examined using ion cyclotron resonance (ICR) and selected ion flow tube (SIFT) techniques at room temperature. In each reaction, the mean lifetime of the complex (CH3·N≡C-R+)* formed in the association has a major influence on the outcome of the reaction and the product channels that are observed using ICR and SIFT. Termolecular rate coefficients are reported for the association of CH3+ + C2N2 for the bath gases M = He, Ar, N2, and C2N2. k3 = 8.2 × 10-24 cm6 s-1 (M = C2N2). In each system the association product channel occurs in competition with exothermic bimolecular channels. The complex lifetimes in all three systems are in the range 30-70 μs. Very rapid ion-molecule association reactions have been observed in several systems of hydrocarbons and nitriles, and the implications for Titan ion chemistry are discussed briefly.
Association Reactions at Low Pressure. 2. The CH3+/CH3CN System
McEwan, Murray J.,Denison, Arthur B.,Huntress, Wesley T. Jr.,Anicich, Vincent G.,Snodgrass, J.,Bowers, M. T.
, p. 4064 - 4068 (2007/10/02)
The reaction between CH3+ and CH3CN has been examined at pressures between 8E-8 and 1E-3 Torr in an ion cyclotron resonance mass spectrometer.At low pressures the reaction is bimolecular, having a rate coefficient of 1.8E-9 cm3s-1.The major ion products are H2CN+ and C2H5+, but a bimolecular association channel also competes with these two main binary exotermic channels.At pressures above ca. 4E-5 Torr the termolecular associaton (CH3CNCH3+) reaction becomes the major reaction.The results are rationalized in terms of barriers on the potential energy surface of the binary exit channels.The rate coefficient observed for the termolecular associaton reaction CH3+ + CH3CN + M CH3CNCH3+ + M was found to be k=1.90E-22 cm6 s-1 when M=CH3CN, and when M=N2, Ne, and He, k=4.0E-23, 0.6E-23, and 1.0E-23 cm6 s-1 respectively.The lifetime of the collision complex was found to be >14 μs.
Gas-phase Protonation and Methyl Cation Transfer from Methyl Halide Ions
Houriet, R.,Rolli, E.,Flammang, R.,Maquestiau, A.,Bouchoux, G.
, p. 770 - 774 (2007/10/02)
The ion-molecule reactions between +., +, + ions (X = F, Cl, Br, I) and a number of nucleophiles have been studied by ion cyclotron resonance techniques.Protonation of the nucleophiles is observed to occur from both the molecular ions X+. and protonated species + whereas dimethylalonium ions + react principally by methyl cation transfer.A notable exception occurs in methyl iodide where the molecular ions +. act both as proton and methyl cation donors, whereas dimethyliodonium ions are found unreactive.The results are discussed with reference to the use of alkyl halides as reagent gases in chemical ionization experiments.
Proton Affinities and Photoelectron Spectra of Three-Membered-Ring Heterocycles
Aue, Donald H.,Webb, Hugh M.,Davidson, William R.,Vidal, Mariano,Bowers, Michael T.,at al.
, p. 5151 - 5157 (2007/10/02)
Proton affinities and photoelectron spectra have been measured for azirane, phosphorane, oxirane, and thiirane and for the corresponding dimethylamine, phosphine, ether, and sulphide.The photoelectron spectra have been fully assigned by the use of ab initio STO-431G calculations and structural correlations within these series of molecules.The lone-pair ionization potentials of the heterocycles are higher than those of their open-chain dimethyl analogues because of charge redistribution effects in the C-X bonds and increased lone-pair's character in azirane and phosphirane.The proton affinities are lower in the heterocycles than in their dimethyl analogues as a result of increases in lone-pair's character and, especially for phosphirane, an increase in the RXR angle strain on protonation.Ab initio calculations on the protonated heterocycles and XHn models are presented to help interpret the proton-affinity data.
