25453-90-1Relevant academic research and scientific papers
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.
Ion-Molecule Reactions and Thermal Decomposition of Ions in N2-O2-Alkane (C2-C8) Mixtures Studied by Time-Resolved Atmospheric Pressure Ionization Mass
Matsuoka, Shingo,Ikezoe, Yasumasa
, p. 1126 - 1133 (2007/10/02)
The experiments were carried out at temperatures ranging from 236 to 569 K.The O2+ ion reacted with n-alkanes (CnH2n+2) via fast nondissociative and dissociative charge-transfer channels, its proportion depending on temperature.The nondissociative product CnH(2n+2)+ subsequently reacted with O2 via a slow H atom transfer path, producing alkyl ions.With increasing temperature the alkane ions CnH(2n+2)+ (n >/= 4) began to decompose thermally, producing olefinic ions and alkanes.The product olefinic ions CmH2m+ (m=4,5,6) reacted with O2 via a slow H atom transfer path, producing alkenyl ions CmH(2m-1)+.The C8H17+ decomposed thermally forming fragment alkyl ions and olefins.The fragment alkyl ions reacted with n-C8H18 reproducing C8H17+, thus leading to a chain mechanism in n-C8H18 decomposition.The equilibrium reaction, C2H5+ + C2H6 ->/+, and the subsequent dissociative rearrangement reaction, C4H11+ -> C4H9+ + H2, were studied.The reactions of NO+ and NOO+, both minor products of the irradiation of N2-O2 mixtures, with alkanes were also studied.The rate constants of the ion-molecule reactions and the unimolecular thermal decomposition reactions and the equilibrium constant were measured.
