Butane ions, decomposition

In later work by Haag and Dessau product selectivity data were provided for n-butane cracking at 426-523 °C over HZSM-5 with Si/Ah = 70 [90]. The selectivity results at 496 °C and 1-10 kPa for n-butane were extrapolated to zero percent conversion in Table 13.6 to be able to identify the primary products and to assess the decomposition pattern of the n-butyl carbonium ion. Similar selectivities to methane and propylene implied, as expected, that the decomposition of the car-... 

Ion lifetimes from nanoseconds down to microseconds have been determined in experiments involving ionization within the confines of a molecular beam and decomposition within a strong electric field [381, 667, 672]. Using electron impact ionization, rates of decomposition have been determined as a function of time over the range 3 ns to 1 p s for ions formed from butane, heptane, perdeuteromethane, benzene, carbon dioxide and benzonitrile. 

Undoubtedly, it seems plausible that the large difference observed in the CH3T yield from the protonation of butane (15%) and isobutane (23%) reflects the higher probability that a carbonium ion protonated on a primary carbon is formed from the attack of HeT+ on isobutane. The decomposition of the intermediate according to equation 52 represents a direct route to tritiated methane ... 

The effect of electrical fields on the radiolysis of ethane has been examined by Ausloos et and this study has shown that excited molecules contribute a great deal to the products. The experiments were conducted in the presence of nitric oxide, and free-radical reactions were therefore suppressed. The importance of reactions (12)-(14) was clearly demonstrated by the use of various isotopic mixtures. Propane is formed exclusively by the insertion of CH2 into C2H6 and the yield is nearly equal to the yield of molecular methane from reaction (14). Acetylene is formed from a neutral excited ethane, probably via a hot ethylidene radical. Butene and a fraction of the propene arise from ion precursors while n-butane appears to be formed both by ionic reactions and by the combination of ethyl radicals. The decomposition of excited ethane to give methyl radicals, reaction (15), has been shown by Yang and Gant °° to be relatively unimportant. The importance of molecular hydrogen elimination has been shown in several studies ° °. ... 

Kinetics of decomposition at short times (methyl radical from the n-butane [825], 2, 2-dimethylbutane [240] and 2, 2-dimethylpentane [240] ions, loss of ethyl from n-heptane, n-hexane and n-octane ions [522, 825], loss of methane from the neopentane ion [825], and loss of ethane from the 3-ethylpentane ion... 

The /-butane chemical ionization spectra of benzyl acetate and t-amyl acetate have been investigated at a number of temperatures, and the rate constants for the decomposition of the protonated esters to benzyl and r-amyl ions, respectively, have been obtained at the several temperatures from (41) to (42). It is found that the rate constants obey the Arrhenius relationship, and this is illustrated in Fig. 5. Activation energies and frequency factors obtained from the Arrhenius plots are given in Table XIV. 

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