Bimolecular Reactions of Trapped Ions. VIII. Reactions in Propane and Propane–Methane Mixtures

Solka, B.H.; Lau, Andrew Y.-K.; Harrison, Alex G.

doi:10.1139/v74-258

Cited by 10 publications

(4 citation statements)

References 3 publications

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“…Gas-phase protonation of n -butane with small electrophiles, such as H 3 + 31 and CHO + , show, in general, the following reactivity order: primary C−C > secondary C−C > secondary C−H > primary C−H. Calculations are in agreement with these results, predicting the preferred protonation of C−C bonds in comparison to C−H bonds.…”

Section: 3 Discussionsupporting

confidence: 61%

The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane

et al. 2000

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The structure and energetics of the n-butonium ion, the protonated form of n-butane, were computed at the MP4SDTQ(fc)/6-311++G**//MP2(full)/6-31G** level. Eleven stable structures were found for the n-butonium ion, following the stability order 2-C-n-butonium > 1-C-n-butonium > 2-H-n-butonium > 1-H-n-butonium. The transition states for intramolecular bond-to-bond rearrangement and for decomposition of the carbonium ions into the van der Waals complexes were also calculated. The H-n-butonium and the 1-C-n-butonium ions are higher in energy than the van der Waals complexes 13, 14, and 15. The van der Waals complexes between the isopropyl cation plus CH 4 and the tert-butyl cation plus H 2 are the most stable C 4 H 11 + species. It was concluded that the 1-H-n-butonium ion prefers to undergo intramolecular rearrangement to the 1-C-n-butonium ion, whereas the 2-H-n-butonium ion prefers to decompose into the van der Waals complex of the sec-butyl cation plus H 2 . The calculated proton affinity of n-butane (156.7 kcal/mol) agrees well with the experimental value of 153.7 kcal/mol. The C 4 H 11 + (b) species, formed upon the gas-phase reaction between C 2 H 5 + and ethane, was confirmed to be the 2-C-n-butonium cation, and the C 4 H 11 + (a) species was confirmed to be the 2-H-n-butonium cation, as proposed by Hiraoka and Kebarle (Can. J. Chem. 1980Chem. , 58, 2262Chem. -2270. The experimental activation energy of 9.6 kcal/mol was compared with the value of 12.8 kcal/mol, computed for the reaction 11 f 5 through the transition state 21.

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Section: 3 Discussionsupporting

confidence: 61%

The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane

et al. 2000

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“…We have observed an apparent reaction to give C3H7+ in impure samples of C2H6 and attribute the observation to a fast reaction with C3H8 impurity. 33 No ejection signals for this reaction were evident for very pure ethane samples.…”

Section: Resultsmentioning

confidence: 95%

Product distributions and rate constants for the reactions of CH3+, CH4+, C2H2+, C2H3+, C2H4+, C2H5+, and C2H6+ ions with CH4, C2H2, C2H4, and C2H6

Kim¹,

Anicich²,

Huntress³

1977

J. Phys. Chem.

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Publication costs assisted by the Jet Propulsion Laboratory Ion cyclotron resonance methods have been used to measure the product distributions and rate constants for the reactions of various CH"+ and C2H"+ ions with CH4, C2H2, C2H4, and C2H6. The product distributions for some of the reactions of C2H2+, C2H4+, and C2H6+ ions are strongly affected by excess ion internal energy.Photoionization mass spectrometer experiments have been conducted in a few cases in order to obtain product distributions for reactions of these ions in the ground vibronic state.

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“…The values are summarized in TableI. Again the Journal of the American Chemical Society / 98:20 / September29, 1976…”

mentioning

confidence: 99%

Stabilities and energetics of pentacoordinated carbonium ions. The isomeric protonated ethane ions and some higher analogs: protonated propane and protonated butane

Hiraoka¹,

Kebarle²

1976

J. Am. Chem. Soc.

144

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The kinetics and equilibria of reaction 1 were studied in H2 gas at 1-5 Torr over the temperature range -160 to 200 °C. The experiments were done in a pulsed electron beam high pressure ion source mass spectrometer. At the lowest temperatures (-160 to -130 °C) reaction 1 reached equilibrium. The forward rate of (1) decreased with increasing temperature. This means that the C2H7+(a) formed at this temperature was a result of an exothermic third body dependent reaction without activation energy. Measurement of the temperature dependence of the equilibrium led to AH]a = -4.0 kcal/mol and A//KC2H7+(a)) = 215 kcal/mol. At temperatures above -130 °C, where C2H7+(a) was unstable, little C2H7+ could be observed. Between -100 and 40 °C a new species C2H7+(b) was formed by a second-order process (reaction lb). The rate constant /fcib for this reaction increased with temperature. The activation energy was E\b = 1.2 kcal/mol. At temperatures between 40 and 200 °C, C2H7+(b) began to decompose to C2H5+ + H2 and an equilibrium (reaction lb) could be measured giving AHib = -11.8 kcal/mol and AEff(C2H7+(b)) = 207 kcal/mol. The C2H7(a) is identified with the C-H protonated ethane structure A which, however, is very close to an undisturbed ethyl ion and an H2 molecule. The more stable structure C2H7+(b) is identified as B, the C-C protonated structure of ethane. The energy barrier between species (a) and (b) is E\b -AHia = 5.2 kcal/mol. Earlier results on the species C3H9"1" are combined with new measurements to establish the energetics of two experimental species CsHg+fa) which corresponds essentially to iec-C3H7+ interacting very weakly with H2 and the C3H9+(b) species of a structure similar to B. The heats of formation are A//f(C3H9+(a)) = 189.5 kcal/mol and A//f(C3H9+(b)) = 194.5 kcal/mol. Thus for the propanes the (a) species has the lower heat of formation. However, the (b) species is more stable with respect to dissociation. The potential energy barrier between C3H7+(a) and C3H7+(b) is ~14 kcal/mol. Two analogous structures for C4Hn+ are also investigated. Proton affinities for protonatioh to the respective isomers are also derived.The pentacoordinated methonium ion CH5"1" was among the first ion-molecule reaction products observed with mass spectrometers.1 The next higher analogue C2H7+ was also observed relatively early.2 However, until recently no clear experimental evidence for the existence and stability of higher protonated alkanes was available.The bonding in CH5"1" was considered in several theoretical papers3™8 which ultimately agreed on the three center-bonded structure with Cs symmetry shown below as being the most stable. Ab initio calculations4 (STO-3G) for the C2H7+ ion predicted two stable isomers, the C-H protonated structure (A) and the C-C protonated structure (B) shown below. The ° .structure (B) was found4 more stable by some 10-12 kcal/mol. However, more recently results obtained with the simpler semiempirical9 MINDO/3 predicted structure (A) to be more stable. More accurate ab initio calculations wit...

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Bimolecular Reactions of Trapped Ions. VIII. Reactions in Propane and Propane–Methane Mixtures

Cited by 10 publications

References 3 publications

The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane

The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane

Product distributions and rate constants for the reactions of CH3+, CH4+, C2H2+, C2H3+, C2H4+, C2H5+, and C2H6+ ions with CH4, C2H2, C2H4, and C2H6

Stabilities and energetics of pentacoordinated carbonium ions. The isomeric protonated ethane ions and some higher analogs: protonated propane and protonated butane

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Bimolecular Reactions of Trapped Ions. VIII. Reactions in Propane and Propane–Methane Mixtures

Cited by 10 publications

References 3 publications

The n-Butonium Cation (n-C4H11+): The Potential Energy Surface of Protonated n-Butane

The n-Butonium Cation (n-C4H11+): The Potential Energy Surface of Protonated n-Butane

Product distributions and rate constants for the reactions of CH3+, CH4+, C2H2+, C2H3+, C2H4+, C2H5+, and C2H6+ ions with CH4, C2H2, C2H4, and C2H6

Stabilities and energetics of pentacoordinated carbonium ions. The isomeric protonated ethane ions and some higher analogs: protonated propane and protonated butane

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The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane

The n-Butonium Cation (n-C₄H₁₁⁺): The Potential Energy Surface of Protonated n-Butane