Skeletal rearrangement of the methylcyclopentane ion. Field-ionization kinetic measurements

Falick, Arnold M.; Burlingame, Alma L.

doi:10.1021/ja00839a042

Cited by 18 publications

(1 citation statement)

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“…study (17) of methylcyclopentane-d3C Experiments on isomers of the hydrocarbons revealed that on the picosecond time scale, loss of methyl involved only the labelled group. At longer times S) loss of CH," and C,H, was preceded by ring opening and randomisation of C atoms.…”

Section: Introductionmentioning

confidence: 99%

Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening

Wolkoff¹,

Holmes²

1979

Can. J. Chem.

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Appearance energies and metastable peak shapes for methyl loss from the molecular ions of cyclohexene, methylcyclopentenes, methylenecyclopentane, bicyclo[3.1.0]hexane, and 2-methyl-1,4-pentadiene indicate that they have a common reaction pathway which produces [cyclopentenium]+ as the daughter ion at threshold.From measurements of appearance energies and from relative peak abundances and kinetic energy releases for the metastable losses of CH3• and labelled methyl from the deuterium labelled cyclic [C6H10]+• molecular ions it was concluded that: (a) H/D mixing in [cyclohexene]+• occurs in the intact ring prior to a concerted methyl extrusion; (b) [methylcyclopentenes]+• loses methyl without any H/D mixing at or near to threshold by a straight C—C cleavage, possibly via the 3-isomer. Methyl losses involving H/D mixing are preceded by ring opening which has an activation energy of ca. 1 eV. However, [cyclopentenium]+• is again the daughter ion; (c) methylenecyclopentane and bicyclo[3.1.0]hexane molecular ions isomerize to methylcyclopentenes prior to methyl loss.H/D mixing (prior to methyl loss) in the molecular ion 1,1-2H2-2-methyl-1,4-pentadiene takes place before cyclisation to methylcyclopentene.

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Section: Introductionmentioning

confidence: 99%

Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening

Wolkoff¹,

Holmes²

1979

Can. J. Chem.

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ChemInform Abstract: SKELETAL REARRANGEMENT OF THE METHYLCYCLOPENTANE ION, FIELD‐IONIZATION KINETIC MEASUREMENTS

Falick¹,

Burlingame²

1975

Chemischer Informationsdienst

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Mass Spectrometric Decomposition Processes in Labelled 1‐Heptenes

Falick

Gäumann

1976

Helvetica Chimica Acta

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Summary. The 70 eV mass spectra of a number of 1%-and D-labelled analogs of 1-heptene have been measured, as well as the metastable transitions in the non-labelled compound. Isotopic distributions in the major fragment ions have been calculated from the high and low resolution data. The results show that considerable skeletal rearrangement must take place before formation of most of the fragment ions. Loss of methyl and ethyl radicals occurs mainly from the two ends of the molecule. Ethylene fragments come primarily from the unsaturated end of the molecule, but show evidence of significant prior skeletal rearrangement. The predicted McLaffeerty rearrangement accounts for only 213 of the C4Hs+ ions formed, less for the C&a+ ions. At least 80% of C4H9+ ions appear to be formed by allylic cleavage, as expected, but this mechanism can only account for a maximum of 20% of the formation of the complementary ion C3H5+. Both, this latter ion and &Ha+, are probably generated by loss of hydrogen from CaH,+.Figures obtained for label retention in 1-[W]-and 1-D-labelled analogs were nearly identical for most fragment ions, probably indicating that the hydrogen atoms in position 1 remain on C(l) even following skeletal rearrangement. A similar result was found for the 7-[13C]-and 7-D-labelled compounds. The main exceptions in the case of the products labelled in position 1 (C4H7+, C3H3+) seem to be due to initial loss of an hydrogen atom from this position followed by further fragmentation.

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Skeletal rearrangement of the methylcyclopentane ion. Field-ionization kinetic measurements

Cited by 18 publications

References 7 publications

Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening

Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening

ChemInform Abstract: SKELETAL REARRANGEMENT OF THE METHYLCYCLOPENTANE ION, FIELD‐IONIZATION KINETIC MEASUREMENTS

Mass Spectrometric Decomposition Processes in Labelled 1‐Heptenes

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Skeletal rearrangement of the methylcyclopentane ion. Field-ionization kinetic measurements

Cited by 18 publications

References 7 publications

Isomeric cyclic [C6H10]+• ions. The energy barrier to ring opening

Isomeric cyclic [C6H10]+• ions. The energy barrier to ring opening

ChemInform Abstract: SKELETAL REARRANGEMENT OF THE METHYLCYCLOPENTANE ION, FIELD‐IONIZATION KINETIC MEASUREMENTS

Mass Spectrometric Decomposition Processes in Labelled 1‐Heptenes

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Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening

Isomeric cyclic [C₆H₁₀]^+• ions. The energy barrier to ring opening