The origins of the base peak in the electron impact spectrum of limonene

Harris, Debi; McKinnon, Stewart; Boyd, Robert K.

doi:10.1002/oms.1210140507

Cited by 30 publications

(12 citation statements)

References 22 publications

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“…(a) is the mass peak at m/z 68. According to the work of Harris and coworkers, the ion m/z 68 is assigned to C 5 H 8 + , and the most probable mechanism of formation of C 5 H 8 + is inferred to be an isoprene unit resulting from a R‐DA reaction (Fig. S1).…”

Section: Resultsmentioning

confidence: 99%

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Photoionization and dissociation of the monoterpene limonene: mass spectrometric and computational investigation

et al. 2011

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The photoionization of the monoterpene limonene has been studied using tunable vacuum ultraviolet synchrotron radiation in the region from the threshold for ionization of the parent molecule up to 15.5 eV. The adiabatic ionization energy of limonene is derived from photoionization efficiency spectrum and found to be 8.27 eV, compared with the density functional theory calculations which yields a value of 8.08 eV (B3LYP/6-311++G). Primary dissociation pathways of the parent molecule ions are investigated by experimental observations and theoretical calculations. Most of the fragmentation channels occur via a rearrangement reaction prior to dissociation. Transition structures and intermediates for those isomerization processes are also determined.

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Section: Resultsmentioning

confidence: 99%

“…Our derived experimental value for the adiabatic IE of R‐(+) limonene (C 10 H 16 ) is 8.27 eV (Fig. (a)), which is excellent agreement with the earlier EI result of Harris et al , 8.30 eV. Garcia et al also report the vertical IE of 8.55 eV from their TPES .…”

Section: Resultsmentioning

confidence: 99%

Photoionization and dissociation of the monoterpene limonene: mass spectrometric and computational investigation

et al. 2011

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“…The ion-chemistry of monoterpenes has been studied by a number of experimental methods such as electron ionization [2,3], varying the ion source temperature [2,4], photoelectron spectroscopy [5][6][7], field ionization [8], collision-induced-dissociation [2,9], surface-induceddissociation [2], isotope labeling [10,11], metastable ion spectroscopy [11][12][13], and charge-stripping spectroscopy [14]. Thomas and Willhalm [15] recorded the electron impact mass spectra of 30 monoterpenes and proposed fragmentation mechanisms.…”

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confidence: 99%

“…Thomas and Willhalm [15] recorded the electron impact mass spectra of 30 monoterpenes and proposed fragmentation mechanisms. The fragmentation mechanisms for terpene ions may involve extensive scrambling and rearrangements and therefore at best are tentative [10,11].…”

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confidence: 99%

Bimolecular and unimolecular contributions to the disparate self-chemical ionizations of α-Pinene and camphene isomers

Solouki

Szulejko

2007

J. Am. Soc. Mass Spectrom.

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The contributions of molecular and fragment ions toward the disparate self-chemical ionization (SCI) of ␣-pinene and camphene isomers were investigated. A kinetic model was ␣ constructed to predict the SCI outcomes for these two C 10 H 16 isomers. A major portion of the camphene molecular ions (isolated 500 ms after the 10 ms EI event at 24 eV) unimolecularly dissociated within 200 s of the ionization event. Conversely, under similar experimental conditions, the ␣-pinene molecular ions as well as the major fragment ions of ␣ ␣-pinene and ␣ camphene showed no unimolecular dissociation. The ␣-pinene and camphene molecular ions ␣ yielded product ions through two different reaction mechanisms (direct charge-transfer {CT} and indirect proton transfer {PT}). The isolated terpene fragment ions at m/z 93 and 121 reacted with their respective neutrals to produce [M ϩ H] ϩ . Proton affinity (PA) bracketing experiments, PA additivity schemes, and alkene PA versus adiabatic ionization energy (IE) linear correlation indicated that the PAs of camphene and ␣-pinene were comparable ( ␣ ϳ210 Ϯ 2 kcal · mol Ϫ1 ). The observed [M ϩ H] ϩ SCI terpene ions were mainly the products of various fragment ion reactions. (J Am Soc Mass

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“…It has been a subject of interest for several years and is useful in structural elucidation of organic molecules which contain a double bond in a six-membered ring. '- 15 One of the more interesting questions concerning these RDA reactions is whether a stepwise or concerted mechanism is followed. Mandelbaum and coworkers have reported the probability that the RDA reaction depends upon the stereochemistry of the ring junction in tri-, tetra-and penta-cyclic diketones, with the cis isomers greatly On this basis, they conclude that the molecular ions decompose by a concerted pathway.…”

Section: Introduci'ionmentioning

confidence: 99%

A study of the electron impact induced retro‐diels‐alder process with selected 5,6,6a, 7,12,12a‐hexahydrobenzo[a]anthracenes

Bobenrieth

Levy

Hass

1984

Org. Mass Spectrom.

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The mass spectra of 5,6,6a,7,l2,l2a-herrabychobenzo[alanthr and 2-methoxy, 3-methoxy-, 4-methoxy and 1-methyl-6methoxy derivatives are reported. Among the fragment ions observed under electron impact ionization, [ a ] ' ' and ma]+* am be generated by a retro-DiebAlder process. Studies of metastable ion reactions show these ions to be formed by fragmentation directly from the molecular ion. The CA spectra of the [CJ&]+' ions from the subject compounds were compared with spectra fmm ions of the same composition from various sources. From these data, kinetic energy release measurements and stereochemical considerations, it is concluded that these ions are formed by a stepwise, rather than a concerted mechanism.

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The origins of the base peak in the electron impact spectrum of limonene

Cited by 30 publications

References 22 publications

Photoionization and dissociation of the monoterpene limonene: mass spectrometric and computational investigation

Photoionization and dissociation of the monoterpene limonene: mass spectrometric and computational investigation

Bimolecular and unimolecular contributions to the disparate self-chemical ionizations of α-Pinene and camphene isomers

A study of the electron impact induced retro‐diels‐alder process with selected 5,6,6a, 7,12,12a‐hexahydrobenzo[a]anthracenes

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