Didehydro radical anions from ketones via O− chemical ionization

Lin, Mingxiang; Grabowski, Joseph J.

doi:10.1016/j.ijms.2004.07.003

Cited by 11 publications

(15 citation statements)

References 38 publications

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“…The O •− + H 3 CCHO reaction products are indicated with red arrows and labels. Similar to the high-pressure flow-tube results, we observe the vinoxide anion, H 2 CCHO − ( m / z = 43 amu) and the formylmethylene anion, HCCHO •− ( m / z = 42 amu). In addition, we observe an m / z = 40 amu peak assigned to the ketenylidene anion, CCO •− .…”

Section: Experimental Results and Analysissupporting

confidence: 85%

“…The gas-phase reactivity of atomic oxygen radical anion (O •− ) with organic molecules is well documented. − This anion primarily reacts with organics via H + , H • , or H 2 •+ abstraction, as indicated by the respective reactions:These reactions are extremely useful, as they provide a convenient method for gas-phase synthesis of a number of important anion intermediates. These intermediates can be characterized by spectroscopy, reactivity, or fragmentation in order to obtain their thermochemical properties, as well as molecular and electronic structures.…”

Section: Introductionmentioning

confidence: 99%

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O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

2011

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The mass-resolved anionic products of the reaction of O(•-) with acetaldehyde, H(3)CCHO, are studied using photoelectron imaging. The primary anionic products are vinoxide, H(2)CCHO(-), formylmethylene anion, HCCHO(•-), and ketenylidene anion, CCO(•-). From photoelectron spectra of HCCHO(•-), the electron affinity of triplet (ground state) formylmethylene (1.87 ± 0.02 eV) and the vertical detachment energy corresponding to the first excited triplet state (3.05 eV) are determined, but no unambiguous assignment for singlet HCCHO could be made. The elusive singlet is a key intermediate in the Wolff rearrangement, resulting in formation of ketene. The fast rearrangement associated with a large geometry change upon photodetachment to the singlet surface may be responsible for the low intensity of the singlet compared to the triplet bands in the photoelectron spectrum. The title reaction also yields CCO(•-), whose formation from acetaldehyde is novel and intriguing, since it requires a multistep net-H(4)(+) abstraction. A possible mechanism is proposed, involving an [H(2)CCO(•-)]* intermediate. From the measured electron affinities of HCCHO (above), H(2)CCHO (1.82 ± 0.01 eV), and CCO (2.31 ± 0.01 eV), several new thermochemical properties are determined, including the C-H bond dissociation energies and heats of formation of several organic molecules and/or their anions. Overall, the reactivity of O(•-) with organic molecules demonstrates the utility of this anion in the formation of a variety of reactive intermediates via a single process.

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Section: Experimental Results and Analysissupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

2011

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“…24 Peak D (at 80 amu) corresponds to the ion of interest, i.e., the cyclopentadienone isomer of C 5 H 4 O − (as will become clear shortly). Peak C (81 amu) is consistent with the 13 C substituted version of the same anion, 13 1a). Although C 5 H 6 O − is expected to be adiabatically stable with respect to detachment (per CCSD/aug-cc-pVDZ calculations), it is only a minor product in the present case.…”

Section: Resultsmentioning

confidence: 73%

“…The nascent O •– then reacted with the cyclopentanone precursor, producing a variety of anionic species, including C 5 H 4 O – . The reactivity of O •– with closed-shell organic compounds is well documented and has been utilized to synthesize a number of important anion intermediates in the gas phase. − …”

Section: Experimental Methodsmentioning

confidence: 99%

Low-Lying Electronic States of Cyclopentadienone

2014

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We report a combined experimental and theoretical study of the low-lying electronic states of cyclopentadienone (C5H4O). The cyclopentadienone anion (C5H4O(-)) was generated in the gas phase via reaction of atomic oxygen radical anions (O(-)) with cyclopentanone (C5H8O). Photoelectron imaging was used to gain access to the first three electronic states of C5H4O, including the X (1)A1 ground state and the (3)B2 and (3)A2 excited states. The first two state assignments are supported by the Franck-Condon simulations of the vibrational progressions observed in the X (1)A1 and (3)B2 bands in the photoelectron spectra. The adiabatic electron affinity of cyclopentadienone in the ground state is determined to be EA(X (1)A1) = 1.06 ± 0.01 eV, and the corresponding values for the first two excited states are EA((3)B2) = 2.56 ± 0.02 eV and EA((3)A2) = 3.45 ± 0.01 eV. These experimental determinations are in excellent agreement with the CCSD(T) theory predictions, lending further confidence to the above state assignments. On the basis of these results, the lowest singlet-triplet splitting (between the X (1)A1 and (3)B2 states) in cyclopentadienone is ΔES-T = 1.50 ± 0.02 eV.

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“…With the pioneering work of Kenttämaa and coworkers as well as other researchers, numerous studies have been directed toward charge-inert radical cations [3,[6][7][8][9][10][11][12]. At the same time, the studies of distonic radical anions have also yielded interesting results [4,5,[13][14][15][16][17][18]. The fascinating benzyne radical anions were synthesized by Squires, Wenthold and coworkers in a flowing afterglow-triple quadrupole instrument.…”

Section: Introductionmentioning

confidence: 99%

Generation and characterization of distonic dehydrophenoxide radical anions under electrospray and atmospheric pressure chemical ionizations

Morishetti

Prabhakar

Vairamani

et al. 2011

International Journal of Mass Spectrometry

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Didehydro radical anions from ketones via O− chemical ionization

Cited by 11 publications

References 38 publications

O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

Low-Lying Electronic States of Cyclopentadienone

Generation and characterization of distonic dehydrophenoxide radical anions under electrospray and atmospheric pressure chemical ionizations

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Didehydro radical anions from ketones via O− chemical ionization

Cited by 11 publications

References 38 publications

O− + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

O− + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

Low-Lying Electronic States of Cyclopentadienone

Generation and characterization of distonic dehydrophenoxide radical anions under electrospray and atmospheric pressure chemical ionizations

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O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate

O⁻ + Acetaldehyde Reaction Products: Search for Singlet Formylmethylene, a Wolff Rearrangement Intermediate