O- + acetaldehyde reaction products: Search for singlet formylmethylene, a Wolff rearrangement intermediate

Daniel J. Goebbert, Dmitry Khuseynov, Andrei M Sanov

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The mass-resolved anionic products of the reaction of O•? with acetaldehyde, H3CCHO, are studied using photoelectron imaging. The primary anionic products are vinoxide, H2CCHO?, 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-H4+ abstraction. A possible mechanism is proposed, involving an [H 2CCO•?]* intermediate. From the measured electron affinities of HCCHO (above), H2CCHO (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.

Original languageEnglish (US)
Pages (from-to)3208-3217
Number of pages10
JournalJournal of Physical Chemistry A
Volume115
Issue number15
DOIs
StatePublished - Apr 21 2011

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Acetaldehyde
acetaldehyde
Reaction products
reaction products
Anions
Photoelectrons
anions
Electron affinity
photoelectrons
electron affinity
thermochemical properties
Molecules
photodetachment
heat of formation
energy of formation
products
detachment
Excited states
Ground state
atomic energy levels

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

O- + acetaldehyde reaction products : Search for singlet formylmethylene, a Wolff rearrangement intermediate. / Goebbert, Daniel J.; Khuseynov, Dmitry; Sanov, Andrei M.

In: Journal of Physical Chemistry A, Vol. 115, No. 15, 21.04.2011, p. 3208-3217.

Research output: Contribution to journalArticle

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