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Styrene energetics and characterization of its conjugate base: An example of isotopic labeling gone awry

Fattahi, A ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1016/j.ijms.2016.03.009
  3. Publisher: Elsevier
  4. Abstract:
  5. The equilibrium acidity of styrene was measured (δH°acid(PhCHCH2)=390.6±0.5kcalmol-1) and its deprotonation site was revised from the ortho position on the aromatic ring to the α-hydrogen atom based upon deuterium-labeling studies and extensive computations. Somewhat surprisingly, the nature of the anionic base plays a critical role in properly determining the ionization site and avoiding misleading results due to extraordinary hydrogen-deuterium exchange. Bracketing the electron affinity of α-styryl radical (PhC CH2, 23.1±3.4kcalmol-1) enabled the α-CH bond dissociation energy (100.1±3.4kcalmol-1) of styrene and the effect of a phenyl substituent at an sp2-hybridized carbon to be determined. These results were compared to B3LYP, M06-2X, G3 and G4 computations
  6. Keywords:
  7. Bond dissociation energy ; Gas-phase energetics ; Hydrogen-deuterium exchange ; Styrene ; α-Styryl radical
  8. Source: International Journal of Mass Spectrometry ; 2016 ; 13873806 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S138738061630015X