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Styrene energetics and characterization of its conjugate base: An example of isotopic labeling gone awry
, Article International Journal of Mass Spectrometry ; 2016 ; 13873806 (ISSN) ; Lis, L ; Kass, S. R ; Sharif University of Technology
Elsevier
Abstract
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...
Styrene energetics and characterization of its conjugate base: An example of isotopic labeling gone awry
, Article International Journal of Mass Spectrometry ; Volume 413 , 2017 , Pages 163-167 ; 13873806 (ISSN) ; Lis, L ; Kass, S. R ; Sharif University of Technology
Elsevier B.V
2017
Abstract
The equilibrium acidity of styrene was measured (ΔH°acid(PhCH[dbnd]CH2) = 390.6 ± 0.5 kcal mol−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[rad][dbnd]CH2, 23.1 ± 3.4 kcal mol−1) enabled the α-C[sbnd]H bond dissociation energy (100.1 ± 3.4 kcal mol−1) of styrene and the effect of a phenyl substituent at an...