Barkow, Anja; Pilotek, Steffen; Gruetzmacher, Hans-Friefrich published the artcile< Ortho effects: a mechanistic study>, Product Details of C19H34O2, the main research area is fragmentation alkylbenzene derivative ortho effect; MIKE spectra alkylbenzene derivative; kinetic energy release MIKES alkylbenzenes.
The fragmentation mechanism in the loss of a water mol. from the radical cations of 2-methylbenzyl alc., 2-methylbenzoic acid, and some related compounds by an ortho effect is studied. The anal. of the MIKE spectra together with specific deuterium labeling studies and assisted by semiempirical calculations reveal a continuous spectrum of mechanisms of the ortho effect ranging from a two-step mechanism with a rate determining final loss of the neutral fragment and a rate determining 1,5-hydrogen transfer in the first step entailing a large activation energy to a presumably concerted 1,4-elimination with a more or less asym. high energy transition state. These mechanisms cause a different behavior of metastable ions with respect to the kinetic energy release (KER) during the fragmentation by an ortho effect. In case of a rate determining last step as established for the 1,4-elimination of NH3 from the mol. ions of 2-methylbenzylamine, the absence of a reversed activation energy ensures “”normal”” KER behavior and narrow Gaussian shaped peaks in the MIKE spectra. The other mechanisms of the ortho effect exhibit a significant reverse activation energy originating in a barrier to the initial 1,5-hydrogen transfer of the ortho effect. Consequently, large values of the KER are observed for this elimination process in the MIKE spectra of the precursor ions. However, the kinetic energy release distribution (KERD) during the dissociation depends on the stability of the intermediate distonic ion created by the 1,5-hydrogen migration. A well-defined and stable distonic ion as an intermediate leads to flat topped peaks and a large KER which is typically observed for the elimination of H2O in the MIKE spectra of the mol. ions of 2-methylbenzyl alc. and related 2-alkylbenzyl alcs. In the case of very short lifetime of the intermediate ion generated by the initial 1,5-hydrogen shift the mechanism cannot be distinguished from a concerted 1,4-elimination of H2O with a more or less asym. transition state. This situation is typical for the fragmentation of ionized 2-methylbenzoic acid and related 2-alkylbenzoic acids, and a broad, nearly triangular signal is observed in the MIKE spectrum of these mol. ions.
European Mass Spectrometry published new progress about Fragmentation reaction. 112-63-0 belongs to class esters-buliding-blocks, and the molecular formula is C19H34O2, Product Details of C19H34O2.
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