Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation

Büker H-H, Grützmacher H-F (2017)
EUROPEAN JOURNAL OF MASS SPECTROMETRY 23(6): 327-340.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Autor*in
Büker, Heinz-Hermann; Grützmacher, Hans-FriedrichUniBi
Abstract / Bemerkung
The reactions of the [2-2]-paracyclophane 1 and the [2-2]-metaparacyclopane 2 in the gas phase after protonation by CI(CH4) or CI(I-C4H10) were studied by FT-ICR mass spectrometry. The ions C16H17+ thorn produced in the external ion source of the FT-ICR instrument were transferred into the ICR cell containing the neutral reactant, and the reactions were analyzed measuring the efficiency of the transfer of a proton to a series of bases with known proton affinity and gas phase basicity as well as the efficiency of the ion-molecule reaction with ethyl vinyl ether. Both reaction types show that the ions C16H17+ thorn produced by chemical ionization (CI) consist of two sets of isomeric ions A and B which exhibit distinctly different behavior on deprotonation and of the reaction with ethyl methyl ether. Isomer(s) A (about 65% of the ion population) react efficiently with this vinyl ether by an addition/elimination process typical of primary and secondary benzylic carbenium ions, while isomer B (about 35% of the ion population) undergoes only an ineffective deprotonation by the vinyl ether. By bracketing deprotonation, it is shown that A is actually composed of two isomers A1 and A2 with slightly different proton affinity and gas phase basicity. These two ions have been identified using CA-mass spectrometry as protonated 3-phenethylstyrene (Al) and protonated 4-phenethylstyrene (A2). The CA-mass spectrum of the isomer B indicated that these ions C16H17+ thorn correspond to protonated 1-(ethyl phenyl)-1-phenyl-ethene. This agrees with the rather strong basicity of the conjugated base of ions B, which results in a slow deprotonation. A protonated 1-(ethyl phenyl)-1-phenyl-ethene can arise from a protonated 2-phenethylstyrene by H-and subsequent phenyl shifts, but requires the preceding rearrangement of the protonated [2.2]paracyclophane into the protonated isomer "[2.2]-orthocyclophane'' -the 1,5-dibenzocyclooctadiene. The possibility of such a deep-sited rearrangement was studied by the computation of the relevant reaction routes applying DFT-methods at the level B3LYP/6-311thorng(3d, 2p)//B3LYP/3-21g) to analyze the reaction mechanisms.
Stichworte
Cyclophanes; chemical ionization; mass spectrometry; FT-ICR; fragmentation; DFT computations
Erscheinungsjahr
2017
Zeitschriftentitel
EUROPEAN JOURNAL OF MASS SPECTROMETRY
Band
23
Ausgabe
6
Seite(n)
327-340
ISSN
1469-0667
eISSN
1751-6838
Page URI
https://pub.uni-bielefeld.de/record/2917743

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Büker H-H, Grützmacher H-F. Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation. EUROPEAN JOURNAL OF MASS SPECTROMETRY. 2017;23(6):327-340.
Büker, H. - H., & Grützmacher, H. - F. (2017). Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation. EUROPEAN JOURNAL OF MASS SPECTROMETRY, 23(6), 327-340. doi:10.1177/1469066717729537
Büker, H. - H., and Grützmacher, H. - F. (2017). Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation. EUROPEAN JOURNAL OF MASS SPECTROMETRY 23, 327-340.
Büker, H.-H., & Grützmacher, H.-F., 2017. Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation. EUROPEAN JOURNAL OF MASS SPECTROMETRY, 23(6), p 327-340.
H.-H. Büker and H.-F. Grützmacher, “Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation”, EUROPEAN JOURNAL OF MASS SPECTROMETRY, vol. 23, 2017, pp. 327-340.
Büker, H.-H., Grützmacher, H.-F.: Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation. EUROPEAN JOURNAL OF MASS SPECTROMETRY. 23, 327-340 (2017).
Büker, Heinz-Hermann, and Grützmacher, Hans-Friedrich. “Proton-induced reactions of [2.2]-paracyclophane in the gas phase. A study by FT-ICR-spectrometry and DFT calculation”. EUROPEAN JOURNAL OF MASS SPECTROMETRY 23.6 (2017): 327-340.

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