Dynamics of the dimethyl sulfide exchange of (1,3‐diphenylallyl)dimethylsulfonium ions

Jüstel, Patrick M. ; Rovó, Petra ; Mayr, Herbert und Ofial, Armin R. (2022): Dynamics of the dimethyl sulfide exchange of (1,3‐diphenylallyl)dimethylsulfonium ions. In: Journal of Physical Organic Chemistry, Bd. 35, Nr. 11

Abstract

The dynamics of the allylic rearrangement of the (1,3-diphenylallyl)dimethylsulfonium ion in CD2Cl2, which proceeds via intermediate 1,3-diphenylallyl cations, has been investigated by variable temperature 1H NMR spectroscopy. At low temperature, the three allylic protons give rise to an AMX system, and the two diastereotopic S-methyl groups resonate at different frequencies. At higher temperature, an AX2 system for the allylic protons and a single signal for the S-methyl groups are observed. The resulting exchange rate constant of (364 ± 2) s–1 at 25°C, which corresponds to the rate of the heterolytic cleavage of the C–S bond, was used to explore the range of validity of the linear free energy relationship log khet(25°C) = sf (Nf + Ef), which describes the rates of heterolytic cleavages by the electrofugality parameter Ef and the solvent-dependent nucleofuge-specific parameters Nf and sf. The observed rate constant corroborates a previous conclusion that two different sets of Nf and sf parameters may exist for the same nucleofuge. Knowledge of whether the reverse bond-forming reaction occurs under activation or under diffusion control is crucial for the choice of the appropriate set of nucleofugality parameters.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 0894-3230
• Sprache: Englisch