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A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
The C(2v) structure of enolic acetylacetone
Walther Caminati1, Jens-Uwe Grabow
1Dipartimento di Chimica, G. Ciamician dell'Università, Via Selmi 2, I-40126 Bologna, Italy. walther.caminati@unibo.it
Journal of the American Chemical Society
|January 19, 2006
Summary
The enolic form of Acetylacetone (AcAc) has C(2v) symmetry, not C(s) as previously thought. This molecule is highly dynamic due to a low barrier for internal methyl group rotation.
Area of Science:
- Molecular spectroscopy
- Quantum chemistry
- Chemical physics
Background:
- The enolic form of Acetylacetone (AcAc) has been debated regarding its symmetry, with C(s) and C(2v) structures proposed.
- Previous studies suggested a double-minimum potential and low proton transfer barrier for the C(s) form.
- Conflicting theoretical and experimental results exist in the literature.
Purpose of the Study:
- To definitively determine the symmetry of the enolic form of Acetylacetone.
- To investigate the internal dynamics of Acetylacetone using high-resolution rotational spectroscopy.
Main Methods:
- High-resolution rotational spectroscopy was employed.
- Measurements were performed on enolic Acetylacetone and three isotopologues.
Main Results:
- The experimental results revealed a C(2v) symmetry for enolic Acetylacetone.
- A very low barrier to internal rotation of the methyl groups was identified.
- This indicates significant internal dynamics within the molecule.
Conclusions:
- The enolic form of Acetylacetone possesses C(2v) symmetry.
- Acetylacetone is an internally dynamic molecule due to facile methyl group rotation.
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