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Published on: October 19, 2017
Synthesis and Structure of Protonated Propiolic Acid
Dirk Hollenwäger1, Simon Thamm1, Valentin Bockmair1
1Department of Chemistry, University of Munich (LMU), Munich 81377, Germany.
Abstract:
Propiolic acid was investigated in the superacidic system XF/SbF5 (X = H, D). The salts of the monoprotonated species of propiolic acid were characterized by vibrational and NMR spectroscopy as well as single-crystal analyses. The rotational conformers of the protonated species can be distinguished by NMR spectroscopy via the temperature-dependent rotational barrier. In the solid state, they can be detected by H/D exchange and packing effects due to different anions. The experimental results are discussed together with an IRC calculation of the rotational barrier. After acetic acid and formic acid, this is the third protonated carboxylic acid for which the energy differences between the conformers have been determined.
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