Disentangling the Conformational Space and Structural Preferences of Tetrahydrofurfuryl Alcohol Using Rotational Spectroscopy and Computational Chemistry.
Chemphyschem
; 25(12): e202400298, 2024 Jun 17.
Article
em En
| MEDLINE
| ID: mdl-38637291
ABSTRACT
The influence of the hydroxymethyl (CH2OH) group on the tetrahydrofuran (THF) ring structure was investigated by disentangling the gas phase conformational landscape of the sugar analogue tetrahydrofurfuryl alcohol (THFA). By combining rotational spectroscopy (6-20â
GHz) and quantum chemical calculations, transitions corresponding to two stable conformers of THFA and their 13C isotopologues were observed and assigned in the rotational spectrum. The positions of the C atoms were precisely determined to unambiguously distinguish between nearly isoenergetic pairs of conformers that differ in their ring configurations envelope (E) versus twist (T). The rotational spectrum confirms that the E ring geometry is favoured when the CH2OH fragment lies gauche (-) to the THF backbone (OCCO ~-60°) whereas the T form is more stable for the gauche (+) alignment of the substituent (OCCO ~+60°). The observed spectral intensities suggest that conformational relaxation of the THF geometry (EâT) to the more stable form readily occurs within the pairs of g- and g+ conformers which is consistent with the low barriers (1.5-1.7â
kJ mol-1) for conversion determined via transition state calculations. Insights into the intramolecular hydrogen bonding and other weak interactions stabilizing the lowest energy structures of THFA were derived and rationalized using non-covalent interaction analyses.
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MEDLINE
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En
Ano de publicação:
2024
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Article