Free jet rotational spectrum of the most stable conformer of 1-(2-fluorophenyl)-1-ethanol

Influence of Fluorination on the Conformational Properties and Hydrogen‐Bond Acidity of Benzyl Alcohol Derivatives

“…For the o‐ monofluorinated secondary benzyl alcohol 7 b , the planar conformation does not feature in the low‐energy conformational landscape. In its main low‐energy structures, the CHOHCH 3 bond is perpendicular to the plane of the phenyl ring, similar to the major ethyl benzene conformation and as found previously in the gas phase by MW spectroscopy 25. In addition, approximately 10 % of the conformers have both the methyl and the hydroxyl groups in the gauche position.…”

“…[ 23 ] The main suggested conformers of benzyl alcohol derivatives, defined by the ϕ (C ortho C ipso C α O) and χ (C ipso C α OH) dihedral angles, are the gauche _ gauche ( g _ g , also sometimes referred to as gauche _ cis ), gauche _ trans ( g _ t ), planar ( pl ) and perpendicular ( perp ) conformers (Figure 4 a,b and the Supporting Information for further details). In monofluorinated benzyl alcohols, the introduction of a methyl group at the C α carbon was found to have a significant influence on the preferred conformation compared with o -fluoro benzyl alcohol, preferentially showing an OH⋅⋅⋅F IMHB,[ 24 ] to 2-fluoro-α-methylbenzyl alcohol,[ 25 ] mainly stabilised with an OH⋅⋅⋅π interaction. Theoretical calculations in the gas phase generally attribute the absolute minimum to the gauche _ gauche conformation.…”

“…In its main low-energy structures, the CHOH–CH 3 bond is perpendicular to the plane of the phenyl ring, similar to the major ethyl benzene conformation and as found previously in the gas phase by MW spectroscopy. [ 25 ] In addition, approximately 10 % of the conformers have both the methyl and the hydroxyl groups in the gauche position. It is interesting to note that, apart from the chelated conformer, there is little preference for fluorine position: the proximal and distal populations are not significantly different.…”