Whether hydroxyl hydrogen is directed towards a Lewis base substituent in an alkyl chain due to intramolecular hydrogen bonds or to avoid repulsion between the hydroxyl oxygen and the substituent is a debatable topic and difficult to probe. This is still more challenging when fluorine is the Lewis base substituent. This work reports a theoretical approach capable of dissecting the contributions from hydrogen bond and repulsion, allowing to decide which interaction dominates the orientation of the hydroxyl group in a high-energy tautomer of 3-fluoropiperidin-2-one. A comparison between the potential energy curves for the hydroxyl rotation in the axial and equatorial conformers revealed that repulsion between fluorine and oxygen contributes by ca. 1.2 kcal mol⁻¹ to destabilize the cis isomer, while intramolecular hydrogen bond between fluorine and the hydroxyl group amounts by ca. 0.9 kcal mol⁻¹ favoring the trans isomer. These are not the major effects governing the conformational equilibrium of the studied compound, which is rather dictated by N⋯O steric repulsion, but the obtained outcomes can be valuable to understand the role of F⋯H(O) hydrogen bonds in conformational analysis and, ultimately, in the design of performance fluorinated aliphatic alcohols.

由于分子内的氢键，羟基氢是否直接导向烷基链中的路易斯碱取代基，或避免羟基氧与取代基之间的排斥是一个有争议的话题，并且难以探究。当氟为路易斯碱取代基时，这仍然更具挑战性。这项工作报告了一种理论方法，该方法能够剖析氢键和斥力的作用，从而可以确定在高能3-氟哌啶-2-酮互变异构体中，哪种相互作用主导着羟基的取向。轴向和赤道构象异构体中羟基旋转的势能曲线之间的比较表明，氟和氧之间的排斥力约为ca。1.2 kcal mol ^-1使溶液不稳定顺式异构体，而氟和羟基之间的分子内氢键的量约为。0.9kcal mol ^-1有利于反式异构体。这些不是控制所研究化合物的构象平衡的主要作用，而是由N⋯O空间排斥决定，但是获得的结果对于理解F⋯H（O）氢键在构象分析和分析中的作用可能是有价值的。最终，是设计高性能的氟化脂族醇。