Laboratoire CEISAM, UMR CNRS 6230, Faculté des Sciences et des Techniques, Université de Nantes, 2, rue de la Houssinière, BP 92208, 44322 Nantes, Cedex 3, France.
J Org Chem. 2010 Jun 18;75(12):4105-23. doi: 10.1021/jo100461z.
The thermodynamics of the O-H...B hydrogen bond (HB) has been determined in CCl(4) by FTIR spectrometry for a wide variety of carbon pi bases, oxygen bases, and miscellaneous first- to fourth-row bases, using 4-fluorophenol as a reference hydrogen-bond donor (HBD). After inclusion of previously studied nitrogen, sulfur, and halogen bases, this 4-fluorophenol affinity scale contains 314 varied organic bases and ranges over 40 kJ mol(-1). The 4-fluorophenol affinity scale in CCl(4) is shown to be applicable to most HBDs in most media, provided a small family dependence is taken into account. The HB affinity orders are quantitatively established according to the atomic acceptor site or to its bearing functional group. A comprehensive survey of the influence of substituents on these affinity orders is then achieved, considering electronic and steric effects, as well as effects of vinylogy or iminology. Iminology is found to be more efficient than vinylogy for transmitting resonance effects. Steric effects are shown to be less important in HB affinity than in HB basicity since they mainly act on the HB entropy. The spatial proximity of two acceptor sites can favor complexation through three-center hydrogen bonds, leading to superhydrogen-bond bases on the affinity scale.
通过使用 4-氟苯酚作为参考氢键供体（HBD），在 CCl4 中通过傅里叶变换红外光谱法确定了 O-H...B 氢键（HB）的热力学性质，研究了各种各样的碳π碱基、氧碱基和各种第一至第四排碱基。在包含先前研究的氮、硫和卤素碱基后，这个 4-氟苯酚亲和标度包含了 314 种不同的有机碱基，范围超过 40 kJ mol(-1)。在 CCl4 中，4-氟苯酚亲和标度被证明适用于大多数 HBD 在大多数介质中，只要考虑到小的家族依赖性。根据原子受体位点或其承载的官能团，定量建立了 HB 亲和顺序。然后，考虑电子和空间效应以及乙烯基或亚氨基的影响，全面研究了取代基对这些亲和顺序的影响。发现亚氨基比乙烯基更有效地传递共振效应。与 HB 碱性相比，HB 亲合性中的空间效应不太重要，因为它们主要作用于 HB 熵。两个受体位点的空间接近可以通过三中心氢键促进络合，从而导致在亲和标度上的超氢键碱基。
