Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States.
J Org Chem. 2021 May 7;86(9):6031-6043. doi: 10.1021/acs.joc.0c02876. Epub 2021 Apr 21.
The hydrogen-bond-accepting abilities for more than 100 organic molecules are quantified using F and P NMR spectroscopy with pentafluorobenzoic acid (PFBA) and phenylphosphinic acid (PPA) as commercially available, inexpensive probes. Analysis of pyridines and anilines with a variety of electronic modifications demonstrates that changes in NMR shifts can predict the secondary effects that contribute to H-bond-accepting ability, establishing the ability of PFBA and PPA binding to predict electronic trends. The H-bond-accepting abilities of various metal-chelating ligands and organocatalysts are also quantified. The measured Δδ(P) and Δδ(F) values correlate strongly with Hammett parameters, p of the protonated HBA, and proton-transfer basicity (p).
使用五氟苯甲酸 (PFBA) 和苯膦酸 (PPA) 作为商业上可获得的廉价探针，通过 F 和 P NMR 光谱对 100 多种有机分子的氢键接受能力进行定量。对具有各种电子修饰的吡啶和苯胺的分析表明，NMR 位移的变化可以预测对氢键接受能力有贡献的次级效应，从而确立了 PFBA 和 PPA 结合预测电子趋势的能力。还对各种金属螯合配体和有机催化剂的氢键接受能力进行了定量。测量的 Δδ(P) 和 Δδ(F) 值与哈米特参数、质子化 HBA 的 p 值和质子转移碱性 (p) 密切相关。
