Harnessing the acidity of HF/base reagents is of paramount importance to improve the efficiency and selectivity of fluorination reactions. Yet, no general method has been reported to evaluate their acidic properties, and experimental designs are still relying on a trial-and-error approach. We report a new method based on ¹⁹F NMR spectroscopy which allows highly sensitive measures and short-time analyses. Advantageously, the basic properties of the indicators can be determined upstream by DFT calculations, affording a simple yet robust semiempirical approach. In particular, the indicators used in this study were rationally designed to fit on the conceptually appealing and commonly used Hammett scale. This method has been applied to commercially available and recently developed HF/base reagents.

中文翻译：

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HF/碱试剂哈米特酸度的测定

利用 HF/碱试剂的酸性对于提高氟化反应的效率和选择性至关重要。然而，尚未报道评估其酸性特性的通用方法，并且实验设计仍然依赖于试错法。我们报告了一种基于¹⁹ F NMR 光谱的新方法，可实现高灵敏度测量和短时间分析。有利的是，指标的基本属性可以通过DFT计算在上游确定，从而提供简单而稳健的半经验方法。特别是，本研究中使用的指标经过合理设计，符合概念上有吸引力且常用的哈米特量表。该方法已应用于市售和最近开发的 HF/碱试剂。