Sporzyński Andrzej, Adamczyk-Woźniak Agnieszka, Zarzeczańska Dorota, Gozdalik Jan T, Ramotowska Paulina, Abramczyk Wiktoria
Faculty of Agriculture and Forestry, University of Warmia and Mazury, Oczapowskiego 2, 10-719 Olsztyn, Poland.
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Molecules. 2024 Jun 6;29(11):2713. doi: 10.3390/molecules29112713.
The wide use of boronic compounds, especially boronic acids and benzoxaboroles, in virtually all fields of chemistry is related to their specific properties. The most important of them are the ability to form cyclic esters with diols and the complexation of anions. In both cases, the equilibrium of the reaction depends mainly on the acidity of the compounds, although other factors must also be taken into account. Quantification of the acidity (p value) is a fundamental factor considered when designing new compounds of practical importance. The aim of the current work was to collect available values of the acidity constants of monosubstituted phenylboronic acids, critically evaluate these data, and supplement the database with data for missing compounds. Measurements were made using various methods, as a result of which a fast and reliable method for determining the p of boronic compounds was selected. For an extensive database of monosubstituted phenylboronic acids, their correlation with their Brønsted analogues-namely carboxylic acids-was examined. Compounds with ortho substituents do not show any correlation, which is due to the different natures of both types of acids. Nonetheless, both meta- and para-substituted compounds show excellent correlation. From a practical point of view, acidity constants are best determined from the Hammett equation. Computational approaches for determining acidity constants were also analyzed. In general, the reported calculated values are not compatible with experimental ones, providing comparable results only for selected groups of compounds.
硼酸化合物，尤其是硼酸和苯并氧杂硼唑，在化学的几乎所有领域的广泛应用都与其特殊性质有关。其中最重要的是它们与二醇形成环状酯的能力以及与阴离子的络合作用。在这两种情况下，反应的平衡主要取决于化合物的酸度，不过其他因素也必须加以考虑。酸度（p值）的量化是设计具有实际重要性的新化合物时要考虑的一个基本因素。当前工作的目的是收集单取代苯硼酸的酸度常数的可用值，严格评估这些数据，并为缺失化合物的数据补充数据库。使用了各种方法进行测量，结果选择了一种快速可靠的测定硼酸化合物p值的方法。对于单取代苯硼酸的广泛数据库，研究了它们与布朗斯特类似物——即羧酸——之间的相关性。具有邻位取代基的化合物没有显示出任何相关性，这是由于这两种酸的性质不同。尽管如此，间位和对位取代的化合物都显示出极好的相关性。从实际角度来看，酸度常数最好由哈米特方程确定。还分析了测定酸度常数的计算方法。一般来说，所报道的计算值与实验值不相符，仅对选定的化合物组提供可比的结果。
