State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin 300071, China.
J Org Chem. 2017 Sep 15;82(18):9675-9681. doi: 10.1021/acs.joc.7b01755. Epub 2017 Aug 30.
An acidity scale of triazolium-based N-heterocyclic carbene precursors was established by measuring 25 compounds' (10a-15b) equilibrium acidities in dimethyl sulfoxide (DMSO) solution using overlapping indicator method. The pK values ranged from 12.08 to 15.5, responding not only to the N-aryl motif, but also to the core structure. Excellent correlation was observed between the pK values and the Hammett substituent constants (σ).
通过使用重叠指示剂法测量 25 种化合物（10a-15b）在二甲基亚砜（DMSO）溶液中的平衡酸度，建立了基于三唑鎓的 N-杂环卡宾前体的酸度标度。pK 值范围为 12.08 至 15.5，不仅响应于 N-芳基基序，而且响应于核心结构。观察到 pK 值与哈米特取代常数（σ）之间存在极好的相关性。
