Lõkov Märt, Kesküla Carmen, Tshepelevitsh Sofja, Pikma Marta-Lisette, Saame Jaan, Trubitsõn Dmitri, Kanger Tõnis, Leito Ivo
Institute of Chemistry, University of Tartu, Tartu 50411, Estonia.
Department of Chemistry & Biotechnology, Tallinn University of Technology, 12618 Tallinn, Estonia.
ACS Org Inorg Au. 2025 Mar 13;5(2):144-155. doi: 10.1021/acsorginorgau.4c00095. eCollection 2025 Apr 2.
Nitrogen heterocycles and aromatic amines are well-known and widely used compounds that are usually not seen as acids, although in organic solvents like acetonitrile (MeCN) or dimethyl sulfoxide (DMSO) their acidic properties can be observed. In this work, the acidities (p values) of 37 such weak NH acids were determined in acetonitrile and presented together with computational gas-phase acidities and literature p values in DMSO. In the course of the work the weakest acids range (from p 29 upward) of the MeCN acidity scale has been revised and expanded to around 33.5 by adding 31 compounds in that specific region and the span of experimental p values in MeCN is now more than 30 orders of magnitude. The relations between the structure and acidity of a selection of the studied compounds have been investigated in MeCN and DMSO. The measured p values in MeCN and the gathered p values in DMSO were used for a correlation analysis between the two solvents and for assessing the quality of p conversion equations. A number of p values have been predicted in MeCN from p values in DMSO via the correlation analysis and p conversion equations.
氮杂环和芳香胺是众所周知且广泛使用的化合物，通常不被视为酸，尽管在乙腈（MeCN）或二甲基亚砜（DMSO）等有机溶剂中可以观察到它们的酸性。在这项工作中，测定了37种此类弱NH酸在乙腈中的酸度（p值），并与计算得到的气相酸度以及DMSO中的文献p值一同呈现。在工作过程中，通过在该特定区域添加31种化合物，乙腈酸度标度中最弱的酸范围（从p 29向上）已被修正并扩展至约33.5，且乙腈中实验p值的跨度现在超过30个数量级。在乙腈和DMSO中研究了所选研究化合物的结构与酸度之间的关系。将在乙腈中测得的p值和在DMSO中收集的p值用于两种溶剂之间的相关性分析以及评估p转换方程的质量。通过相关性分析和p转换方程，从DMSO中的p值预测了乙腈中的一些p值。
