Determination of pK (a)and the corresponding structures of quinclorac using combined experimental and theoretical approaches

文献类型： 外文期刊

第一作者： Song, Dean

作者： Song, Dean;Sun, Huiqing;Kong, Fanyu;Song, Dean;Qiang, Zhimin;Zhang, Aiqian;Liu, Huijuan;Qu, Jiuhui;Jiang, Xiaohua

作者机构：

关键词： Quinclorac;pK(a);Spectrophotometric method;Quantitative structure property relationship method;DFT geometry optimization

期刊名称：JOURNAL OF MOLECULAR STRUCTURE （ 影响因子：3.196； 五年影响因子：2.618 ）

ISSN： 0022-2860

年卷期： 2018 年 1152 卷

页码：

收录情况： SCI

摘要： As an emerging environmental contaminant, the herbicide quinclorac has attracted much attention in recent years. However, a very fundamental issue, the acid dissociation of quinclorac has not yet to be studied in detail. Herein, the p/f (a) value and the corresponding structures of quinclorac were systematically investigated using combined experimental and theoretical approaches. The experimental p/C(a)of quinclorac was determined by the spectrophotometric method to be 2.65 at 25 degrees C with ionic strength of 0.05 M, and was corrected to be 2.56 at ionic strength of zero. The molecular structures of quinclorac were then located by employing the DFT calculation. The anionic quinclorac was directly located with the carboxylic group perpendicular to the aromatic ring, while neutral quinclorac was found to be the equivalent twin structures. The result was further confirmed by analyzing the UV/Vis and MS-MS2 spectra from both experimental and theoretical viewpoints. By employing the QSPR approach, the theoretical pK(a) of QCR was determined to be 2.50, which is excellent agreement with the experimental result obtained herein. The protonation of QCR at the carboxylic group instead of the quinoline structure was attributed to the weak electronegative property of nitrogen atom induced by the electron-withdrawing groups. It is anticipated that this work could not only help in gaining a deep insight into the acid dissociation of quinclorac but also offering the key information on its reaction and interaction with others. (c) 2017 Elsevier B.V. All rights reserved.

分类号：

  • 相关文献
作者其他论文 更多>>

微信小程序