Solute–Solvent Interactions of 2,2,6,6-Tetramethylpiperidinyloxyl and 5-Tert-Butylisophthalic Acid in Polyethylene Glycol as Observed by Measurements of Density, Viscosity, and Self-Diffusion Coefficient
Solute–Solvent Interactions of 2,2,6,6-Tetramethylpiperidinyloxyl and 5-Tert-Butylisophthalic Acid in Polyethylene Glycol as Observed by Measurements of Density, Viscosity, and Self-Diffusion Coefficient
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DOI：
10.1007/s10953-023-01265-4
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发表时间：
2023-03
影响因子：
1.2
通讯作者：
M. Hoffmann;Nathaniel P. Randall;Miray H. Apak;Nathaniel A. Paddock;T. Gutmann;G. Buntkowsky
中科院分区：
文献类型：
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作者：
M. Hoffmann;Nathaniel P. Randall;Miray H. Apak;Nathaniel A. Paddock;T. Gutmann;G. Buntkowsky
本研究旨在更好地了解聚乙二醇（PEG）作为溶剂，以促进其在化学合成中的应用。在298.15-358.15 K的温度范围内，研究了在PEG200（平均摩尔质量为200 g·mol−1）中加入2,2,6,6-四甲基胡椒酰氧基（TEMPO）和5-叔丁基邻苯二酸（5-TBIPA）两种溶质对溶液密度、粘度和自扩散系数的影响，以推断这些溶质如何与PEG200溶剂相互作用。水是聚乙二醇中最常见的杂质，它的影响也被监测到，发现几乎可以忽略不计。（5-TBIPA）的加入增加了溶液的密度和粘度。在所有实验条件下，5-TBIPA始终以PEG200的一半速率自扩散，这表明可能通过氢键相互作用产生强烈的吸引溶质-溶剂相互作用。相比之下，加入TEMPO会降低溶液密度和粘度，这表明与纯PEG200相比，TEMPO的溶质-溶剂相互作用导致分子间相互作用的整体减弱。对粘度和自扩散温度依赖关系的检查显示与阿伦尼乌斯方程有轻微的偏差。有趣的是，从粘度和自扩散数据中得到的活化能在数值上基本相同，这表明在这些PEG200溶液中，相同的动力学过程和相同的激活垒控制着平移运动和动量传递。图形抽象
This study is seeking a better understanding of polyethylene glycol (PEG) as a solvent to promote its use in chemical synthesis. The effect of adding two solutes of interest, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) and 5-tert-butylisophthalic acid (5-TBIPA) to PEG200 (average molar weight of 200 g·mol−1) on the solution density, viscosity, and self-diffusion coefficients is monitored in a temperature range of 298.15–358.15 K to deduce how these solutes interact with the PEG200 solvent. The effect of water, the most common impurity in PEGs, is also monitored and found to be nearly negligibly small. Addition of (5-TBIPA) increases solution density and viscosity. Combined with the observation that 5-TBIPA consistently self-diffuses at about half the rate as PEG200 at all investigated experimental conditions, this suggests strong attractive solute–solvent interactions likely through hydrogen bonding interactions. In contrast, addition of TEMPO causes lower solution densities and viscosities suggesting that the solute–solvent interactions of TEMPO lead to an overall weakening of the intermolecular interactions present compared to neat PEG200. Inspection of the viscosity and self-diffusion temperature dependence reveals slight deviations from the Arrhenius equation. Interestingly, the activation energies obtained from the viscosity and the self-diffusion data are essentially identical in values suggesting that the same dynamic processes and thus the same activation barriers govern translational motion and momentum transfer in these PEG200 solutions.Graphical Abstract