Acidity scales of deep eutectic solvents based on IR and NMR

Abstract

Acidic deep eutectic solvents (ADESs) have been utilized in various applications. Clearly, it is crucial to obtain acidity information that could reveal the relationship with performance. However, appropriate methods of...

Acidity Scale in a Choline Chloride- and Ethylene Glycol-Based Deep Eutectic Solvent and Its Implication on Carbon Dioxide Absorption

“…Systematic study of equilibrium acidities (p K a , the negative logarithm of the acid dissociation constant K a ) in solution has been proven to be a convenient and effective approach for detecting subtle solvation behaviors of solvents. In this regard, previously, a large number of acidity scales for different Brönsted acids in various molecular and ionic solvents have been established. − Through the acidity comparisons and correlations between solvents, several distinct solvation behaviors between molecular solvents and ionic media thus have been explicitly revealed. , In the past few years, although there have been several acidity investigations in a number of commonly seen DESs, most of these reports were focused on the relative acidities of DESs themselves in molecular solvents. − There is practically no investigation on the acidities for a relatively wide range of organic acids with various structures and electronic properties in neat DES systems. It is worth noting that Abbott and co-workers first reported acidities in several choline-based DESs; however, their work was mainly focused on a series of carboxylic acids (COO–H acids), with no report on the acidity determination of other types of organic compounds, such as C–H, O–H, and N–H acids.…”

Biomass-Based Acidic Deep Eutectic Solvents for Efficient Dissolution of Lignin: Towards Performance and Mechanism Elucidation

“…In comparison, the DESs using HBDs with the moderate pKa value showed satisfactory ability to dissolve AL and EHL. Besides pKa, the acidity of the DESs could be evaluated by the 31 P NMR chemical shift (δP) of trimethylphosphine oxide (TMPO) dissolved in the corresponding DES 46,47 , and the DES resulting in larger δP value has stronger acidity. Thus, the δP values of several DESs were determined by 31 P NMR, and the results were provided in Fig.…”

Quantification of alkalinity of deep eutectic solvents based on (H−) and NMR

“…[14][15][16][17] At present, researchers have conducted in-depth exploration of the properties of acidic DESs with the assistance of theoretical methods and experimental techniques. 18,19 However, it is worth noting that as the research continues to deepen, alkaline DESs are playing an increasingly important role in many fields. [20][21][22] The performance and applications of alkaline DESs have not been extensively studied compared to acidic DESs, which are widely used.…”