Insights into DES Stability and Reactivity with Carboxylic Acids: A Computational Approach

The study examined the interactions between a deep eutectic solvent (DES) containing choline chloride (ChCl) along with ethylene glycol (EG) in a molar ratio of 1:3, and three carboxylic acids: acetic acid, propanoic acid and butanoic acid. The structural stability, electrical characteristics and dynamic behavior of these DES-carboxylic acid systems were investigated utilizing techniques like density functional theory (DFT), natural bond orbital (NBO) analysis and molecular dynamics (MD) simulations. The results showed that the addition of carboxylic acids in the DES framework had a substantial impact on the distribution of electrons and the interactions between molecules in the system. More specifically, the presence of longer alkyl chains in the acids caused a more significant disturbance in the hydrogen- bond network of the DES. This was observed through alterations in the electron localization function (ELF) and noncovalent interaction (NCI) investigations. The results yielded useful insights into the design and implementation of DESs, including improving their stability and reactivity through targeted acid interactions.