Environmentally-benign, non-toxic electrolytes with combinatorial design spaces are excellent candidates for green solvents, green leaching agents, and carbon capture sources. Here, we examine one particular green solvent, ethaline, a 2:1 molar ratio of ethylene glycol and choline chloride. Despite its touted green credentials, we find partial decomposition of ethaline into toxic chloromethane and dimethylaminoethanol at room temperature, limiting its sustainable advantage. We experimentally characterize these decomposition products and computationally develop a general, quantum chemically-accurate workflow to understand decomposition. We find that fluctuations of the hydrogen bonds bind chloride near reaction sites, initiating the reaction between choline cations and chloride anions. In summary, in the design of green solvents, we do not recommend the use of choline chloride due to its susceptibility to undergo decomposition in strongly hydrogen-bound mixtures.
Cite
@article{arxiv.2410.05498,
title = {Room-temperature decomposition of the ethaline deep eutectic solvent},
author = {Julia H. Yang and Amanda Whai Shin Ooi and Zachary A. H. Goodwin and Yu Xie and Jingxuan Ding and Stefano Falletta and Ah-Hyung Alissa Park and Boris Kozinsky},
journal= {arXiv preprint arXiv:2410.05498},
year = {2025}
}
Comments
Accepted at The Journal of Physical Chemistry Letters (Feb. 12, 2025)