Fine-tuning the Basicity of Deep Eutectic Solvents by Substituting Guanidine for Urea in Reline

ACS Omega. 2023 Apr 12;8(16):14694-14698. doi: 10.1021/acsomega.3c00706. eCollection 2023 Apr 25.


The physicochemical properties of deep eutectic solvents (DESs) depend on the combination of hydrogen bond acceptors and hydrogen bond donors used. The basicity of a DES significantly influences its performance in CO2 chemical absorption, biomass and protein dissolution, and catalytic reactions. To the best of our knowledge, a strategy for fine-tuning the basicity of DESs has not yet been reported. Therefore, in this study, we substituted the base urea (Ur) in reline, which is a 1:2 mixture of choline chloride (ChCl) and Ur, with the superbase guanidine (Gu) to fine-tune its basicity. Binary (2Gu-ChCl) and ternary (Gu-Ur-ChCl) DESs were prepared, and their CO2 absorption capacities were investigated at 313.2 K. The equimolar mixture Gu-Ur-ChCl absorbed CO2 gas up to the molar ratio [CO2]/[ChCl] ≈ 1.0. Therefore, the basicity of ChCl-based DES can be continuously varied by substituting more molecules of Ur with Gu. Our strategy of combining functional and non-functional molecules with similar structures to vary the basicity of DESs has potentially wide applications that utilize DESs in the future.

PMID:37125108 | PMC:PMC10134474 | DOI:10.1021/acsomega.3c00706


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