Exploring Polar Organometallic Chemistry with Deep Eutectic Solvents in the Undergraduate Laboratory

Abstract

Polar organolithium reagents are central to modern synthetic chemistry but are rarely used in undergraduate laboratories because of the need for inert atmospheric techniques and cryogenic conditions. This study introduces a deep eutectic solvent (DES) composed of choline chloride and glycerol as an accessible reaction medium that enables the nucleophilic addition of n-butyllithium to an imine under ambient conditions and in air. Students prepare the DES, carry out the organolithium addition, and analyze the reaction outcome using FT-IR spectroscopy to confirm imine to amine conversion. Across seven cohorts, the experiment consistently afforded average student yields of approximately 70% and produced reproducible FT-IR spectra that clearly differentiate starting material and product. These results demonstrate that DES-mediated organolithium chemistry can be safely and effectively incorporated into undergraduate teaching laboratories, broadening student exposure to reactive organometallic reagents while reducing logistical and safety barriers.