Sturlaugson, Adam

• Ph.D., Physical Chemistry, Stanford University, Stanford, CA 

• B.S., Chemistry & Biology, University of Sioux Falls, SD

Title: Chiral Deep Eutectic Solvents for Chiral Purification

Many biomolecules and pharmaceuticals are chiral ("handed"). A chiral molecule's biological function often depends on whether it is the "left-handed" (S) or "right-handed" (R) version, so separating R from S is a crucial step in drug synthesis. Traditional purification methods (extraction, chromatography, etc.) are relatively easy for non-chiral compounds but are much more difficult for mixtures of R. and S compounds. This is because the physical properties upon which these separation methods rely-such as solubility or polarity-are identical for the R and S versions of this molecule. The purification methods that do exist are tedious (classic diastereomeric cystallization) or expensive (chiral chromatography), or both.

Dr. Sturlaugson's lab is developing chiral deep eutectic solvents (DESs) as a potential solution to this long-standing R/S purification problem. A DES is a mixture of two (typically) solid substances that melts at a substantially lower temperature than the two pure solids. This dramatic drop occurs because of strong hydrogen bonding interactions between the two components, leading to the nonideal behavior and a significant melting point drop, often to below room temperature. The number of possible DESs is nearly endless, due to the many component pairing and mixture. When one or both of the DES compounds is a chiral molecule, the resulting solvent is also critical and displays unique solubilities for R and S solutes. This enables the DES to separate R/S mixtures by simple methods such as straight recrystallization or extraction-unlike conventional, non-chiral solvents.

Because many naturally occurring, chiral compounds can be used as the components of DESs (tartaric acid, menthol, lactic acid, amino acids, etc.), the preparation of chiral deep eutectics is convenient, inexpensive, eco-friendly, and non-toxic. However, their application as direct R/S separation solvents has not been extensively studied and appears to be reported only in a handful of theoretical and experimental papers since 2019.

The objective of the Sturlaugson lab over the summer of 2027 is to develop and characterize chiral deep eutectic solvents for use as R/S purification solvents. This will be pursued by creating chiral DESs from readily available, naturally-sourced, chiral components. Promising DESs will then be characterized by melting point, density, viscosity, and their efficiency in separating a mixture of R and S ibuprofen.

Ideal deep eutectic solvents from this project should be composed of inexpensive, naturally-sourced, non-toxic and eco-friendly chiral components; should have amenably low melting points and viscosities; and should demonstrate efficient purification of an R/S mixture. If found, such a DES could demonstrate a new, inexpensive, and efficient way to purify previously difficult-to-separate R/S mixtures of bioactive compounds, including chiral pharmaceuticals and biomolecules.