Abstract
A deep eutectic solvent（DES）is a liquid composed of two or more solids or liquids that form hydrogen bonds. DESs are expected to replace organic solvents and have been widely studied for the extraction and synthesis of various substances. In addition, DESs consisting of organic acids and sugars and three-component DESs have been reported in recent years. The authors have prepared DESs that can easily dissolve active pharmaceutical ingredients（APIs）and demonstrated their potential use as solvents for APIs. In particular, the solubility of tadalafil, a poorly water-soluble API, was confirmed to be 24800 times higher than that of water. In addition, a slurry of carbamazepine dispersed in DES containing malonic acid was prepared, and carbamazepine was successfully converted to a co-crystal with malonic acid by bead milling. In this paper, we will discuss the usefulness of DES in alternative solvents and crystallization.
