Green Solvents

In recent years, a large number of studies on the application of ionic liquids (ILs) and deep eutectic solvents (DESs) as alternative solvents for the extraction of various bioactive compounds such as alkaloids, antioxidants, phenolic compounds, saponins, anthraquinones and isoflavones, including some short chain carboxylic acids have been reported. ILs can be “created and/or designed” from a wide variety of cation and anion precursors for the purpose of obtaining improved properties and playing a specific role in any process. In particular, protic ILs have been considered promising solvents for sustainable and environmentally friendly chemistry due to their ease of synthesis, low cost, predisposition to establish strong hydrogen bonds, high yield, low toxicity, reduced vapor pressure, high ability to solubilize organic, inorganic, biochemical, petrochemical, polymers compounds, easily recycled and potentially biodegradable in water. Other environmentally friendly (“green”), non-flammable, non-toxic and biodegradable solvents with high potential in industrial applications are Deep Eutectic Solvents (DESs). The DESs are mixtures of two or more compounds (one of which is ionic) which, to a well-defined composition, exhibit a low melting point resulting in a strong deviation from the ideality of the liquid mixture as a consequence of acid-base interaction (hydrogen bonds). Therefore, ILs and DESs can be great candidates for use as solvents in extractive processes.