The one-pot four-component eco-friendly synthesis of spirooxindoles in deep eutectic solvent

Deep Eutectic Solvents Formed by Glycerol and Xylitol, Fructose and Sorbitol: Effect of the Different Sugars in Their Physicochemical Properties

The search for new eutectic solvents for different applications (extraction, drug formulation, chemical reactions, etc.) is booming thanks to their high solubility capacity and low toxicity. However, it is necessary to carry out a comprehensive physicochemical characterization of these mixtures to understand the molecular behavior at different experimental conditions. In this study, three deep eutectic solvents (DESs) formed by glycerol and xylitol, fructose and sorbitol and water in the molar ratio 1:2:3 were prepared and several physicochemical properties (refractive index, density, surface tension, viscosity, speed of sound, isobaric heat capacity and isentropic compressibility) were measured and analyzed in the 278.15-338.15 K temperature range. The results indicate a linear dependence with temperature for the following properties: surface tension, refractive index, density and isobaric molar heat capacity while viscosity values have been fitted to the Vogel-Fulcher-Tammann equation.

Applications of Choline Chlorine based Deep Eutectic Solvents as Sustainable Media and catalyst in the synthesis of Heterocyclic Scaffolds

Abstract:

Deep eutectic solvents (DESs), also referred to as low transition temperature mixtures (LTTMs), have emerged as sustainable and cheap alternatives to conventional organic solvents in organic synthesis. This is attributed to their exceptional characteristics viz. easy preparation with readily available cheap materials, water compatibility, non-flammability, non-toxicity, biocompatibility, biodegradability, etc. All these properties label them as versatile and cost-effective green solvents. The first reported DES, choline chloride urea mixture has appeared as an innocuous solvent and catalyst in many organic transformations. This prospective DES combination has been applied extensively to the synthesis of a wide range of heterocyclic compounds including quinolones, spirooxindoles, etc. The conditions employed are relatively mild and do not require additional acid catalysts or organic solvents. This eco-friendly blend for the synthesis of heterocycles reports excellent yields of products with shorter reaction times and a simple workup procedure. Evaluating these merits, this review focuses on the recent literature published on the use of choline chlorine-based DESs in the synthesis of a few important heterocyclic compounds.