Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Green Technologies for the Production of Modified Lipids

In recent years, the use of green solvents in enzyme catalysis of lipophilic compounds is achieving increasing interest from different perspectives. Conducting reactions under supercritical fluids, ionic liquids, deep eutectic solvents, and other green solvents affords opportunities to overcome problems associated with the lack of solubility of lipids in conventional solvents and the poor miscibility of substrates. Research on the biocatalytic production of modified lipids in the framework of green chemistry is conducted to improve the efficiency of obtaining the desired products as well as the selectivity, stability, and activity of the enzymatic systems. This overview describes the fundamentals and characteristics of several types of green solvents, the main variables involved in enzymatic processes, and examples and applications in the field of lipid modification.

Syntheses of high molecular weight hydroxy functional copolymers by green and selective polycondensation methods

Synthesizing hydroxy-functional linear copolymers with high molecular weights (M_n) and low branching degree (Den%) remains challenging, although there has been much headway in the area of functional copolymers. Here, we studied the effect of polymerization methods (one-step or two-step) and solvents (organic solvent: diphenyl ether or ionic liquids: [C_nmim]TF₂N/BF₄/PF₆, n = 2, 4, 6, 8, or 10) on M_n and Den% of copolymers P(OA–GA) (1,8-octanediol adipate (O-A)/glycerol adipate (G-A)). The M_n of P(OA–GA) reached up to 53 937 g mol⁻¹ in two-step in diphenyl ether, and the Den% of glycerol can be controlled within 30%. The physical properties of these copolymers were investigated by contact angles, differential scanning calorimetry (DSC), and in vitro biodegradation. With increasing glycerol content in the polyesters, both hydrophilic properties and degradation properties increased. This system not only facilitates the synthesis of functional polyesters with high molecular weight and low branching, but also expands the possibility of using bio-based monomers to synthesize functional polymers.

High molecular weight hydroxy functional copolymers have been synthesized by two-step polycondensation.