(Bio)Catalytic Continuous Flow Processes in scCO2 and/or ILs: Towards Sustainable (Bio)Catalytic Synthetic Platforms

Abstract

This review highlights the tool box for the development of continuous green/sustainable processes aimed at the synthesis of fine chemicals. By combining either chemical and/or biological catalysts with biphasic systems based on neoteric solvents, e.g. ionic liquids (ILs) and supercritical carbon dioxide (scCO2), interesting alternatives to organic solvents for designing continuous clean (bio)transformations methods are growing that directly provide pure products. The classical advantages of scCO2 -its ability to extract, dissolve and transport chemicals-are complemented by the high catalytic efficiency of enzymes in ILs. Enzyme behavior in scCO2 and ILs, as well as the phase behavior of ILs/scCO2, are key parameters for carrying out integral green bioprocesses in continuous operation. The preparation, main characteristics and advantages of monolithic microreactors and miniflow reactors for the synthesis of fine chemicals by continuous flow (bio)catalytic processes are underlined. Examples where the use of continuous flow techniques for multi-step synthesis enables multiple reaction steps to be combined into a single continuous operation are provided.

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

“…This approach leads to ideally perfect control of the size and the shape of the environment inside the cavities or on the surface of the material, enhancing the control of the chemophysical properties of the resulting materials. 314,315 There are literally hundreds of reports and dozens of specialized reviews dealing with the SILP catalyst approach, and various definitions have been used throughout the literature. The acronym SILP is used throughout this manuscript, but it should be pointed out that depending upon the nature of the catalyst and the IL, the catalytic system has been described as 177,316 (i) supported IL catalysis/catalysts (SILC/SILCA), 317 (ii) supported IL NPs (SILNPs), 318 (iii) supported IL phase (SILP), 319 (iv) supported IL phase catalyst (SILPC), 320 (v) IL crystalline-SILP (ILC-SILP), 321,322 (vi) structured SILP (SSILP), 323 (vii) supported ionic-like phase (SILLP), 324 (viii) polymer supported IL (PSIL), 325 (ix) supported IL membrane (SILM), 289,326 (x) sponge-like ILs (SLILs), 285 (xi) IL Pickering emulsions (ILPEs), 327 or (xii) ILbased aqueous biphasic systems (IL-based ABSs).…”

“…The topology and porosity of the support can be tailored by varying the synthetic methodology and the connectivity, size, and geometry of the building blocks by a bottom-up approach. This approach leads to ideally perfect control of the size and the shape of the environment inside the cavities or on the surface of the material, enhancing the control of the chemophysical properties of the resulting materials. , …”