Ionic Liquid Droplet Microreactor for Catalysis Reactions Not at Equilibrium

Abstract

We develop a novel strategy to more effectively and controllably process continuous enzymatic or homogeneous catalysis reactions based on nonaqueous Pickering emulsions. A key element of this strategy is "bottom-up" construction of a macroscale continuous flow reaction system through packing catalyst-containing micron-sized ionic liquid (IL) droplet in oil in a column reactor. Due to the continuous influx of reactants into the droplet microreactors and the continuous release of products from the droplet microreactors, catalysis reactions in such a system can take place without limitations arising from establishment of the reaction equilibrium and catalyst separation, inherent in conventional batch reactions. As proof of the concept, enzymatic enantioselective trans-esterification and CuI-catalyzed cycloaddition reactions using this IL droplet-based flow system both exhibit 8 to 25-fold enhancement in catalysis efficiency compared to their batch counterparts, and a durability of at least 4000 h for the enantioselective trans-esterification of 1-phenylethyl alcohol, otherwise unattainable in their batch counterparts. We further establish a theoretical model for such a catalysis system working under nonequilibrium conditions, which not only supports the experimental results but also helps to predict reaction progress at a microscale level. Being operationally simple, efficient, and adaptive, this strategy provides an unprecedented platform for practical applications of enzymes and homogeneous catalysts even at a controllable level.

Submicron Inverse Pickering Emulsions for Highly Efficient and Recyclable Enzymatic Catalysis

“…Pickering emulsions, a type of emulsion that are stabilized by colloidal particles, have attracted tremendous interest for biphasic enzyme catalysis . Compared to conventional surfactant‐stabilized emulsions, Pickering emulsions offer many unique advantages, such as enhanced enzyme stability, simplified product separation, and facile enzyme recycling.…”

“…[8] Pickering emulsions, at ype of emulsion that are stabilized by colloidal particles, have attracted tremendousi nterest for biphasic enzymec atalysis. [9][10][11][12][13][14][15][16][17] Compared to conventional surfactant-stabilized emulsions, Pickering emulsions offer many unique advantages,s uch as enhanced enzyme stability, simplified product separation, and facile enzyme recycling. Pioneering work on the immobilization of enzymesb yu sing Pickering emulsions was accomplished by the groups of Wang and van Hest, who used hydrophobic SiO 2 nanoparticles and polymersomes, respectively,t oe mulsify aqueous solutionso fe nzymes in organic medium.…”

Phosphonium acidic ionic liquid: an efficient and recyclable homogeneous catalyst for the synthesis of 2-arylbenzoxazoles, 2-arylbenzimidazoles, and 2-arylbenzothiazoles

“…[25][26][27][28][29] They have been widely used as catalysts for a large number of organic transformations. [30][31][32][33][34][35][36][37][38][39] However, their application as catalysts for the synthesis of 2-arylbenzoxazole, 2-arylbenzimidazoles, and 2-arylbenzothiazoles via the condensation of aldehydes with o-aminophenols, o-phenylenediamine, and o-aminothiophenols, respectively, has not been known in the literature. In the continuation of our study in ionic liquids application, we reported herein the use of phosphonium acidic ionic liquid as a green and efficient catalyst for the synthesis of the above mentioned arylated heterocycles.…”

Tandem Catalysis with Antagonistic Catalysts Compartmentalized in the Dispersed and Continuous Phases of a Pickering Emulsion

“…Furthermore, noninterference cannot always be avoided and catalystnon-compatibility in fact offers another main challenge for efficient tandem catalysis, for example when combining antagonistic catalysts such as an acid andabase. [18][19][20][21][22] For example, Resasco and coworkers reported on phase-selective catalysis using carbon nanotube-silica nanohybrids stabilized PEs in catalytic hydrogenationr eactions [23,24] andt he catalytic upgrading of biofuels by using hydrophobic zeolites acting as PE stabilizers. Various approaches have been taken towards the design of bifunctional acid-base catalysts, often relying on the spatial separation of the reactive entities on polymeric or oxidic support materials, [5,6] for example, in the form of yolk-shellm aterials, [7] metal-organic frameworks (MOFs), [8][9][10][11] shell cross-linked micelles, [12,13] or star polymers.…”

“…[18][19][20][21][22] For example, Resasco and coworkers reported on phase-selective catalysis using carbon nanotube-silica nanohybrids stabilized PEs in catalytic hydrogenationr eactions [23,24] andt he catalytic upgrading of biofuels by using hydrophobic zeolites acting as PE stabilizers. [18][19][20][21][22] For example, Resasco and coworkers reported on phase-selective catalysis using carbon nanotube-silica nanohybrids stabilized PEs in catalytic hydrogenationr eactions [23,24] andt he catalytic upgrading of biofuels by using hydrophobic zeolites acting as PE stabilizers.…”