Thermoregulated Liquid/Liquid Catalyst Separation and Recycling

Abstract

Considerable effort has been done to overcome the loss of catalyst in homogeneously catalysed processes. In this contribution we describe five recycling concepts for thermoregulated catalyst separation and recycling: fluorous biphasic systems (FBS), thermoregulated phase transfer catalysis (TRPTC), soluble polymer-based catalysis, thermoregulated microemulsions and temperature-dependent multicomponent solvent systems (TMS). Each of these concepts has its own special advantages like low catalyst leaching or simple process engineering but also drawbacks like usage of expensive special solvents or complex and expensive catalysts. In this context, TMS systems exhibit most advantages of the other concepts combined with the possibility to use common and cheap solvents as well as numerous classical molecular catalysts. Therefore, TMS systems are expected to be one of the most promising thermomorphic recycling concepts for industrial scale.

Coordination Chemistry inside Polymeric Nanoreactors: Metal Migration and Cross-Exchange in Amphiphilic Core-Shell Polymer Latexes

“…This operating protocol differs from those previously applied in nanoreactor catalysis, which used either homogeneous conditions with catalyst recovery by precipitation/filtration or by ultrafiltration or aqueous biphasic conditions with separation/recovery by decantation, but with the catalytic act occurring either in the organic phase at high temperature by the thermomorphic approach [21,22] or at the water/organic interface [23][24][25][26][27]. The structure of the CCM polymers, made by a convergent one-pot three-step procedure using reversible addition-fragmentation chain transfer (RAFT) polymerization [28][29][30][31][32][33] through the "polymerization-induced self-assembly" (PISA) approach in aqueous dispersed media [34,35], is shown in Figure 1.…”

Improved Palladium‐Catalyzed Sonogashira Coupling Reactions of Aryl Chlorides

“…Its usage in coupling reactions offers several advantages including the possibility of catalyst recycling a) via extraction of the nonpolar product with nonpolar solvents from the reaction mixture [35] or b) as PC can form part of temperature-dependent multicomponent solvent systems (TMS systems). [36] To our delight the reaction proceeded with 1 mol % [PdCl 2 A C H T U N G T R E N N U N G (CH 3 CN) 2 ] and 8 mol % of phosphine ligand L1 in 76 % yield at 90 8C (Table 1, entry 1). [37] Unfortunately, decreasing the Pd/ligand www.chemeurj.org ratio from 1:8 to 1:3 lowered the product yield (Table 1, entries 2 and 3) significantly.…”

Novel Palladium‐Catalysed Hydroamination of Myrcene and Catalyst Separation by Thermomorphic Solvent Systems

“…In particular, fluorous biphasic systems (FBS), [19,20] thermoregulated phasetransfer catalysts (TRPTC) [21] , soluble polymer-based catalysts [22,23] and thermoregulated microemulsions [24,25] were described in the literature. Another solution to avoid the mass transfer limitations of non-polar starting compounds is the concept of thermomorphic multi-component solvent (TMS) systems, which still provide simple phase separation for catalyst recycling.…”

“…Another solution to avoid the mass transfer limitations of non-polar starting compounds is the concept of thermomorphic multi-component solvent (TMS) systems, which still provide simple phase separation for catalyst recycling. [25,26] This method was developed by our work-group and is based on the temperaturedependent miscibility gap of two or three solvent components. For example, a selected mixture of two liquid components, immiscible at room temperature, is heated to a higher reaction temperature, whereupon it forms only one liquid phase.…”