Easy Product Separation

Biphasic catalysis in a liquid-liquid system is an ideal approach through which to combine the advantages of both homogeneous and heterogeneous catalysis. The reaction mixture consists of two immiscible solvents. Only one phase contains the catalyst, allowing easy product separation by simple decantation. The catalyst phase can be recycled without any further treatment. However, the right combination of catalyst, catalyst solvent, and product is crucial for the success of biphasic catalysis [22]. The catalyst solvent has to provide excellent solubility for the catalyst complex without competing with the reaction substrate for the free coordination sites at the catalytic center. 

Easy product separation and catalyst recycling Lower cost of chemical processes... 

It has also been suggested that solubihzation of enzymes in organogels allows interesting reaction media to be realized since they facilitate enzyme reuse and easy product separation [281],... 

Anchoring the catalyst to polymeric materials has some advantages in easy product separation and catalyst recovery for recycling. The first example of a polymer-supported rhodium catalyst for hydroformylation was reported in 1975. Since then, many reports have been published on polymer-supported catalysts here, we focus on examples of normal-sc QcxiY or enantioselective hydroformylation. 

In recent years, researchers have become increasingly interested in the use of carbon dioxide as a source of carbon because of its ideal properties as a Crunit in future chemistry 1-3], The three most important advantages are its abundancy, low cost and non-toxicity. Supercritical carbon dioxide (scC02) has also been considered as an ideal apolar solvent for chemical reactions due to its increased diffusion rates and reactant solubilities, and to its easy product separation compared to conventional solvents [4-7]. 

Turnover frequencies could be further increased (reaction rates as high as 7,500 mol mor lf1) if LiCl was added instead of an organic base, however at a pronounced cost to the selectivity. While a temperature of 50°C is required in toluene to activate the catalyst, complex 40 exhibits activity already at -10°C in the ionic liquid. This indicates that the in situ generation of the catalyst, which is believed to require the formation of a Ni-hydride complex, proceeds more efficiently in the ionic liquid. On the other hand, the use of aluminiumalkyles as the proton scavenger led to poor results and the catalyst decomposed rapidly at ambient temperature. The catalyst stability was sufficient at low temperature, -10°C, but the linear product was formed with only 12% selectivity under these conditions. The biphasic nature of the system allows for easy product separation and catalyst recycling. Accordingly, the performance was also tested in a continuous mode and catalytic activity was maintained for at least three hours.1 71 After that time,... 

Both reactions could be carried out in a liquid-liquid two-phase system with the advantages of easy product separation and efficient catalyst recycling. In the presence of a water-soluble ruthenium catalyst with the ligand triphenylphosphine trisulfo-nate, simultaneous extraction of the organic product phase by N,N-dibutylformamide can be achieved [87, 88]. 

Water (-fco-solvent) Organic liquid Easy product separation and catalyst recycling Lower cost of chemical processes Lack of toxicity of water Low reaction rate for water poorly miscible substrates Mass transfer limits rate of reaction Treatment of spent water... 

CO2 as co-solvent In this case CO2 is present during the reaction to ensrue the solubilization of the catalyst After the reaction, CO2 is released leading to catalyst precipitation and easy product separation. 

In vitro biosystems for biomanufacturing feature several industrial production advantages over whole-cell-based biomanufacturing. High product yield is accomplished by the elimination of side reactions and no synthesis of cell mass fast volumetric productivity can be achieved due to the better mass transfer without the barrier of cell membranes easy product separation can be achieved without cell membranes enzymes usually tolerate toxins and solvents much better than whole cells because of a lack of labile cell membranes the reconstitution of synthetic enzymatic pathways can implement some non-natural reactions that could never occur in living cells the reaction equilibrium may be shifted in favor of the product formation through well-designed synthetic enzymatic pathways. ... 

The Mizoroki-Heck reaction is usually performed in polar solvents, and salt additives such as tetrabutylammonium chloride have been shown to activate and stabihze the catalytically active palladium species [19]. Furthermore, the reactions in ionic hquids perform differently in terms of thermodynamic and kinetic properties of the reaction system. Additionally, ionic liquids allow a facile recovery of catalyst and substrates, as well as an easy product separation. Here, another beneficial effect might be used by combination of solvent mixtures for example, of ionic liquids and SCFs. SCFs and ionic liquids have a mixing gap which allows working in two-phase systems, and results in a straightforward phase separation [20]. 

Operated in biphasic system. No co-miscibility was observed between the products and the ionic liquids. Easy product separation by settling which does not require heating and results in energy saving and reduced catalyst consumption. 

The focus on lipase-catalyzed reaction in SC-CO2 is due to enhanced reaction rates (Lee et al, 2013). In biodiesel production systems, SC-CO2 offers easy product separation from the reaction mixture by selectively dissolving the biodiesel, due to its high solubility compared to the glycerol by-product (Rodrigues et al, 2011). In a continuous system, the product is continuously removed from the reaction system, which can then be easily separated from SC-CO2 by simple depressurization. 

Although the homogeneous reactions (Section 22.2.1) take place faster than the heterogeneous ones and a higher activity is found in the former case, the use of the PDMS-supported catalysts is promising, as it is based on cheap and easily obtained membrane and vanadium(IV) catalysts, involves a simple way to heterogenize the catalyst without its chemical modification, and allows an easy product separation [5b]. 

An elegant way to combine the advantages of homogeneous catalysis with an efficient strategy for catalyst recycling is hquid-liquid biphasic catalysis Only one phase contains the dissolved catalyst, allowing easy product separation by phase... 

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