Ionic technical potential

In a continuing effort to explore the fuU technical potential of supported ionic liquids the concept has been extended to continuous flow processes. The reactions studied were Rh-phosphine catalyzed hydroformylation of propene and Toctene using more technically attractive continuous flow fixed-bed reaction designs [91-93] (more detailed description of the reaction set-ups may be found in Refs. [94,95] for gas-phase reactions and in Ref [96] for liquid-phase reactions). 

Actually, it is quite likely that the first area of broader technical ionic liquid use will indeed be a non-synthetic application. Why Certainly not because non-synthetic applications have shown more potential, more performance, or more possibilities, but because many of these are relatively simple, with clearly defined technical targets. The improvement over existing technology is often based on just one or a very few specific properties of the ionic liquid material, whereas for most synthetic appli-... 

Several of the examples in Table 9-1 are looking quite promising for technical realization on a short to medium timescale. Other ideas are still in their infancy, and there is still a lot of potential for the development of other new non-synthetic applications of ionic liquids in the years to come. 

The possibility of adjusting solubility properties is of particular importance for liquid-liquid biphasic catalysis. Liquid-liquid catalysis can be realised when the ionic liquid is able to dissolve the catalyst, especially if it displays partial solubility of the substrates and poor solubility of the reaction products. Under these conditions, the product phase, which also contains the unconverted reactants, is removed by simple phase decantation. The ionic liquid containing the catalyst can then be recycled. In such a scenario the ionic catalyst solution may be seen as part of the capital investment for a potential technical process (in an ideal case) or at least as a working solution (only a small amount has to be replaced after a certain time of application). A crucial aspect of this concept is the immobilisation of the transition metal catalyst in the ionic liquid. While most transition metal catalysts easily dissolve in an ionic liquid without any special ligand design, ionic ligand systems have been applied with great success to... 

In SILP carbonylation we have introduced a new methanol carbonylation SILP Monsanto catalyst, which is different from present catalytic alcohol carbonylation technologies, by using an ionic liquid as reaction medium and by offering an efficient use of the dispersed ionic liquid-based rhodium-iodide complex catalyst phase. In perspective the introduced fixed-bed SILP carbonylation process design requires a smaller reactor size than existing technology in order to obtain the same productivity, which makes the SILP carbonylation concept potentially interesting for technical applications. 

Many types of membrane have been developed and each is adapted to a specific ion or a gas. Technically, it is a matter of developing an ionic material that permits the formation of a concentration equilibrium with specific ions such that if the activity of the ion on both sides of the membrane varies, a potential difference is generated. Measurements involve only ions that are free in solution. 

Although the deposition of metals from ionic liquids has been possible for over 50 years, to date no processes have been developed to a commercial scale. There are numerous technical and economic reasons for this, many of which will be apparent from the preceding chapters. Notwithstanding, the tantalizing prospect of wide potential windows, high solubility of metal salts, avoidance of water and metal/water chemistry and high conductivity compared to non-aqueous solvents means that, for some metal deposition processes, ionic liquids must be a viable proposition. 

Risk potential of the technical application of the ionic liquid (leakages, toxic and eco-toxic effects, fate of the compounds in the environment)... 

Metal ion and halide impurities are an issue in ionic liquids with discrete anions. As we have demonstrated in Chapter 11.5 Li+ (and K+) are common cationic impurities, especially in the bis(trifluoromethylsulfonyl)amides which typically contain 100 ppm of these ions from the metathesis reaction. Although Li and K are only electrodeposited in the bulk phase at electrode potentials close to the decomposition potential of the pyrrolidinium ions, there is evidence for the underpotential deposition of Li and K on gold and on other rather noble metals. For a technical process to deposit nickel or cobalt from ionic liquids the codeposition of Li and/or K, even in the underpotential deposition regime, has to be expected. 

It follows from [4.6.8ff] that the Interfacicd excess entropy cem in principle be obtained from the temperature dependence of the surface tension. Such experiments require some scrutiny both technically (how to prevent evaporation ) and interpretationally (now to account for the temperature coefficients of chemical potentials at fixed concentrations ). Detailed studies are welcome. However, one striking trend may be mentioned ). Adsorption of (at least some) non-ionics is accompanied by an increase of entropy, whereas for the cationic Cj TMA Br" a decrease is observed. Again, more systematic study seems appropriate, before... 

First, we like to discuss influences chi the computed electrostatic Qia gies, which are due to the technical prcxjedure by which the LPB equation is solved. A standard procedure to solve the LPB equation, vdiich we also use here, is to place the molecular system in the center of a finite lattice, where electrostatic potential, charges, dielectric constant and ionic strength are discretized. The size of the initially used lattice should be large enough that the electrostatic jx)tential vanishes nearly at the boundary. 

In this way a continuous dimerization was realized over 50 h time-on-stream producing A -dihydrodimethylmuconate in an overall TON of more than 4000 (product selectivity >90%). This clearly demonstrates the potential of the biphasic ionic liquid system to bring the Pd-catalyzed MA dimerization closer to a technical realization. 

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