Multiphase homogeneous catalysis

Table 5.3-1 Advantages and limitations of different approaches for multiphasic homogeneous catalysis.

B. Comils, W. A. Herrmann, I. T. Horvath, W. Leitner, S. Mecking, H. Olivier-Boubigou, D. Vogt (Eds. ), Multiphase Homogeneous Catalysis, Wiley-VCH, Weinheim 2004. 

CO oxidation, 38 236 differential heat of adsorption, 38 217 Biphasic systems, catalysis see Multiphase homogeneous catalysis BiPMo catalysts, 34 39 in formamide to nitrile reaction, 34 39 Bi-postdosing thermal desorption spectroscopy cyclohexene, 42 240... 

Multimetallic catalysts X-ray absorption smdies of, 34 271 Multiphase homogeneous catalysis, 42 473-474, 501... 

Multiphase homogeneous catalysis (continued) hydroformylation, 42 483-487, 498 hydrogenations, 42 488-491 metal salts as catalysis, 42 482-487 neutral ligands, 42 481 82 organic reactions, 42 495 0X0 synthesis, 42 483-487 ring-opening metathesis polymerization and isomerization, 42 492-494 telomerizations, 42 491-492 diols as catalyst phase, 42 496 fluorinated compounds as catalyst phase, 42 497... 

Vogt D, Horath J, Olivier-Bourbigou H, Leitner W, Mecking S (2005) In Cornils B, Hermann WA (eds) Multiphase Homogeneous Catalysis. Wiley, Weinheim... 

CornUs B, Herrmann WA, Vogt D, Horvath I, Olivier-Bourbigon H, Leitner W, Meck-ing S (eds) (2005) Multiphase homogeneous catalysis. WUey-VCH, Weinheim... 

Lubineau A, Auge J, Scherrmann M-C (2005) State of the art organic chemistry in water. In Comils B (ed) Multiphase homogeneous catalysis. Wiley, Weinheim Scherrmann M-C, Norsikian S, Lubineau A (2005) Solvophobic activation in organic synthesis. In Atta-ur-Rahman (ed) Advances in organic synthesis, vol. 1. Bentham Science... 

Notwithstanding the successes of multiphase homogeneous catalysis, many questions remain and research is needed. Reaction mechanisms and kinetics must be investigated to explain the observed changes in activity and selectivity when water-soluble catalysts are applied. 

Maase, M. (2005) in Multiphase Homogeneous Catalysis (eds B. Comils et oJ.), Wiley-VCH, Weinheim, Germany,... 

The following discussion shows that the industrial examples of multiphase homogeneous catalytic processes are those for which the limitations discussed above have been overcome. It is always necessary to have clearly in mind these limitations, otherwise it cannot be explained why, despite intense research in this area and the several claims of advantages in multiphase homogeneous catalysis operations, the number of industrial applications is still quite limited. 

Fluorous biphasic catalysis is another active area in multiphasic homogeneous catalysis. The term fluorous was introduced [90] as the analogue to the term aqueous, to emphasize the fact that one of the phases of a biphase system is richer in fluorocarbons than the other. Fluorous biphase systems can be used in catalytic chemical transformations by immobilizing catalysts in the fluorous phase. A fluorous catalyst system consists of a fluorous phase containing a preferentially fluorous-soluble catalyst and a second product phase, which may be any organic or inorganic solvent with limited solubility in the fluorous phase (Figure 2.8a). 

Ionic liquids (IL) [92] are a major topic in the area of multiphase homogeneous catalysis. ILs are characterized by the following three criteria (i) consist entirely of ions, (ii) have melting points below 100 °C and (hi) exhibit no detectable vapor pressure below the temperature of their thermal decomposition. As a consequence of these properties most ions forming ionic liquids display low charge densities, resulting in a low intermolecular interaction. Figure 2.8b displays some of the most common ions used so far for the formation of ionic liquids. 

Conclusions on Multiphase Homogeneous Catalysis for Sustainable Processes... 

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