Combined catalysis

We thank the Dutch National Science Foundation (NWO-CW VICI and TOP grants) and the Research School Combination Catalysis (NRSC-C) for financial support. [1]... 

Katasorbon A process for removing carbonyl sulfide and other organic sulfur compounds from syngas by combined catalysis and adsorption. Offered by Lurgi. 

The workshop was organized by the NRSC-Catalysis (National Research School Combination Catalysis) of The Netherlands within the framework of the activities of the EU Network of Excellence (NoE) IDECAT (Integrated Design of Catalytic Nanomaterials for a Sustainable Production). 

The combined catalysis by 18-crown-6 and tetra-n-butylammonium bromide produces higher yields in shorter reaction times than either of the catalysts separately (Table 3.7) [21] and almost quantitative yields have been reported for solid solid liquid triphase catalysed esterification using silica impregnated with tetramethylammonium chloride [22]. 

More synthetic interest is generated by the potentially very useful hydration of dienes. As shown on Scheme 9.6, methylethylketone (MEK) can be produced from the relatively cheap and easily available 1,3-butadiene with combined catalysis by an acid and a transition metal catalyst. Ruthenium complexes of several N-N chelating Hgands (mostly of the phenanthroline and bipyridine type) were found active for this transformation in the presence of Bronsted acids with weakly coordinating anions, typically p-toluenesulfonic acid, TsOH [18,19]. In favourable cases 90 % yield of MEK, based on butadiene, could be obtained. 

We would like to thank all the people who have worked with us on various systems showing the effects of lateral interactions. We are especially grateful for many stimulating discussions with Drs. J.J. Lukkien and M.T.M. Koper, and Profs. R.A. van Santen and J.W. Niemantsverdriet. Our research was financially supported by the National Research School Combination Catalysis (NRSC-C). 

Another interesting alternative combines catalysis and electrochemistry [35]. In the reductive coupling cycle of two bromobenzene molecules to biphenyl, the Pd catalyst provides just two electrons. This reaction can be performed in an electrochemical cell, where the electrons are supplied from an outside source [36]. We thus see that catalysis gives us a variety of green alternatives to the classic stoichiometric process. There are no hard and fast rules as to which route to choose - it all depends on the reaction conditions, and on the chemicals available. 

In 1992, BASF opened a 35 000 tons per year ibuprofen production plant in Bishop, Texas. This plant was the result of the elegant green chemistry route developed by the BHC consortium. The clean synthesis of ibuprofen is an excellent example of how combining catalysis and green chemistry can yield both commercial success and environmental benefits. Ibuprofen is a nonsteroidal, anti-inflammatory painkiller. It is a popular over-the-counter drug against headache, toothache, and muscular pains. You may know it better as Advil , Motrin , or Nurofen. 

IFP Ethers Refinery C4 and C5 streams CATACOL technology combines catalysis and distillation separation 26 1996... 

IFP Ethyl tertiary butyl ether (ETBE) FCC and steam-cracker C4 cuts and ethanol CATACOL technology ensures hirjt ETBE yields by combining catalysis and distillation separation 3 1996... 

We acknowledge the many contributions of and discussions with our colleagues Jef Vekemans, Anja Palmans, Felix Beijer, Ronald Lange, and Ky Hirsch-berg. The research presented has been supported by the Eindhoven University of Technology, DSM Research, and The Netherlands Organization for Chemical Research (CW), with financial aid from The Netherlands Organization for Scientific Research (NWO), the National Research School Combination Catalysis (NSRC-C), and the Dutch Polymer Institute. 

A further aspect to be considered is that supported ILs can also host chemicals, for example, complexing agents, which could further enhance the selectivity in the separation. This concept opens up the possible use of ILs supported on a membrane, particularly ceramictype nano-membranes (e.g., an alumina nanoporous membrane obtained by anodic oxidation) to develop novel systems that can combine catalysis and separation. The concept is shown in Figure 2.14. 

Figure 2.14 Concept of using ionic liquids (hosting organometallic catalytic complexes) supported on an alumina nano-membrane to develop novel systems that can combine catalysis and separation.

The easiest technique to combine catalysis in a polar medium with product separation is shown in Figure 1. Both operations are done in the same unit at the same time. The nonpolar product phase is deposited from the polar catalyst phase and can be separated at the top of the reaction column. The SHOP oligomerization of ethene works in this way. The catalytic phase, consisting of 1,4-butanediol and nickel catalyst, always remains in the reaction unit. In the technical plant the reaction takes place not in only one reactor but in a series of tanks. This is so that the heat of reaction may be removed by water-cooled heat exchangers which are placed between the different reactor tanks. The flow scheme of the SHOP process is shown in Section 7.1. 

Combined catalysis by palladium(II) chloride and copper(II) chloride induces the reaction of 1-alkynes with oxygen and carbon monoxide at room temperature to give a... 

Since the seminal contributions in the 1980s of Breslow [la] for the Diels-Alder reaction and Kuntz and Ruhrchemie for hydroformylation reactions [lb], there has been an upsurge in interest in using water as the solvent, not only to enhance the reaction rates, but also to perform organic reactions that would otherwise be impossible, or to elicit new selectivities. Several reviews have been devoted specially to such a use [2], which nevertheless does not exclude the possibility of further catalyzing the reactions with Lewis acids [3] or the use of Lewis acid-surfactant-combined catalysis (LASC) [4],... 

The simplest way to combine catalysis in a polar medium and product separation is shown in Figure 1, where both operations proceed in one unit. The nonpolar phase can be separated at the top of the column while the polar catalyst phase remains in the reactor. This principle is realized in the SHOP process using 1,4-butanediol with a nickel catalyst as the catalytic phase. 

I Ls, when used as solvents, offer the possibility of combining catalysis with various other processes. Owing to their inherent conductivity, they are promising solvents for electrosynthesis. They avoid the addition of a supporting electrolyte and may... 

Skraup synthesis. It has now been reported that a convenient and cost effective preparative method results by using silver-loaded titania as the photocatalyst. In a similar way, n-nitroanilines are reduced to 1,2-phenylendiamines on Pt-loaded Xi02. Under these conditions condensation and dehydrogenation ensue leading to 2-arylbenzimidazoles in a convenient one-pot procedure that combines catalysis and photocatalysis (see Scheme 4). °... 

An interesting approach combines catalysis by nanoparticles with catalyst recycling in fluorous biphasic systems. Palladium nanoparticles were... 

Coupling Membranes and Reaction A catalytic membrane reactor combining catalysis and separation in one reactor is an excellent example of such a hybrid reactor (Figure 4.10.73), although this system is not yet used commercially. The potential of this concept has been demonstrated by the example of the catalytic dehydrogenation of ethane, which was investigated on the bench scale (Champagnie, Tsotsis, and Minet, 1990 Moulijn, Makkee, and Van Diepen, 2004) ... 

Catalytic Distillation Catalytic or reactive distillation is another example of the use of a hybrid reactor and combines catalysis and distillation in one column/reactor. Usually, we have a two-phase process with gas and liquid flowing in countercurrent mode. This requires special catalysts and packings, for example, monoliths, as in case of a fixed-bed flooding of the reactor would occur at high flow rates. In industry, catalytic distillation is already used for the production of MTBE (methyl tert-butyl ether), an important octane booster (Figure 4.10.77 DeGarmo, Parulekar, and Pinjala, 1992), cumene (DeGarmo, Parulekar, and Pinjala, 1992), and ethylbenzene (Podrebarac, Ng, and Rempel, 1997). 

This modified catalyst capillary was applied in on-column reaction gas chromatography. As this efficient technique combines catalysis and analysis in one single step, in situ reaction monitoring is possible. 

The combination of organocatalysis and metal catalysis in one pot provides high efficiency in organic synthesis [34]. Combination catalysis usually leads to a cascade reaction, in which each step is catalyzed by a certain catalyst, either an organocatalyst or a metal catalyst. The key to designing such catalysis is that both the metal catalyst and organocatalyst should tolerate each other when they catalyze different types of reactions. 

Enantioenriched indolines are very important compounds, which exist extensively in natural alkaloids or unnatural bioactive compounds. The development of facile methods toward chiral indolines continues to be a challenge for organic chemists. Unprotected indole 106 could be considered as a special enamine in an aromatic system. Inspired by the possible shift between enamine and imine of indole in the presence of strong acid. Sun and Chen et al. envisioned that a direct reduction of indole 106 to indoline 107 by a combined catalysis of Lewis base and Br0nsted acid would be highly possible (Scheme 32.24). Indeed, using the strategy... 

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