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Iridium catalysis continued

Whereas most hydrogenation catalysts function very well in water (see for example Chapter 38 for two-phase aqueous catalysis), scattered instances are known of inhibition by water. Laue et al. attached Noyori s transfer hydrogenation catalyst to a soluble polymer and used this in a continuous device in which the catalyst was separated from the product by a membrane. The catalyst was found to be inhibited by the presence of traces of water in the feed stream, though this could be reversed by continuously feeding a small amount of potassium isopropoxide [60]. A case of water inhibition in iridium-catalyzed hydrogenation is described in Section 44.6.2. [Pg.1503]

It is now nearly 40 years since the introduction by Monsanto of a rhodium-catalysed process for the production of acetic acid by carbonylation of methanol [1]. The so-called Monsanto process became the dominant method for manufacture of acetic acid and is one of the most successful examples of the commercial application of homogeneous catalysis. The rhodium-catalysed process was preceded by a cobalt-based system developed by BASF [2,3], which suffered from significantly lower selectivity and the necessity for much harsher conditions of temperature and pressure. Although the rhodium-catalysed system has much better activity and selectivity, the search has continued in recent years for new catalysts which improve efficiency even further. The strategies employed have involved either modifications to the rhodium-based system or the replacement of rhodium by another metal, in particular iridium. This chapter will describe some of the important recent advances in both rhodium- and iridium-catalysed methanol carbonylation. Particular emphasis will be placed on the fundamental organometallic chemistry and mechanistic understanding of these processes. [Pg.187]

Coupling reactions of aromatic, heteroaromatic, and vinylic substrates with alkynes via sp C—H bond cleavage under rhodium, iridium, ruthenium, palladium, or nickel catalysis to produce a wide range of cyclic compounds have been described in this chapter. These annulation reactions provide powerful methods for constructing a variety of -rr-conjugated molecules containing fused aromatic and heteroaromatic nuclei from simple, readily available substrates. Extensive efforts will continue to be made to extend the scope of starting materials for this catalysis. [Pg.716]


See other pages where Iridium catalysis continued is mentioned: [Pg.39]    [Pg.342]    [Pg.297]    [Pg.186]    [Pg.357]    [Pg.207]    [Pg.339]    [Pg.343]    [Pg.356]    [Pg.394]    [Pg.237]    [Pg.443]    [Pg.364]   


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Catalysis continued

Iridium catalysis

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