Catalyzed Carbonylation of Methanol BPs Cativa Process

Iridium-Catalyzed Carbonylation of Methanol BP s Cativa Process 

Methanol carbonylation catalyzed by a combination of iridium-carbonyl compounds and iodide additives was first reported by Monsanto in the 1970s. The mechanism of this process was studied by Forster. ° In the 1990s, BP reported an improved catalyst system based on iridium and iodide that included a promoter, such as [Ru(CO)jy j. These Ir-based Cativa catalysts are about five times more active than the Rh catalysts, more stable in the presence of low amounts of water (5 wt %), and more soluble. In addition, Lr is usually less expensive than Rh. BP not only built new Cativa plants, but were able to convert existing plants containing rhodium catalysts to plants containing iridium Cativa catalysts because of the similarity of the Ir and Rh systems. 

there are many similarities between the mechanism of the Ir-catalyzed process and that of the Rh-catalyzed stystem, there are important differences. Unlike the dependence of the rate of the Monsanto process on only [Rh] and [CH I], the dependence of BP s iridium system on CO pressure, water, methyl acetate, methyl iodide, ruthenium promoter, and iridium are more complex and nonlinear. In situ IR spectroscopy of the iridium catalyst shows that the predominant species is the anionic Ir(III) methyl complex/flc,ds-[Ir(CH3)(CO)2y (2100 and 2047 cm ). Instead of occurring by turnover-limiting oxidative addition of Mel, the iridium-catalyzed process occurs by turnover-limiting insertion of CO into the metal-methyl complex. 

Hydroformylation of Olefins (Written with Prof. Charles P. Casey) 

Hydroformylation is a metal-catalyzed reaction in which an olefin, CO, and H react to produce an aldehyde. The reaction was discovered at BASF by Otto Roelen, and was called hydroformylation by Adkins. This transformation is also sometimes referred to as the oxo process. In a formal sense, the elements of formaldehyde are added across a C=C bond. Common side reactions include aUcene hydrogenation, aldehyde hydrogenation, and alkene isomerization. Hydroformylation is one of the largest volume reactions conducted with homogeneous catalysts in the chemical industry. It is used to produce over 14 billion pounds of aldehydes per year (two pounds per year for every person on Earth ). The aldehydes are converted to alcohols, acids, and other materials as useful end products. One large-volume use of hydroformylation is the conversion of propene to a mixture of -butyraldehyde and /-butyraldehyde (Equation 17.2). Since the desired product is n-butyraldehyde, a great deal of effort has been expended to maximize the n i (noimal to iso, or often also called l/b for linear to branched) ratio of aldehydes and to understand the factors that control it. 

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