Catalytic carbonylation reaction Hydroformylation reactions

Hydroformylation. Probably the best known catalytic carbonylation reaction is the hydroformylation, or 0x0 reaction, for producing aldehydes and alcohols from carbon monoxide, hydrogen, and olefins (eq. 9) (36). 

The use of catalytic SILP materials has been reviewed recently [10] covering Friedel-Crafts reactions [33-37], hydroformylations (Rh-catalyzed) [38], hydrogenation (Rh-catalyzed) [39,40], Heck reactions (Pd-catalyzed) [41], and hydroaminations (Rh-, Pd-, and Zn-catalyzed) [42]. Since then, the SILP concept has been extended to additional catalytic reactions and alternative support materials. In this paper we will present results from continuous, fixed-bed carbonylation and hydroformylation reactions using rhodium-based SILP catalysts as reaction examples demonstrating the advantages of the SILP technology for bulk chemical production. 

Monsanto acetic acid synthesis 4), and the hydroformylation or 0X0 reaction (5). A key mechanistic step in catalytic carbonylation reactions is the migration of an alkyl group onto an adjacent carbonyl ligand. This reaction involves the formation of a new carbon-carbon bond and has been termed a carbonyl insertion reaction since a CO ligand has been formally inserted into the transition metal-carbon (r-bond. Because of the industrial and commercial importance of these catalytic reactions, the search for stoichiometric systems in which this step can be observed directly has been, and still is, one of great endeavor. 

The term carbonylation was first used by W.Reppe while working with syngas and carbon monoxide chemistry at BASF during the 1930s and 1940s. Carbonylations are catalytic reactions in which carbon monoxide, alone or with other compounds, is incorporated in an organic substrate. There are three general types of carbonylation reactions Reppe reactions, hydroformylations, and Koch carbonylations. 

A practically more useful classification can be made in terms of the actual presence or otherwise of a ligand in the final product(s) of reaction (see Masters, 1981). In some cases the ligands are carried over intact in the products of catalytic cycles, such as CO in a catalytic carbonylation or hydroformylation, for example. 

Claver, C., Dieguez, M., Pamies, 0. and Castillon, S., (2006) Topics in Organometallic Chemistry, Catalytic Carbonylation Reactions, Asymmetric Hydroformylation, vol. 18, Springer GmbH, Berlin, p. 35. 

These sites must be considered to have different catalytic properties. The sites on top (Co atoms of low coordination) would be similar to that of the central atom of cobalt carbonyl complexes, and reactions on these should be similar to those in hydroformylation. Specifically, insertion reactions between n- and cr-ligands (CO... 

Rh, are the base of active catalysts for CO hydrogenation and the hydroformylation of olefins. The presence of several promoters modifies their catalytic behavior and synergic effects on the base-metal have been observed Table 8.5 illustrates several examples in which homonuclear or heteronuclear carbonyl compounds have been used in the preparation of Co- or Co-Rh-based catalysts for the CO hydrogenation and/or hydroformylation reactions. 

Ruthenium is not an effective catalyst in many catalytic reactions however, it is becoming one of the most novel and promising metals with respect to organic synthesis. The recent discovery of C-H bond activation reactions [38] and alkene metathesis reactions [54] catalyzed by ruthenium complexes has had a significant impact on organic chemistry as well as other chemically related fields, such as natural product synthesis, polymer science, and material sciences. Similarly, carbonylation reactions catalyzed by ruthenium complexes have also been extensively developed. Compared with other transition-metal-catalyzed carbonylation reactions, ruthenium complexes are known to catalyze a few carbonylation reactions, such as hydroformylation or the reductive carbonylation of nitro compounds. In the last 10 years, a number of new carbonylation reactions have been discovered, as described in this chapter. We ex-... 

The 7t ligands play important roles in a large number of homogeneous catalytic processes. Alkene polymerization and a variety of other reactions involve alkene coordination (see Chapters 6 and 7). As the name suggests, CO is the main ligand in carbonylation reactions (see Chapter 4). All four ligands CO, alkene, H , and PR3, play important parts in hydroformylation reactions (see Chapter 5). 

It is obvious that such equilibria would exist for all the other catalytic intermediates. The result of all this is coupled catalytic cycles and many simultaneous catalytic reactions. This is shown schematically in Fig. 5.5. The complicated rate expressions of hydroformylation reactions are due to the occurrence of many reactions at the same time. As indicated in Fig. 5.5, selectivity towards anti-Markovnikov product increases with more phosphinated intermediates, whereas more carbonylation shifts the selectivity towards Mar-kovnikov product. This is to be expected in view of the fact that a sterically crowded environment around the metal center favors anti-Markovnikov addition (see Section 5.2.2). 

In the Shell process (SHOP) phosphine-modified cobalt-catalyzed hydrofor-mylation is one of the steps in the synthesis of linear alcohols with 12-15 carbon atoms (see Section 7.4.1). Two important characteristics of this reaction should be noted. First, the phosphine-modified precatalyst HCo(CO)3(PBu3) is less active for hydroformylation than HCo(CO)4 but more active for the subsequent hydrogenation of the aldehyde. In this catalytic system both hydroformylation and hydrogenation of the aldehyde are catalyzed by the same catalytic species. Second, the phosphorus ligand-substituted derivatives are more stable than their carbonyl analogues at higher temperatures and lower pressures (see Table 5.1). 

The most intensely studied insertion reactions are those of CO into metal—carbon bonds to form metal acyls. These reactions are fundamental to industrially important catalytic reactions such as carbonylation and hydroformylations (Sections 22-5 and 22-6). 

A central metal ion usually has a pronounced effect on the reactivity of a coordinated ligand at the coordinated atom or atoms. An important reaction of this type which has synthetic value is the reaction of alkenes and alkynes with hydrogen and carbon monoxide in the presence of a metal carbonyl. This is actually the catalytic process of hydroformylation and, although catalysis is beyond the scope of this work, it is nevertheless of interest from the standpoint of ligand reactivity. The reaction of ethylene with hydrogen and carbon monoxide in the presence of HCo(CO)4 as a catalyst is proposed to proceed (at least formally) through the steps shown 1U13) ... 

Hydroformylation reactions are important from the industrial point of view and the two commonly used hydroformylation catalysts are either Rh or Co based. We thought it would be interesting to anchor a SiOs unit on a cobalt cluster via hydrosilylation. This would be a close model to a silica-supported cobalt cluster. Secondly, since the reactions of silanetriols have been demonstrated to afford three-dimensional metallasiloxanes, we anticipated that this silanetriol would react with substrates such as trialkylaluminums, affording cobalt carbonyl cluster anchored aluminosiloxanes. Such compounds would resemble a modified zeolite having on its surface catalytically active cobalt carbonyl moieties and might inspire the preparation of actual zeolite systems with these modifications. 

Walter Hleber (1895-1976) was a student of Rudolf Weinland, who performed early experimental work on Alfred Werner s theory of coordination compounds (Hauptvalenzen, Nebenvalenzen). Hieber received his Ph. D. in 1919 from Tubingen University on a topic concerning ferric complexes of hypophosphorous acid. He then developed metal carbonyl chemistry, mainly at Technische Hochschule Miinchen (1935-1964) he is now considered the pioneering researcher in this area of study. His name is associated with compounds like HCo(CO)4 and H2pe(CO)4 that are relevant to catalytic hydrogen-transfer reactions (hydroformylation Section 2.1.1). Nucleophilic addition to metal carbonyls, e. g., Fe(CO)5 -i-OH —> [(C0)4FeC(=0)0H] , is known as the Hieber base reaction (cf. [76]). 

The cobalt-catalyzed reaction of carbon monoxide and hydrogen with an alkene, hydroformylation, is an extremely important industrial process, but it occurs under vigorous conditions (200-400 bar, 150-200 °C) and is not a particularly selective reaction. In the presence of ligand-modified rhodium catalysts, however, hydroformylation can be carried out under extremely mild conditions (1 bar, 25 C). The catalytic activity of such rhodium complexes is in fact lO -Ky times greater than that of cobalt complexes and side reactions, such as hydrogenation, are significantly reduced. The reactivity of alkenes in hydroformylation follows a similar pattern to that observed in other carbonylation reactions, i.e. linear terminal alkenes react more readily than linear internal alkenes, which in turn are more reactive than branched... 

The vast majority of transition metal clusters contain carbonyl ligands, which have been shown in many cases to be fluxional on the metal skeleton of the cluster (40,41). Therefore, the most obvious reactions to be catalyzed by such clusters should be those involving carbon monoxide. In fact, catalytic carbonylations are frequently encountered with transition metal carbonyl cluster catalysts, but very often the carbonylation step is followed by a consecutive step, e.g., a hydrogenation step, to give an overall hydroformylation. Simple carbonylation reactions have nevertheless been observed for various structures. 

Silanes normally reduce aldehydes or ketones under catalytic conditions to the silyl ethers. However, with certain catalysts such as nickel sulfide,Co2(CO)8, or (Ph3P)3RhCl, carbonyl compounds react with silanes to yield an equilibrium mixture of enol silyl ethers (Scheme 17). In a similar vein, the silyl-hydroformylation reaction of cycloalkenes with CO and silanes may be a practical way to prepare enol silyl ethers. An example is the preparation of compound (49). Catalytic 1,4-hydrosilation of a, -un-saturated ketones or aldehydes gives the corresponding enol silyl ethers. The reaction is similar to the reductive silylation referred to previously, but the reaction conditions are neutral and milder. The formation of the enol silyl ether (50) is outlined below. ... 

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