Homogeneous hydroformylation reactions

This homogeneous hydroformylation reaction was conducted in a batch reactor, and because of the nature of the catalyst, isomerization reactions of 1-hexene to 2- and 3-hexenes and hydrogenation reactions of hexenes to hexanes and aldehydes to alcohols were minimized. The following data were obtained at 323 K with an initial concentration of 1-hexene at 1 mol/L in toluene and Pco... 

It has yet to be seen whether the principle of biphasic hydroformylation can be further extended beyond C4 olefins. Bearing in mind the advantages of biphasic operation, two pathways may be considered biphasic operation in the reactor section and subsequent phase separation or a combination of homogeneous hydroformylation reaction with an auxiliary agent. This substance would require a miscibility gap with the products under conditions different from the reaction conditions. Examples of both principal methods have already been published [271, 272]. However, a general solution is not to be expected, as each feed-stock/product pair requires a specially adapted solvent. Novel developments in the field of catalyst separation and reuse of catalyst systems are noted below. 

The improved catalytic efficiency of homogeneous hydroformylation reactions in CO2 has been proven... 

King RB, King AD Jr, Iqbal MZ (1979) ALkybhodium tetracarbonyl derivatives as catalytic intermediates in homogeneous hydroformylation reactions. An infrared spectroscopic study. J Am Chem Soc 101(17) 4893-4896... 

Hydroformylation represents the most industrially important homogeneous catalysed reaction by volume [2, 3]. The petrochemical, agrochemical and pharmaceutical industries are particularly interested in this transformation. The reaction uses syngas (COiH mix) and a catalyst, commonly rhodium or platinum, to transform an olefin into an aldehyde (Scheme 9.1) [4]. 

Hydroformylation is the oldest and in production volume the largest homogeneously catalyzed industrial process. The hydroformylation reaction was discovered by Otto Roelen in 1938 the reaction is also called oxosynthesis and Roden s reaction [1-13]. 

CH ligands, (2) to initiate homogeneous catalytic reactions such as hydrogenation, hydroformylation, and the water gas shift reaction, and (3) to study the mechanism of thermal reactions by the photochemical preparation of possible intermediates. 

In the early 1970 s, Bayer et al. reported the first use of soluble polymers as supports for the homogeneous catalysts. [52] They used non-crosslinked linear polystyrene (Mw ca. 100 000), which was chloromethylated and converted by treatment with potassium diphenylphosphide into soluble polydiphenyl(styrylmethyl)phosphines. Soluble macromolecular metal complexes were prepared by addition of various metal precursors e.g. [Rh(PPh3)Cl] and [RhH(CO)(PPh3)3]. The first complex was used in the hydrogenation reaction of 1-pentene at 22°C and 1 atm. H2. After 24 h (50% conversion in 3 h) the reaction solution was filtered through a polyamide membrane [53] and the catalysts could be retained quantitatively in the membrane filtration cell. [54] The catalyst was recycled 5 times. Using the second complex, a hydroformylation reaction of 1-pentene was carried out. After 72 h the reaction mixture was filtered through a polyamide membrane and recycled twice. 

Hildebrand parameter and high polarity advantageously influence organic chemical reactions (such as hydroformylation), has sufficiently high polarity and density differences compared to organic (reaction) products to enable separation of the phases after the homogeneously catalyzed reaction is completed [17]. 

Pettit and coworkers—metal hydride intermediates by weak base attack over Fe carbonyl catalysts. Pettit et al.ls approached the use of metal carbonyl catalysts for the homogeneous water-gas shift reaction from the standpoint of hydroformyla-tion by the Reppe modification.7 In the typical hydroformylation reaction, an alkene is converted to the next higher aldehyde or alcohol through reaction of CO and H2 with the use of a cobalt or rhodium carbonyl catalyst. However, in the Reppe modification, the reduction is carried out with CO and H20 in lieu of H2 (Scheme 6) ... 

Hydroformylation is the most successful application of a homogeneous catalytic reaction to industrial processes [1], Aldehydes are conveniently produced by hydroformylation, in which CO and hydrogen are simultaneously added to an alkene (Figure 1). 

The hydroformylation reaction that converts olefins into aldehydes is the largest volume homogeneous transition-metal catalyzed reaction used today. This reaction has been extensively studied and nowadays a number of efficient catalysts make it possible to control the regioselectivity of the reaction to give terminal or internal aldehydes (Scheme 1). 

There are many different homogeneous catalysts available that can be used for hydrogenation and hydroformylation reactions. The most widely used metals that are present in these catalysts are the transition metals, especially Co, Ni, Ru, Rh and Ir [1],... 

The catalytic cycle for hydroformylation reactions has also been established for certain homogeneous catalysts. Scheme 8.4 illustrates that for HRh(CO)2(PPh3)2, although the cycle is the same for the analogous cobalt catalyst. 

Chlorostannate ionic liquids have been used in hydroformylation reactions [23], Acidic [bmimjCl-SnCb and [l-butyl-4-methylpyridinium]Cl-SnCl2 were prepared from mixing the respective [cation]+ Cl with tin(II)chloride in a ratio of 100 104, much in the same way that the chloroaluminates are made (see Chapter 4). Both these chlorostannate ionic liquids melt below 25 °C. Addition of Pd(PPh3)2Cl2 to these chlorostannate ionic liquids leads to a reaction medium that catalyses the hydroformylation of alkenes such as methyl-3-pentenoate as shown in Scheme 8.9. The ionic liquid-palladium catalyst solution is more effective than the corresponding homogeneous dichloromethane-palladium catalyst solution. The product was readily separated from the ionic liquid by distillation under vacuum. This is an important reaction as it provides a clean route to adipic acid. 

With an annual production of up to 9.3 million tons in 1998, hydroformylation is the most important homogeneously catalyzed reaction [20,21], The reaction is performed almost exclusively by the use of cobalt or rhodium catalysts. The advantages of rhodium catalysts are milder reaction conditions and better n/iso ratios in product distribution. The toxicity of rhodium compounds as well as the high rhodium price [22] (between 20 and 75 g during the last five years) demand an efficient catalyst recycling. 

The hydroformylation of olefins discovered by Otto Roelen [ 151 ] is one of the most important industrial homogeneously catalyzed reactions [152,153] for the synthesis of aldehydes with an estimated production of more than 9.2 million t in 1998 [ 153]. Hydroformylation is the addition of hydrogen and carbon monoxide to a C,C double bond. Industrial processes are based on cobalt or rhodiiun catalysts according to Eq. 1. The desired products are linear (n-) and branched (i-) aldehydes, in which the hnear products are generally favored for subsequent processing. 

The procedure has been successfully tested on synthetic data and applied to the homogeneous rhodium catalyzed hydroformylation reaction, where the 2D tracks for the peak center positions of both organometallic intermediates and products were identified. If the data is collected in a very small region of composition... 

An alternative interpretation of some features of the hydroformylation reaction (including the inverse CO dependence), in terms of heterogeneous catalysis by an (unidentified) insoluble cobalt component, has recently been advanced by Aldridge, Fasce and Jonassen (49a). The universal validity of this seems doubtful in the light of the considerable evidence favoring a homogeneous mechanism. 

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