Hydroformylation olefin

Kuntz subsequently showed that the RhCl (tppts) 3 catalyzed the hydroformylation of propylene in an aqueous biphasic system [29]. These results were further developed, in collaboration with Ruhrchemie, to become what is known as the Ruhrchemie/Rhone-Poulenc two-phase process for the hydroformylation of propylene to n-butanal [18, 19, 22, 30]. Ruhrchemie developed a method for the large scale production of tppts by sulfonation of triphenylphosphine with 30% oleum at 20 °C for 24 h. The product is obtained in 95% purity by dilution with water, extraction with a water insoluble amine, such as tri(isooctylamine), and pH-controlled re-extraction of the sodium salt of tppts into water with a 5% aqueous solution of NaOH. The first commercial plant came on stream in 1984, with a capacity of 100000 tons per annum of butanal. Today the capacity is ca. 400000 tpa and a cumulative production of millions of tons. Typical reaction conditions are T=120°C, P=50bar, CO/H2 = 1.01, tppts/Rh = 50-100, [Rh] = 10-1000 ppm. The RhH(CO) (tppts)3 catalyst is prepared in situ from e.g. rhodium 2-ethylhexanoate and tppts in water. 

The RCH/RP process (see Fig. 7.4) affords butanals in 99% selectivity with a n/i ratio of 96/4. Rhodium carry-over into the organic phase is at the ppb level. The process has substantial economic and environmental benefits compared with conventional processes for the hydroformylation of propylene using Rh or Co complexes in an organic medium [31]  

Based on the success of the RCH/RP process much effort was devoted to the development of new ligands that are even more efficient (see Fig. 7.5 for examples) [17]. However, to our knowledge they have not been commercialized, probably because they do not have a favorable cost/benefit ratio. 

The aqueous biphasic hydroformylation concept is ineffective with higher olefins owing to mass transfer limitations posed by their low solubility in water. Several strategies have been employed to circumvent this problem [22], e.g. by conducting the reaction in a monophasic system using a tetraalkylammonium salt of tppts as the ligand, followed by separation of the catalyst by extraction into water. Alternatively, one can employ a different biphasic system such as a fluorous biphasic system or an ionic liquid/scC02 mixture (see later). 

What about when the substrate and product are water soluble The problem of catalyst recovery in this case can be solved by employing inverse aqueous bi-phasic catalysis. An example is the hydroformylation of N-allylacetamide in an aqueous biphasic system in which the catalyst is dissolved in the organic phase and the substrate and product remain in the water phase. This formed the basis for an elegant synthesis of the natural product, melatonin, in which the aqueous solution of the hydroformylation product was used in the next step without work-up (Fig. 7.6) [32]. 

Cobalt was the first catalyst used in commercial applications of the oxo-synthesis. In order to stabilize the HCo(CO)4 catalyst, high pressures are necessary with a maximum n/i ratio of 80/20. In the Shell process,324,325,393 cobalt catalysts modified with alkylphosphines e.g. ( )3 ( 4 9) are more selective towards linear products but exhibit high hydrogenation activity and are therefore mainly used for the direct synthesis of long chain alcohols. 

Process Classical Ruhrchemie BASF I Cl Shell Ruhrchemie LPO-Processa Ruhrchemie Rhone-Poulenc (RCHIRP) Process 

Selectivity to aldehydes medium low high high high 

Sensitivity towards catalysts poisons low low high high no sensitivity 

Separation Catalyst/Product chemical thermal chemical thermal decantation 

Following the discovery of the RhH(CO)(PPh3)3 catalyst by Wilkinson, Celanese and Union Carbide independently developed a rhodium-based 0x0 process operating at mild reaction conditions and exhibiting high n/i ratios. The main limitation of the so-called Low Pressure Oxo (LPO) process is that it is applicable only to lower olefins (up to 1-pentene) because the catalyst is separated from the aldehyde products by distillation. In principle, aldehydes of up to 10 carbon atoms chain length can be distilled, but the temperatures required for the 

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Olefin-CO coploymers Olefin p-complexes Olefin Fibers Olefin hydroformylation Olefin hydrogenation Olefimc alcohols Olefin isomerization Olefin metathesis Olefin oligomers Olefin oxides... 

Rhodium Ca.ta.lysts. Rhodium carbonyl catalysts for olefin hydroformylation are more active than cobalt carbonyls and can be appHed at lower temperatures and pressures (14). Rhodium hydrocarbonyl [75506-18-2] HRh(CO)4, results in lower -butyraldehyde [123-72-8] to isobutyraldehyde [78-84-2] ratios from propylene [115-07-17, C H, than does cobalt hydrocarbonyl, ie, 50/50 vs 80/20. Ligand-modified rhodium catalysts, HRh(CO)2L2 or HRh(CO)L2, afford /iso-ratios as high as 92/8 the ligand is generally a tertiary phosphine. The rhodium catalyst process was developed joindy by Union Carbide Chemicals, Johnson-Matthey, and Davy Powergas and has been Hcensed to several companies. It is particulady suited to propylene conversion to -butyraldehyde for 2-ethylhexanol production in that by-product isobutyraldehyde is minimized. 

Functional Olefin Hydroformylation. There has been widespread academic (18,19) and industrial (20) interest in functional olefin hydroformylation as a route to polyfiinctional molecules, eg, diols. There are two commercially practiced oxo processes employing functionalized olefin feedstocks. Akyl alcohol hydroformylation is carried out by Arco under Hcense from Kuraray (20,21). 1,4-Butanediol [110-63 ] is produced by successive hydroformylation of aHyl alcohol [107-18-6] aqueous extraction of the intermediate 2-hydroxytetrahydrofuran, and subsequent hydrogenation. 

The switch from the conventional cobalt complex catalyst to a new rhodium-based catalyst represents a technical advance for producing aldehydes by olefin hydroformylation with CO, ie, by the oxo process (qv) (82). A 200 t/yr CSTR pilot plant provided scale-up data for the first industrial,... 

Olefin Hydroformylation (The Oxo Process). One of the most important iadustrial applications of transition-metal complex catalysis is the hydroformylation of olefins (23), ihusttated for propjdene ... 

Polymer-supported catalysts incorporating organometaUic complexes also behave in much the same way as their soluble analogues (28). Extensive research has been done in attempts to develop supported rhodium complex catalysts for olefin hydroformylation and methanol carbonylation, but the effort has not been commercially successful. The difficulty is that the polymer-supported catalysts are not sufftciendy stable the valuable metal is continuously leached into the product stream (28). Consequendy, the soHd catalysts fail to eliminate the problems of corrosion and catalyst recovery and recycle that are characteristic of solution catalysis. 

Hydro carbonylation of olefins, hydroformylation, hydroesterification and hy-droxycarbonylation are reactions which appear to be of particular interest. Indeed, they allow the simultaneous creation of a new C - C bond as well as the introduction of a functional group (aldehyde, ester and acids). One or two new stereogenic centres can thus be formed at the same time (Scheme 26). Despite the difficulty of using high carbon monoxide pressure, the aheady existing industrial processes prove that such reactions can be performed on a very large scale [107]. 

The positively charged phosphonium ligand was intercalated in the hectorite and was used to catalyze olefin hydroformylation.156 Cu(II)-exchanged clays were tested as catalysts in the cyclopropanation reaction of styrene with... 

Olefin-hydroformylation on Cobalt-FT-catalysts in 1938 Head of Research at the Ruhrchemie company until 1962 Early co-worker of Franz Fischer... 

Comparing heterogeneous Fischer-Tropsch synthesis with homogeneous olefin hydroformylation can be seen as a source for understanding catalytic principles, particularly because the selectivity is complex and therefore highly informative. Reliable analytical techniques must be readily available. 

Olefin formation, by reductive elimination of 3-hydroxysulfones, 72, 2 Olefins, hydroformylation of, 56, 1 Oligomerization of 1,3-dienes, 19, 2 Oligosaccharide synthesis on polymer support, 68, 2 Oppenauer oxidation, 6, 5 Organoboranes ... 

Another possible reason that ethylene glycol is not produced by this system could be that the hydroxymethyl complex of (51) and (52) may undergo preferential reductive elimination to methanol, (52), rather than CO insertion, (51). However, CO insertion appears to take place in the formation of methyl formate, (53), where a similar insertion-reductive elimination branch appears to be involved. Insertion of CO should be much more favorable for the hydroxymethyl complex than for the methoxy complex (67, 83). Further, ruthenium carbonyl complexes are known to hydro-formylate olefins under conditions similar to those used in these CO hydrogenation reactions (183, 184). Based on the studies of equilibrium (46) previously described, a mononuclear catalyst and ruthenium hydride alkyl intermediate analogous to the hydroxymethyl complex of (51) seem probable. In such reactions, hydroformylation is achieved by CO insertion, and olefin hydrogenation is the result of competitive reductive elimination. The results reported for these reactions show that olefin hydroformylation predominates over hydrogenation, indicating that the CO insertion process of (51) should be quite competitive with the reductive elimination reaction of (52). 

Both the rhodium and the cobalt complexes catalyze olefin isomerization as well as olefin hydroformylation. In the case of the rhodium(I) catalysts, the amount of isomerization decreases as the ligands are altered in the order CO > NR3 > S > PR3. When homogeneous and supported amine-rhodium complexes were compared, it was found that they both gave similar amounts of isomerization, whereas with the tertiary phosphine complexes the supported catalysts gave rather less olefin isomerization than their homogeneous counterparts (44, 45). 

Figure 9. Energetics of catalytic intermediates in olefin hydroformylation...

Since the 1-olefin concentration-dependent hydroformylation in the presence of the above catalyst system has a slightly higher activation energy of about 22 kcal mol-1, it is proposed that the ratedetermining step of selective terminal 1-olefin hydroformylation may involve a transition state leading to the formation of a 1-alkyl bis-(trans-phosphine)rhodium carbonyl hydride complex rather than the dissociation of the trisphosphine complex. 

Aqueous phase catalysis, supported, for green olefin hydroformylation, 12, 855 Aquo complexes, with Ru and Os half-sandwiches,... 

Liquid injection molding, for silicone rubbers, 3, 674—675 Liquid ligands, in metal vapor synthesis, 1, 229 Liquid-phase catalysis, supported, for green olefin hydroformylation, 12, 855 Lithiacarbaboranes, preparation, 3, 114 Lithiation, arene chromium tricarbonyls, 5, 236 Lithium aluminum amides, reactions, 3, 282 Lithium aluminum hydride, for alcohol reductions, 3, 279 Lithium borohydride, in hydroborations, 9, 158 Lithium gallium hydride, in reduction reactions, 9, 738 Lithium indium hydride, in carbonyl reductions, 9, 713—714... 

Formation of Optically Active Aldehydes in Olefin Hydroformylation. 79... 

Table 9. Face of the Unsaturated Carbon Atom Prevailingly Attacked by CO in Internal Olefins Hydroformylation... 

The present authors feel this point needs further investigation in view of the results of Takegami et al. They found that the isomerization of the acylcobalt tetracarbonyl was very solvent-dependent, and it could well be that conditions in the hydroformylation of olefins and orthoformates were sufficiently different to cause faster isomerization in the former case. Thus, for example, the presence of olefins in the former case may contribute to a faster isomerization, or perhaps orthoformates, like tetrahydrofuran, inhibit the isomerization. A further factor to be considered is the presence of cobalt hydrocarbonyl, which must be present in larger amount in the case of olefin hydroformylation. Takegami et al. (143) have shown that cobalt hydrocarbonyl strongly promotes the isomerization of phenylacetylcobalt car-... 

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