Hydroformylation Oxo-process

It closely resembles the Monsanto process but uses MeC02Me in place of MeOH. cM-[Rh(CO)2l2] remains the catalyst and 

Hydroformylation (or the Oxo-process) is the conversion of alkenes to aldehydes (reaction 27.20). It is catalysed by 

Just as we saw that the rate of hydrogenation was hindered by sterically demanding alkenes (Table 27.1), so too is the rate of hydroformylation affected by steric constraints, as is illustrated by the data in Table 27.4. 

Other hydroformylation catalysts that are used industrially are HCo(CO)3(PBu3) (which, like HCo(CO)4, must lose CO to become coordinatively unsaturated) and HRh(CO)(PPh3)3 (which loses PPh3 to give the catalytically active HRh(CO)(PPh3)2). Data in Table 27.5 compare the operating conditions for, and selectivities of, these catalysts with those of HCo(CO)4. The Rh(I) catalyst is particularly selective towards aldehyde formation, and under certain conditions the n i ratio is as high as 20 1. An excess of 

PPh3 prevents reactions 27.22 which occur in the presence of CO. The products of reactions 27.22 are also hydroformylation catalysts, but lack the selectivity of HRh(CO)(PPh3)2. The parent phosphine complex, HRh(PPh3)3, is inactive towards hydroformylation, and while RhCl(PPh3)3 is active, d acts as an inhibitor. 

Interpret the data in equation 26.18 into a form that gives an 

Draw out a catalytic cycle for the conversion of pent-l-ene to hexanal using HRh(CO)4 as the catalyst precursor. 

Chemoselectivity (aldehyde predominating over alcohol) High Low High 

Cobalt-based catalysts were the first to be employed. Under the conditions of the reaction (370-470 K, 100-400 bar). 

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The odd-carbon stmcture and the extent of branching provide amyl alcohols with unique physical and solubiUty properties and often offer ideal properties for solvent, surfactant, extraction, gasoline additive, and fragrance appHcations. Amyl alcohols have been produced by various commercial processes ia past years. Today the most important iadustrial process is low pressure rhodium-cataly2ed hydroformylation (oxo process) of butenes. 

Keywords Hydroformylation, Oxo process. Aqueous biphasic homogeneous catalysis. 

The most important and oldest application of aqueous biphasic, homogeneous catalysis is hydroformylation (oxo process, Roelen reaction). This process is used to produce n-butyraldehyde, the desired main product of the reaction of propylene, which is converted by aldolization into 2-ethyUiexenal and this is finally hydrogenated to give 2-ethylhexanol (2-EH), the most economically important plasticizer alcohol (Scheme 1) ... 

Hydroformylation of olefins. Hydroformylation (oxo process) is the oldest homogeneous catalysis of industrial importance. Whereas the combination of an olefin with H2 gives hydrogenation products, a mixture of H2 and CO, called synthesis gas, instead gives various products including hydrocarbons, methanol, ethylene... 

Hydroformylation (Oxo-process, O. Roelen, Ruhrchemie, 1938 worldwide there are three variants of the Oxo-process 1. the classical synthesis using HCo(CO)4 as catalyst 2. Shell s SHOP-process, based on a cobalt carbonyl - phosphine complex 3. UCC s process, using a rhodium catalyst). ... 

Aliphatic Aldehyde Syntheses. Friedel-Crafts-type aUphatic aldehyde syntheses are considerably rarer than those of aromatic aldehydes. However, the hydroformylation reaction of olefins (185) and the related oxo synthesis are effected by strong acid catalysts, eg, tetracarbonylhydrocobalt, HCo(CO)4 (see Oxo process). 

Ligand-Modified Rhodium Process. The triphenylphosphine-modified rhodium oxo process, termed the LP Oxo process, is the industry standard for the hydroformylation of ethylene and propylene as of this writing (ca 1995). It employs a triphenylphosphine [603-35-0] (TPP) (1) modified rhodium catalyst. The process operates at low (0.7—3 MPa (100—450 psi)) pressures and low (80—120°C) temperatures. Suitable sources of rhodium are the alkanoate, 2,4-pentanedionate, or nitrate. A low (60—80 kPa (8.7—11.6 psi)) CO partial pressure and high (10—12%) TPP concentration are critical to obtaining a high (eg, 10 1) normal-to-branched aldehyde ratio. The process, first commercialized in 1976 by Union Carbide Corporation in Ponce, Puerto Rico, has been ficensed worldwide by Union Carbide Corporation and Davy Process Technology. 

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. 

Propanol has been manufactured by hydroformylation of ethylene (qv) (see Oxo process) followed by hydrogenation of propionaldehyde or propanal and as a by-product of vapor-phase oxidation of propane (see Hydrocarbon oxidation). Celanese operated the only commercial vapor-phase oxidation faciUty at Bishop, Texas. Since this faciUty was shut down ia 1973 (5,6), hydroformylation or 0x0 technology has been the principal process for commercial manufacture of 1-propanol ia the United States and Europe. Sasol ia South Africa makes 1-propanol by Fischer-Tropsch chemistry (7). Some attempts have been made to hydrate propylene ia an anti-Markovnikoff fashion to produce 1-propanol (8—10). However, these attempts have not been commercially successful. 

Propane, 1-propanol, and heavy ends (the last are made by aldol condensation) are minor by-products of the hydroformylation step. A number of transition-metal carbonyls (qv), eg, Co, Fe, Ni, Rh, and Ir, have been used to cataly2e the oxo reaction, but cobalt and rhodium are the only economically practical choices. In the United States, Texas Eastman, Union Carbide, and Hoechst Celanese make 1-propanol by oxo technology (11). Texas Eastman, which had used conventional cobalt oxo technology with an HCo(CO)4 catalyst, switched to a phosphine-modified Rh catalyst ia 1989 (11) (see Oxo process). In Europe, 1-propanol is made by Hoechst AG and BASE AG (12). 

Butyra.Idehydes. Normal and isobutyraldehydes are produced from propylene by the oxo or hydroformylation process (see Oxo process). 

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,... 

Heptenes. Heptenes, are used for the preparation of isooctyl alcohol [26952-21-6] by hydroformylation (see Oxo process). The heptenes... 

A new homogeneous process for hydroformylation of olefins using a water-soluble catalyst has been developed (40). The catalyst is based on a rhodium complex and utilizes a water-soluble phosphine such as tri(M-sulfophenyl)phosphine. The use of an aqueous phase simplifies the separation of the catalyst and products (see Oxo process). 

Garbonylation of Olefins. The carbonylation of olefins is a process of immense industrial importance. The process includes hydroformylation and hydrosdylation of an olefin. The hydroformylation reaction, or oxo process (qv), leads to the formation of aldehydes (qv) from olefins, carbon monoxide, hydrogen, and a transition-metal carbonyl. The hydro sdylation reaction involves addition of a sdane to an olefin (126,127). One of the most important processes in the carbonylation of olefins uses Co2(CO)g or its derivatives with phosphoms ligands as a catalyst. Propionaldehyde (128) and butyraldehyde (qv) (129) are synthesized industrially according to the following equation ... 

Manufacturing procedures for most branched-chain acids are well known. For example, oxo process acids are manufactured from branched-chain olefins using hydroformylation followed by oxidation (3) (see Oxo process). 

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 ... 

C-19 dicarboxyhc acid can be made from oleic acid or derivatives and carbon monoxide by hydroformylation, hydrocarboxylation, or carbonylation. In hydroformylation, ie, the Oxo reaction or Roelen reaction, the catalyst is usually cobalt carbonyl or a rhodium complex (see Oxo process). When using a cobalt catalyst a mixture of isomeric C-19 compounds results due to isomerization of the double bond prior to carbon monoxide addition (80). 

Currently, worldwide production of aldehydes exceeds 7 million tons/year (1). Higher aldehydes are important intermediates in the synthesis of industrial solvents, biodegradable detergents, surfactants, lubricants, and other plasticizers. The process, called hydroformylation or more familiarly, the Oxo process, refers to the addition of hydrogen and the formyl group, CHO, across a double bond. Two possible isomers can be formed (linear or branched) and the linear isomer is the desired product for these applications. 

The first stage of the process is a hydroformylation (oxo) reaction from which the main product is n-butyraldehyde. The feeds to this reactor are synthesis gas (CO/H2 mixture) and propylene in the molar ratio 2 1, and the recycled products of isobutyraldehyde cracking. The reactor operates at 130°C and 350 bar, using cobalt carbonyl as catalyst in solution. The main reaction products are n- and isobutyraldehyde in the ratio of 4 1, the former being the required product for subsequent conversion to 2-ethylhexanol. In addition, 3 per cent of the propylene feed is converted to propane whilst some does not react. 

The synthesis of tetrahydrofuran derivatives from unsaturated alcohols via hydroformylation intermediates was developed many years ago. Moderate yields are obtained from but-2-en-l,4-diol (Scheme 54)94 but hydroformylation is not the major pathway when coniferyl alcohol is subjected to the oxo process (Scheme 55).9S A more complicated reaction is involved... 

Also referred to as the oxo process or hydrocarbonylation, hydroformylation is a route to producing an aldehyde from an alkene, hydrogen, and carbon monoxide. This process has been known for approximately 70 years, and it is still economically important because useful compounds are produced in enormous quantities by this means. The reaction is summarized by the following equation ... 

Biphasic techniques for recovery and recycle are among the recent improvements of homogeneous catalysis - and they are the only developments which have been recently and successfully applied in the chemical industry. They are specially introduced into the hydroformylation (or "oxo") reaction, where they form a fourth generation of oxo processes (Figure 5.1 [1]). They are established as the "Ruhrchemie/Rhone-Poulenc process" (RCH/RP) [2] cf. also Section 5.2.4.1), with annual production rates of approximately 800,000 tonnes y"1 (tpy). 

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