Hydroformylation Union Carbide Corporation

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. 

LPO process. Propene hydroformylation can be done with a rhodium triphenylphosphine catalyst giving a linearity ranging from 60 to 96 % depending on the phosphine concentration. At very high phosphine concentration the rate is low, but the linearity achieves its maximum value. The commercial process (Union Carbide Corporation, now Dow Chemicals) operates presumably around 30 bar, at 120 °C, at high triphenylphosphine concentrations, and linearities around 92%. The estimated turnover frequency is in the order of only 300 mol(product).mol 1 (Rh).h Low ligand... 

The second generation of hydroformylation catalysts consists of rhodium complexes containing phosphorus ligands, and these catalysts were developed by researchers at Celanese Corporation and then Union Carbide Corporation in the 1970s. These reactions occurred with lower pressures of CO and this class of hydroformylation was called the "low-pressure 0x0" process. This process has been industrially attractive because the lower pressure of CO reduces capital and operating costs, and tihe presence of phosphorus ligands on rhodium has allowed for the fine-tuning of rates and selectivities. 

Rhodium-catalyzed hydroformylation using catalysts modified with alkylphosphines and arylphosphines was reported by Wilkinson s group [12]. Phosphine ligand variation hardly affected the rate and selectivity under the circumstances used (70 °C and 100 bar). Pruett (Union Carbide Corporation) found that phosphites can also be used, and the type of phosphite had a profound effect on rates and selectivities [13]. 

Rhodium, besides cobalt, is the only metal that is used in technical-scale hydroformylation. Because of the classification of industrial hydroformylation processes made by Cornils [1], with rhodium, the third generation, after two generations of Co-based hydroformylation, process was ushered. The first plants went on stream in the 1970s (1974 Ruhrehemie (nowadays Celanese) 1976 Union Carbide Corporation (nowadays Dow) 1978 Mitsubishi Chemical Corporation). These units operate with P-ligand-modified Rh catalysts at low... 

Besides P(OPh)3, the prototype of all monophosphites is tris(2,4-di-tert-butylphenyljphosphite (1) [3]. In 1981, the first ligands of this type were claimed for hydroformylation by Shell [4] and Union Carbide Corporation (UCC, since 2001 Dow Chemical) [5]. They are widely used in laboratories. 

Union Carbide Corporation was working on a low-pressure hydroformylation process as early as 1967, and used a rhodium carbonyl catalyst modified with a triphenyl phosphine ligand. " The ligand dramatically improved the normal/iso-aldehyde ratio of the product when compared to the free metal carbonyl. Reduced operating temperatures and pressures, low by-product formation, and the elimination of metallic rhodium deposition were also achieved. By 1975, a plant was operating using this catalyst, and the process was being licensed for the hydroformylation of propylene. 

In the mid-1960s, Wilkinson revealed that aryl phosphines are suitable for Rh-catalyzed hydroformylation. Subsequently, research mainly focused on metal rhodium [5]. As a result, the replacement of rhodium-phosphine complex catalytic process by Co-based process pushed the science and technology of olefin hydroformylation rapidly forward. The homogeneous catalytic process of UCC (Union Carbide Corporation, now Dow Chemical) is often referred to as the LPO (low-pressure 0X0) process. The reaction conditions then become easy. The conversion rate of olefin and the selectivity of aldehyde increase greatly. 

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