Rhodium catalysts complexes

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. 

Phosphine, amino-rhodium complexes catalysts, hydroformylation, 6,261 Phosphine, 3-aminopropyldimethyl-photographic fixer, 6,100 Phosphine, bis(2-carboxyethyl)methyl-photography... 

Similar reactions have been carried out on acetylene. Aldehydes add to alkynes in the presence of a rhodium catalyst to give conjugated ketones. In a cyclic version of the addition of aldehydes, 4-pentenal was converted to cyclopen-tanone with a rhodium-complex catalyst. In the presence of a palladium catalyst, a tosylamide group added to an alkene unit to generate A-tosylpyrrolidine derivatives. ... 

Hsu et al. [15] applied a bimetallic catalyst comprising rhodium and ruthenium for the hydrogenation to combine the high selectivity of the rhodium complex with the lower cost of the ruthenium complex. When the amount of each metal is identical, the catalytic activity of the bimetallic complex catalyst system was similar to that of the single rhodium-complex catalyst, containing... 

With a rhodium complex catalyst containing a chiral ligand dispersed in [BMIM]SbFg, the enantioselective hydrogenation of a-acetamidocinnamic acid to (5)-phenylalanine was achieved with 64% enantiomeric excess 112). [RuCl2( S)-BINAP]2 NEt3 in [BMIM]BF4 for (5)-naproxen synthesis gave 80% ee from 2-(6-methoxy-2-naphthyl) acrylic acid and isopropyl alcohol 214). 

It is also remarkable that the rhodium complex catalyst in the supported ionic liquid showed long-term stability, being used for 18 batches without any significant loss of activity. It was confirmed that no rhodium metal clusters were formed. However, acetone could be used to remove the ionic layer and its presence led to a total loss of activity. 

The synthesis of acetic acid (AcOH) from methanol (MeOH) and carbon monoxide has been performed industrially in the liquid phase using a rhodium complex catalyst and an iodide promoter ( 4). The selectivity to acetic acid is more than 99% under mild conditions (175 C, 28 atm). The homogeneous rhodium catalyst is also effective for the synthesis of acetic anhydride (Ac O) by the carbonylation of dimethyl ether (DME) or methyl acetate (AcOMe) (5-13). However, rhodium is one of the most expensive metals, and its proved reserves are quite limited. It is highly desirable, therefore, to develop a new catalyst as a substitute for rhodium. 

Similar reactions have been carried out on acetylene.563 In a cyclic version of the addition of aldehydes, 4-pentenal was converted to cyclopentanone with a rhodium-complex catalyst.564... 

An indirect method for the hydroformylation of olefins involves formation of the tri-alkylborane (5-12) and treatment of this with carbon monoxide and a reducing agent (see 8-26). Hydroacylation of alkenes has been accomplished, in variable yields, by treatment with an acyl halide and a rhodium complex catalyst, e.g.,587... 

In a manner similar to the four methods mentioned above, rhodium complex catalysts immobilized on silica modified by 2-(MeO)3Si(CH2)2C5H4N and (Me0)3Si(CH2)30C0CMe=CH2 using [Rh(CO)2Cl]2 as the precursor are prepared61. These immobilized pyridine-Rh complexes are shown to be active catalysts in the... 

Acetic acid (CH3COOH) is a bulk commodity chemical with a world production of about 3.1 x 106 Mg/year, a demand increasing at a rate of +2.6% per year and a market price of US 0.44-0.47 per kg (Anon., 2001a). It is obtained primarily by the Monsanto or methanol carbonylation process, in which carbon monoxide reacts with methanol under the influence of a rhodium complex catalyst at 180°C and pressures of 30-40 bar, and secondarily by the oxidation of ethanol (Backus et al., 2003). The acetic fermentation route is limited to the food market and leads to vinegar production from several raw materials (e.g., apples, malt, grapes, grain, wines, and so on). 

The low-pressure oxo process based on rhodium complex catalysts has largely replaced the older, high-pressure process, which used cobalt carbonyls as catalyst. The low-pressure process is operated at about 100°C and 200psig. A new generation oxo process with bisphosphite modified rhodium catalyst is shown schematically in Fig. 10.5. 

The facile changes of oxidation state exhibited by rhodium complex catalysts pointed the way to the employment of rhodium complexes in the photochemical decomposition of water."... 

Chiyoda and UOP jointly developed an improved methanol carbonyl-ation process on the basis of this supported rhodium complex catalyst the process is called the Acetica process. This process for the production of acetic acid has found several industrial applications in Asia. The process description emphasizes the use of a three-phase reactor, a bubble column, or gas-lift reactor. The reactor column contains a liquid, a solid catalyst, and a bubbling gas stream containing CO efficient dissolution of the gas in the liquid is ensured by the design, which minimizes gas-liquid mass transfer resistance. 

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