Rhodium water-soluble complexes

The prototype reaction was the hydroformylation of oleyl alcohol (water insoluble) with a water-soluble rhodium complex, HRh(C0)[P(m-C6H4S03Na)3]3 (Figure 6.5). Oleyl alcohol was converted to the aldehyde (yield = 97%) using 2 mol % Rh with respect to the substrate and cyclohexane as the solvent, at 50 atmospheres CO/H2, and 100°C. The SAPCs were shown to be stable upon recycling, and extensive work proved that Rh is not leached into the organic phase. Since neither oleyl alcohol nor its products are water soluble, the reaction must take place at the aqueous-organic interface where Rh must be immobilized. Also, if the metal catalyst was supported on various controlled pore glasses with... 

Water-soluble rhodium complexes bearing sulfonated triphenylphos-phine ligands can catalyze the reduction of cyclohexene in a two-phase system. It is also possible to use Wilkinson s catalyst [(Ph3P)3RhCl] for the hydrogenation of water-soluble olefins in an aqueous-benzene solvent system (46). 

The idea of applying water-soluble rhodium complexes as catalysts for the hydroformylation reaction [212, 213] was taken up and commercialized by Ruhrchemie AG for the hydroformylation of propene [269]. After only two years of development on the laboratory scale the first plant was erected in 1984, followed by rapid further increases in capacity to more than 600000 tons/year today [214]. An additional unit for the production of n-pentanal from n-butene has been brought onstream in 1995 [271, 294]. 

Joo et al. utilized the highly water-soluble rhodium complex [RhCl(CO)(TPPTS)2] for the polymerization of terminal alkynes (phenylacetylene and (4-methylphe-nyl)acetylene for the structure of TPPTS cf. Section 7.2.2.3) [150]. This catalyst selectively produces cis-transoid polymers at room temperature in homogeneous solution in water/methanol mixtures, as well as in biphasic mixtures of water and chloro-... 

Johnson-Matthey Co. has reported that oleic acid methyl ester or linoleic acid methyl ester can be hydroformylated in micellar media using a water-soluble rhodium complex of monocarboxylated triphenylphosphine 45 as catalyst. As a further example, polyunsaturated linolenic acid methyl ester can be hydroformylated to the triformyl derivative with a selectivity of 55% with a Rh/TPPTS catalytic system in the presence of CTAB (Scheme 1.23). ... 

Researchers have worked to alleviate the problems of separation and corrosion in processes such as the oxo process by designing catalysts that are confined in a separate phase from the reactants (see Section 14.2.4). A commercially successful approach for propene hydroformylation resulted from preparation of water-soluble rhodium complex catalysts by sulfonation of the phenyl rings of the triphenyl phosphine ligands. The catalyst is used in a reactor with two liquid phases the propene is concentrated in the organic phase and the catalyst in the aqueous phase near the interface. The CO -I- H2 is bubbled into a mixed reactor, and the two-phase liquid product flows to a settler the organic product flows to downstream separation devices, and the aqueous phase with the catalyst is recycled to the reactor. 

Interfacial kinetics of biphasic hydroformylation of 1-dodecene catalyzed by water-soluble rhodium complex have been studied by a combined numerical and experimental approach [54]. 

The substrate selectivity observed during the hydrogenation of a 1 1 mixture of olefins and the increase in the linear to branched aldehyde ratio during the hydroformylation of 1-octene were attributed to the formation of transient adducts between the substrate and a water-soluble rhodium complexes bearing /3-CD-modified diphosphines (Figure 18). ... 

Another example dealing with the use of a microemulsion as the reaction medium can be found in a patent issued by Tinucci Platone . Although in this patent the catalyst was not prepared by microemulsion, the reaction takes place in a microemulsion system. The catalyst, a water-soluble rhodium complex, was formed in situ. The reactants, i.e. alkenes, were also the constituents of the oil phase of the microemulsion. Conversions higher than 70 % were obtained while the structure of the microemulsion was still maintained. Beyond that conversion level, the microemulsion was destroyed, probably because the oil phase was modified during the catalytic reaction. 

Whereas water-soluble rhodium complexes catalyze the biphasic hydrogenation of various unsaturated substrates but rapidly form colloids, the addition of yd-CD has been shown to lead to efficient homogeneous catalytic systems [40]. For instance, in the absence of transfer agent, as reported by Larpent et al. [41], maleic acid is completely transformed in 83 h instead of a reaction time of 17 h with yd-CD. Similarly, the hydrosilylation reaction of an alkene catalyzed by a platinum precursor can be notably accelerated by the presence of yd-CD the case of a Lamoreaux Pt Pl catalyst is more spectacular since the yield can reach 100% in 12 min, whereas no transformation of the substrate occurs in 24 h in the absence of yd-CD [42]. 

The recycling of the catalyst has been examined just by reintroducing the aqueous phase containing the water-soluble rhodium complex and the permethylated j6-CD, since usually a loss of activity occurs. Results are shown in Tables 6 and 7 for four successive runs carried out with either oct-l-ene or dec-l-ene. 

The synthesis of aldehydes by hydroformylation of alkenes is an important industrial process discovered in 1938. The use of biphasic catalysis, which is a well-established method for the separation of the product and the recovery of the catalyst, was developed for this reaction in the Ruhrchemie-Rhdne-Poulenc process a water-soluble rhodium complex is used as catalyst - the reaction proceeding in water - and the organic layer is formed simply by the alkene reagent and the aldehyde products. Butanal is manufactured this way, but owing to the low solubility of longer olefins in water, this process is limited to C2-C5 olefins. To overcome this limitation, ionic liquids have been studied as a reaction solvent for this biphasic reaction. 

A recent breakthrough has been the use of two-phase technology, commercialized in the Ruhrchemie/Rhone Poulenc process, which uses a new water-soluble rhodium complex with polar SOsNa groups on the phenyl rings of the phosphine (TPPTS) [1]. 

Dessoudeix. M. Urrutigoity. M. Kaick, P. Catalytic activity enhancement of a cyclodextrin/water-soluble-rhodium complex system due to its gradual supramolecular organization in the interphase. Eur. J. Inorg. Chem. 2001. 

The selectivity to linear product is improved by using a cobalt trialkyl phosphine complex, but the major product is the corresponding alcohol. The use of rhodium triphenylphosphine hydrocarbonyl gives a still higher selectivity to linear aldehyde under milder conditions. These advantages are retained by using a water-soluble rhodium complex with sulphonated phosphane ligands, which provides a novel two-phase mode of operation (recently commercialized). ... 

Several examples of poly- and oligomerization of acetylenes are also quite typical. Water-soluble rhodium complexes with hydrophilic phosphine ligands catalyze the polymerization of arylacetylenes into stereoregular cis-oriented poly(arylacetylenes), which can further be selectively depolymerized on heating to provide a convenient method for the preparation of triaryl-benzenes [194]. Different types of product formed by regioselective di- and trimerization can be obtained by the reaction of such catalysts with other kinds of terminal acetylenes [195]. 

Water-soluble rhodium complexes catalyze the reduction of CO2 to formates even in such media as aqueous solutions of amines used to capture carbon dioxide from flue gases [198]. 

Purwanto, P. Delmas, H. (1995) Gas-liquid-liquid reaction-engineering hydroform-ylation of 1-octene using a water-soluble rhodium complex catalyst, Catal. Today, 24, 135 0. 

Piya-areetham P, Prasassarakich P, Rempel GL. Organic solvent-free hydrogenation of natural rubber latex and synthetic polyisoprene emulsion catalyzed by water-soluble rhodium complexes. J Mol Catal A Chem. 2013 372 151-159. 

The micellar effect in hydroformylation of 1-octene and 1-decene using water-soluble rhodium complexes with sulfonated diphosphanes in the presence of ionic surfactants and methanol in water was studied. The hydroformylation activities using cetyltrrmethylammonium hydrogen sulfate and methanol additives were found to be higher than those in experiments without these additives [101]. 

The water-soluble rhodium complex [Rh(p.-pz)(CO)(TPPTS)]2 (pz = pyrazolate) was used as catalyst precursor during the two-phase catalytic hydroformylation of different olefins at 100 °C, 50 bar (CO H2 = 1 1), 600 rpm, and substrate catalyst ratio of 100 1. A reaction order- 1-hexene > styrene > allylbenzene > 2,3-dimethyl-1-butene > cyclohexene-was found. The experiments also showed that the binuclear catalyst precursor was resistant to possible sulfur poisons [108]. 

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