Water-soluble rhodium catalyst

About 86% of Hoechst s butanal is produced with the Rhc )ne-Poulenc water-soluble rhodium catalyst the remainder is stiU based on cobalt. 

Wender et al. reported a [5+2] cycloaddition in water by using a water-soluble rhodium catalyst having a bidentate phosphine ligand to give a 7-membered ring product (Eq. 4.69). This water-soluble catalyst was reused eight times without any significant loss in catalytic activity.133... 

Addition of arylboronic acids to aldehydes using recoverable, water-soluble rhodium catalysts has also been reported.396... 

Water-soluble reactive dyes, 9 465 Water-soluble rhodium catalyst, 19 647 Water-soluble silanols, 22 604 Water-soluble suture coating materials,... 

Similar to the above case, hydroformylation of 1-hexene using a water-soluble rhodium catalyst [RhH(CO)(TPPMS)3] gave lower yields when a-cyclodextrin was added to the biphasic reaction system [14]. Again, the reason was suspected in the interaction between the cyclodextrin and the rhodium catalyst. 

The [2+2+2] cyclotrimerization of triynes has been reported using rhodium catalysts <2003JA12143> under biphasic conditions. Thus, the cyclization of triyne 174 proceeds rapidly in a biphasic system to produce the tricyclic compound in good yield using an in t/r -generated water-soluble rhodium catalyst (Equation 108) <2003JA7784>. 

Mercier, C. and Chabardes, P. (1995) Organometallic chemistry in industrial vitamin A and vitamin E synthesis. Chem. Ind. (Dekker) Catal. Org. React., 62, 213. Fremy, G., Castanet, Y., Grzybek, R., Monflier, E., Mortreux, A., Trzedak, A.M. and Ziolkowski, J.J. (1995) A new, highly selective, water-soluble rhodium catalyst for methyl acrylate hydroformylation. /. Organomet. Chem., 505, 11. 

Baidossi, W., Goren, N. and Blum, J. (1993) Homogeneous and biphasic oligomerization of terminal alkynes by some water soluble rhodium catalysts. J. Mol. Catal. A Chem., 85, 153. 

Reaction in two-phase liquid-liquid systems. The Ruhrchemie process for the manufacture of butyraldehyde from propylene uses a water-soluble rhodium catalyst, while the product butyraldehyde forms an immiscible organic layer. Separation of the product from the catalyst is thus easily accomplished (see Section 5.2.5). 

A first attempt at hydroformylation in a micellar system using a water-soluble rhodium catalyst (Rh-TPPTS) was made by Tinicci and Platone from Eniricerche in 1994 [ 59 ]. They converted olefins with carbon numbers up to 12 using a mixture of an anionic surfactant (SDS) and butanol (as co-surfactant). It has been shown that microemulsions made with non-ionic surfactants of the alcohol ethoxylate type are advantageous compared to ionic... 

Without a doubt, the most successful demonstration of aqueous catalysis has been the hydroformylation of low molecular weight terminal alkenes. The use of an aqueous biphasic medium to separate catalysts from products for this process was first envisioned by Kuntz at Rhone-Poulenc this eventually led to the development of a water-soluble rhodium catalyst [46] (cf. Section 6.1.1). 

The inverse temperature dependence of the water-solubility of nonionic tenside phosphines at the Tp was applied by Bergbreiter et al. [41] in the hydrogenation of allyl alcohol using water-soluble rhodium catalysts modified with the smart ligand 15 in aqueous media. In this case, on heating the sample to 40-50°C the reaction stopped but on cooling to 0 °C hydrogenation was resumed in the aqueous phase (cf. Section 4.6.3). 

Ruhrchemie AG was the first to seize upon the idea of applying a water-soluble rhodium catalyst and thus commercialize a process which has been elaborated on a laboratory scale by Rhone-Poulenc earlier [13, 14]. It took only two years of intensive research to develop the technical concept and to erect the first plant, which went on-stream in 1984 [15]. By 1987 the second unit was already built and today the total capacity for n-butyraldehyde amounts to more than 350000 tons per year [16, 17]. An additional plant for the production of n-pentanal from n-butene was brought on-stream in 1995 (see Section 6.1.3.1.8). 

Hydroformylation or oxosynthesis is a well-known homogeneous, transition metal catalyzed reaction which has known considerable and continuous development since its discovery by Otto Roelen in the laboratories of Ruhrchemie AG in 1938 [1], This reaction, which can be considered as the addition of a formyl group and hydrogen to a double bond, has been successfully applied in the industrial context by using two basic processes the homogeneous process where the rhodium or cobalt catalyst and the substrate are in the same phase (Shell, UCC, BASF, RCH processes) [2] and the aqueous/organic biphasic process where the water-soluble rhodium catalyst and the organic compounds are in two different phases (Ruhr-chemie/Rhone-Poulenc process) [3]. 

Another possible way to separate they catalyst from the fatty products was found by Davis [52-54] and further investigated by Fell [55]. This new method is supported aqueous-phase catalysis (SAPC cf. Section 4.7). On a hydrophilic support, e.g., silicon oxide with a high surface area, a thin aqueous film is applied which contains the water-soluble rhodium catalyst, for instance HRh(CO)L3 with sodium TPPTS ligands. Oleyl alcohol and syngas react at the organic/aqueous interface and form the formylstearyl alcohol in a yield of 97%. The catalyst can be separated from the product by simple filtration without loss of activity. 

In situ preparation of a water-soluble rhodium catalyst from [RhCl(COD)]2... 

Transition metal catalysed [2 + 2 + 2] cyclotrimerization of alkynes is a powerful tool to construct substituted aromatic compounds.[1] Recently, cyclotrimerization of alkynes in a water-ether biphasic system with the use of a water soluble rhodium catalyst has been reported.[2,3] Distribution of a hydrophobic substrate between the two phases keeps the concentration of substrate in the aqueous phase low. The biphasic system enables medium and large-sized ring systems to be synthesised on the basis of the concentration control. 

IN SITU PREPARATION OF A WATER-SOLUBLE RHODIUM CATALYST FROM [RhCl(COD)]2 AND TRISODIUM SALT OF TRIS(m-SULFONATOPHENYL)PHOSPHINE (tppts)... 

Rhone-Poulenc and Ruhrchemie (now Hoechst) developed a process in the 1980s based on a water soluble rhodium catalyst modified with triphenylphosphine sulphonate ligand that can produce normal to iso ratios as high as 20. Previous phosphine modified rhodium catalysts were oil soluble. 

Another alternative for catalyst separation is the filtration after the catalyst has been precipitated. An interesting application is given by Fell and co-workers [35] for the hydroformylation of higher olefins by a methanol- and water-soluble rhodium catalyst. As shown in Figure 5, the reaction is carried out in a homogeneous methanol solution. After distillation of the methanol the catalyst is precipitated, filtered off, and again prepared with the distilled methanol. The products leave the process after the filtration step. 

Ruhrchemie AG was the first to seize upon the idea of applying a water-soluble rhodium catalyst and thus commercializing a process which had been elaborated on a laboratory scale by Rhone-Poulenc earlier [15, 16]. 

Andersson and coworkers coupled triphenylphosphine to poly(acrylic acid) and polyethylenimine, respectively (Scheme 2.42) [148]. The corresponding water-soluble rhodium catalysts were used in the gas-phase hydroformylation of propene and in the fiquid-phase reaction of 1-octene. By addition of a micelleforming additive (e.g., SDS (sodium dodecyl sulfate)), the latter transformation could be significantly accelerated. 

Scheme 7.5 Aqueous two-phase hydroformylation with a water-soluble rhodium catalyst and an additional promoter ligand.

Gassner, F. Leitner, W. (1993) C02-activation. 3. Hydrogenation of carbon-dioxide to formic acid using water-soluble rhodium catalysts, Chem. Commun., 1465-6. 

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