Trisulfonated triphenylphosphine ligand

The aqueous-organic two-phase system was successfully applied to perform hydrocarboxylation.300 Palladium complexes of trisulfonated triphenylphosphine ligands were shown to exhibit high activity.301-303 The application of cosolvents and modified cyclodextrins allow to eliminate solubility problems associated with the transformation of higher alkenes.304... 

In order to keep the mild conditions, hydroxycarbonylation has been performed in biphasic media, maintaining the catalyst in the aqueous phase thanks to water-soluble mono- or diphosphine ligands. In the presence of the sodium salt of trisulfonated triphenylphosphine (TPPTS), palladium was shown to carbonylate efficiently acrylic ester [19], propene and light alkenes [20,21] in acidic media. For heavy alkenes the reduced activity due to the mass transfer problems between the aqueous and organic phases can be overcome by introducing an inverse phase transfer agent, and particularly dimeihyl-/-i-cyclodextrin [22,23]. Moreover, a dicationic palladium center coordinated by the bidentate diphosphine ligand 2,7-bis(sulfonato)xantphos (Fig. 2) catalyzes, in the presence of tolylsulfonic acid for stability reasons, the hydroxycarbonylation of ethylene, propene and styrene and provides a ca. 0.34 0.66 molar ratio for the two linear and branched acids [24],... 

The commercial success of rhodium-trisulfonated triphenylphosphine (TPPTS) catalysts1 has prompted considerable interest in TPPTS and other water-soluble ligands.2 The potential for new applications for the synthesis of both bulk and fine chemicals in water has led to methods for the preparation of a wide variety of sulfonated phosphines including chiral phosphines3 and... 

The Tsuji-Trost ally lie substitution catalyzed by Pd complexes using CH-acidic nucleophiles can be performed in an ionic liquid of type 1 alone [30] as well as in a biphasic system [31]. In the latter case the use of trisulfonated triphenylphosphine (TPPTS) prevents the catalyst from leaching into the organic phase. In comparison with water as the catalyst-supporting phase, the ionic liquid system exhibits higher activity and selectivity. The enantio-selective version of the allylic substitution with dimethyl malonate can also be performed in ionic liquids with a homochiral ferrocenylphosphine as the ligand [32]. 

Researchers at INTEVEP SA (Ven) have recently shown that the regioselective hydrogenation of benzo[fo]thiophene (BT) to dihydrobenzo[fo]thiophene (DHBT) (Eq. 2) can be performed in a 1 1 water/decalin mixture using an in situ catalyst system formed by addition of an excess of either m-monosulfonated triphenylphos-phine (TPPMS) or trisulfonated triphenylphosphine (TPPTS) to various Ru(II) precursors [2 a], It is believed that the catalytically active species is a mononuclear Ru(II) complex with chloride and hydride ligands. 

The details and the backgroimd of RCH/RP s developments have been described elsewhere. The work of Kuntz (then at RP see Section 2.4.1.1.1) on trisulfonated triphenylphosphine (TPPTS) and the industrial implementation and improvements developed by Ruhrchemie eventually laid the foundation for the subsequent successful commercialization [3]. TPPTS is the ideal ligand modifier for the oxo-active HRh(CO)4. Without any expensive preformation steps, three of the four CO ligands can be substituted by the readily soluble (1100 g L water) and nontoxic (LD50, oral > 5000 mg kg ) TPPTS, which yields the hydrophilic 0x0 catalyst HRh(CO)[P(3-sulfophenyl-Na)3]3. The trisulfonation, in particular, permits the fine adjustment ofTPPTS and thus of the hydrophilic versus the hydrophobic properties hydrophilicity is ranked in the order TPP3 S > TPPDS > TPPMS, from the trisulfonated through to the monosulfonated species. 

Commercially, the aqueous-phase concept was firstly applied in Ruhrchemie/Rhone-Poulenc s (RCH/RP) process (for the fundamentals, see Section 2.4.1.1). In several units the RCH/RP process has been converting propene to n-butyraldehyde and isobutyraldehyde (or butenes to valeraldehydes) since 1984 in the presence of HRh(CO)(TPPTS)3 (with TPPTS = m-trisulfonated triphenylphosphine or tris-(sodium-fn-sulfonatophenyl)phosphine as water-soluble ligand) according to Eq. (1). The output of the units mentioned is approximately890 000 tpy, which corresponds to roughly 13% of the world s total production. 

Figure 19 Hydroformylation with water-soluble ligands in aqueous media. TPPTS=trisulfonated triphenylphosphine.

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