Tris-sulfonated triphenylphosphine

Water-soluble phosphine ligands TPPMS, TPPDS, and TPPTS (mono-, di-, and tri-sulfonated triphenylphosphine, respectively) were tested as ligands for the hydration of aUcynes in aqueous media [116]. Complexes 19 and 20 (Fig. 1) gave the highest turnover frequencies ever reported (1,000 and 1,060 h , respectively) for the hydration of phenylacetylene under optimum conditions (0.1 mol% catalyst loading, 10 mol% H2SO4, reflux, and MeOH/H20). 

With the knowledge that 14 can activate aldehydes in 1, the role of 1 in the reaction was explored further. Specifically, the relative rates of C—H bond activation and guest ejection, and the possibility of ion association with 1, were investigated. The hydrophobic nature of 14 could allow for ion association on the exterior of 1, which would be both cn t h al pi cal I y favorable due to the cation-it interaction, and entropically favorable due to the partial desolvation of 14. To explore these questions, 14 was irreversibly trapped in solution by a large phosphine, which coordinates to the iridium complex and thereby inhibits encapsulation. Two different trapping phosphines were used. The first, triphenylphosphine tris-sulfonate sodium salt (TPPTS), is a trianionic water-soluble phosphine and should not be able to approach the highly anionic 1, thereby only trapping the iridium complex that has diffused away from 1. The second phosphine, l,3,5-triaza-7-phosphaadamantane (PTA), is a water-soluble neutral phosphine that should be able to intercept an ion-associated iridium complex. 

The latest development in industrial alkene hydroformylation is the introduction by Rurhchemie of water-soluble sulfonated triphenylphosphine ligands.94 Hydroformylation is carried out in an aqueous biphasic system in the presence of Rh(I) and the trisodium salt of tris(m-sulfophenyl)phosphine (TPPTN). High butyraldehyde selectivity (95%) and simple product separation make this process more economical than previous technologies. 

Cuprous chloride tends to form water-soluble complexes with lower olefins and acts as an IPTC catalyst, e.g., in the two-phase hydrolysis of alkyl chlorides to alcohols with sodium carboxylate solution [10,151] and in the Prins reactions between 1-alkenes and aqueous formaldehyde in the presence of HCl to form 1,3-glycols [10]. Similarly, water-soluble rhodium-based catalysts (4-diphenylphosphinobenzoic acid and tri-Cs-io-alkylmethylam-monium chlorides) were used as IPTC catalysts for the hydroformylation of hexene, dodecene, and hexadecene to produce aldehydes for the fine chemicals market [152]. Palladium diphenyl(potassium sulfonatobenzyl)phosphine and its oxide complexes catalyzed the IPTC dehalogenation reactions of allyl and benzyl halides [153]. Allylic substrates such as cinnamyl ethyl carbonate and nucleophiles such as ethyl acetoactate and acetyl acetone catalyzed by a water-soluble bis(dibenzylideneacetone)palladium or palladium complex of sulfonated triphenylphosphine gave regio- and stereo-specific alkylation products in quantitative yields [154]. Ito et al. used a self-assembled nanocage as an IPTC catalyst for the Wacker oxidation of styrene catalyzed by (en)Pd(N03) [155]. 

Sulfonated triphenylphosphine [TPPTS (triphenylphosphine, m-trisulfonated) tri(m-sulfophenyl)phosphine] (II-l) and monosulfonated triphenylphosphine [TP-PMS (triphenylphosphine, monosulfonated) 3-(diphenylphosphino)benzenesul-fonic acid] (II-2) are commercially available ligands and their sodium salts are water-soluble [15]. The Na salt of the ligand TPPTS is very soluble and may be too soluble in water, hence moderately soluble TPPMS is preferred. Another water-soluble phosphine is 2-(diphenylphosphinoethyl)trimethyl ammonium halide (II-11) [16]. A number of other water-soluble phosphines are now known (Table 1.2). Pd complexes, coordinated by these phosphines, are soluble in water, and Pd-catalyzed reactions can be carried out in water, which is said to have an accelerating effect in some catalytic reactions. 

A 7i-allyl species like allylic acetates, carbonates, and carbamates are inert towards amino acid functionalities until they are activated with a palladium catalyst like palladium acetate and triphenylphosphine tris(sulfonate) as a water-soluble ligand [138, 139]. With a palladium catalyst, the phenolate oxygen of tyrosine will be alkylated. The conjugate is an aUyl aryl ether (14) (Table 4). 

Much research has been devoted to water-soluble sulfonated phosphines and, in particular, the well-known TPPTS (triphenylphosphine tris-sulfonated sodium salt) ligand used in propene hydroformylation on an industrial scale by Ruhrchemie/ Rhone-Poulenc since 1982 (Figure 6.8) [9, 10]. 

Replacement of tppts by the fluoro substituted sulfonated ligand 4 [Table 2 94% (n=l) and 6% (n=0)] in the rhodium-catalysed hydroformylation of 1-hexene in a two phase system increased the selectivity to linear aldehyde n-heptanal from 86% to 93% at the low P/Rh molar ratio of 7.5/1.75,76 The Rh/4 catalyst was quantitatively recovered after the reaction by simple decantation.75,76 The moderate increase of the n/i ratio is of interest when one considers that ligand 4 is mainly present as the disulfonated species (94%) compared to the trisulfonated compound tppts and that tris(4-fluorophenyl)phosphine is less basic (pKa=1.97) than triphenylphosphine (pKa=2.73).376 In rhodium-catalysed hydroformylation reactions in organic solvents it is known that electron withdrawing substituents, which increase the -acidity of the ligand, give rise to an increase in the n/i ratio.377 379... 

LACTAMS Di-n-butyltin oxide. Ily-droxylamine-O-sulfonic acid. Iodine azide. Sodium eyanoborohydride. (3-LAC TAMS Cyanuric chloride. Grignard reagents. Ion-exchange resins. Lithium phenylethynolate. Sodium dicarbonyl-cyclopentadienylferrate. Titanium(lll) chloride. Titanium(IV) chloride. Tri-phenylphosphino-Carbon tetrachloride. Triphenylphosphine-Die thyl azodicar-boxylate. Triphenylphosphine-2,2 -Dipyridyl disulfide. 

Kuntz subsequently showed that the RhCl (tppts) 3 catalyzed the hydroformylation of propylene in an aqueous biphasic system [29]. These results were further developed, in collaboration with Ruhrchemie, to become what is known as the Ruhrchemie/Rhone-Poulenc two-phase process for the hydroformylation of propylene to n-butanal [18, 19, 22, 30]. Ruhrchemie developed a method for the large scale production of tppts by sulfonation of triphenylphosphine with 30% oleum at 20 °C for 24 h. The product is obtained in 95% purity by dilution with water, extraction with a water insoluble amine, such as tri(isooctylamine), and pH-controlled re-extraction of the sodium salt of tppts into water with a 5% aqueous solution of NaOH. The first commercial plant came on stream in 1984, with a capacity of 100000 tons per annum of butanal. Today the capacity is ca. 400000 tpa and a cumulative production of millions of tons. Typical reaction conditions are T=120°C, P=50bar, CO/H2 = 1.01, tppts/Rh = 50-100, [Rh] = 10-1000 ppm. The RhH(CO) (tppts)3 catalyst is prepared in situ from e.g. rhodium 2-ethylhexanoate and tppts in water. 

The water-soluble ligand used by Kuntz and Comils is TPPTS [tri(m-sulfonyl)triphenylphosphine trisodium salt], the properties of which are veiy similar to the parent compound tpp. Sulfonation of triphenylphosphine, neutralization, followed by pH-controUed selective extraction and reextraction procedures, yieltk an aqueous solution of the trisodium salt of tris(m-sulfonyl)triphenylphosphine in good yields. The catalyst used is a... 

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