Triphenylphosphine monosulfonic acid

The general flow scheme for this alternative is shown in Figure 15. After the homogeneous reaction, catalyzed for instance by a rhodium catalyst containing triphenylphosphine monosulfonic acid as complex ligand, the solubilizer methanol is distilled off. The catalyst system now becomes insoluble and is separated by extraction with water in the third unit. The products C and D, in this case the aldehydes, can be separated as the second liquid phase. After evaporation of the aqueous catalyst solution to dryness (unit 4) the catalyst is dissolved in the solvent methanol for a new reaction step (unit 5). 

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. 

Much emphasis has been placed in recent times on easily recoverable liquid bi-phasic catalysts, including metal clusters in nonconventional solvents. For instance, aqueous solutions of the complexes [Ru3(CO)12.x(TPPTS)x] (x=l, 2, 3 TPPTS = triphenylphosphine-trisulfonate, P(m-C6H4S03Na)3) catalyze the hydrogenation of simple alkenes (1-octene, cyclohexene, styrene) at 60°C and 60 bar H2 at TOF up to 500 h 1 [24], while [Ru i(CO)C (TPPMS) >,] (TPPMS = triphenylphos-phine-monosulfonate, PPh2(m-C6H4S03Na) is an efficient catalyst precursor for the aqueous hydrogenation of the C=C bond of acrylic acid (TOF 780 h 1 at 40 °C and 3 bar H2) and other activated alkenes [25]. The same catalysts proved to be poorly active in room temperature ionic liquids such as [bmim][BF4] (bmim= Tbutyl-3-methylimidazolium). No details about the active species involved are known at this point. 

With this last point in mind, the synthesis of mono-, bis- and tra-sulfonated triphenylphosphine will be described, but the same methodology can be applied to the preparation of other sulfonated arylphosphines. In general, these phosphines are made by direct sulfonation using fuming sulfuric acid (oleum) [21], The extent of sulfonation is determined by the SO3 strength, as well as factors such as the temperature and time of the reaction. The monosulfonated phosphine (tppms) is prepared using oleum of 20% SO3 strength, with typically 30% SO3 used... 

Fuming sulfuric acid (oleum) of 20% SO3 strength is suitable for preparation of monosulfonated products [1-3] while for multiple sulfonation 30% (or more) SO3 is required [4-10], The phosphine is dissolved in cold oleum with protonation of the phosphoms atom therefore in cases when the phenyl rings are directly attached to the phosphoms (e.g. triphenylphosphine or the bis(diphenylphosphino)alkanes) sulfonation takes place in the 3-position. 

The sulfonation of triphenyl phosphine with fuming sulfuric acid can give three possible products monosulfonated triphenylphosphine (TPPMS), disulfonated triphenylphosphine (TPPDS), and TPPTS 1, depending on the reaction conditions (Figure 9). Using this method many sulfonated aryl phophines have been prepared (2b,... 

The oxidation of monosulfonated triphenylphosphine with nitric oxide and nitrous acid was investigated in aqueous solution. The possible interconversion of phosphine chalcogenides was studied in the presence of Pd(0) catalyst. The reaction of a phosphine selenide with sulfur takes place via the phosphine that was separated as the Pd(II)complex. ... 

When investigating the aqueous-phase bicarbonate hydrogenation with ruthenium and rhodium complexes, Benyei and J06 observed certain activity for the reverse reaction, that is, formate decomposition. [RuCl2(mTPPMS)2]2 (mTPPMS = meta-monosulfonated triphenylphosphine) decomposed sodium formate and formic acid (41), while RhCl(mTPPMS)3 slowly decomposed calcium formate and promoted calcium carbonate precipitation (42). 

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