TPPMS systems

Similarly, it remained an isolated example that [Pd(OAc)2]/TPPMS systems yielded 1,2-propyleneglycol when heated in aqueous allyl-alcohol... 

The spectrometer supports phase cycling, asynchronous sequence implementation, and parameter-array experiments. Thus, most standard solid-state NMR experiments are feasible, including CPMAS, multiple-pulse H decoupling such as TPPM, 2D experiments, multiple-quantum NMR, and so on. In addition, the focus of development is on its extension of, or modification to, the hardware and/or the software, in the spirit of enabling the users to put their own new ideas into practice. In this paper, several examples of such have been described. They include the compact NMR and MRI systems, active compensation of RF pulse transients, implementation of a network analyzer, dynamic receiver-gain increment,31 and so on. 

The use of water-soluble ligands was referred to previously for both ruthenium and rhodium complexes. As in the case of ruthenium complexes, the use of an aqueous biphasic system leads to a clear enhancement of selectivity towards the unsaturated alcohol [34]. Among the series of systems tested, the most convenient catalysts were obtained from mixtures of OsCl3 3H20 with TPPMS (or better still TPPTS) as they are easily prepared and provide reasonable activities and modest selectivities. As with their ruthenium and rhodium analogues, the main advantage is the ease of catalyst recycling with no loss of activity or selectivity. However, the ruthenium-based catalysts are far superior. 

The use of water-soluble metal catalysts for the hydrogenation of thiophenes in aqueous biphasic systems has been primarily introduced by Sanchez-Delgado and coworkers at INTEVEP S.A. [61]. The precursors RuHC1(TPPTS)2(L2) (TPPTS=triphenylphosphine trisulfonate L=aniline, 1,2,3,4-tetrahydroquinoline) and RuHC1(TPPMS)2(L2) (TPPMS=triphenylphosphine monosulfonate) were... 

Key to figure Species frequency/ durst ion System NOAEL (ppm) Less serious tppm) Serious [Pg.204]

A ligand with great potential for hydroformylation of higher, terminal alkenes is monosulfonated triphenylphosphine, tppms, that was studied by Abatjoglou, also at Union Carbide [12] (section 8.2.6). In this system hydroformylation is carried out in one phase that is worked up afterwards by adding water, which gives two phases to separate catalyst and product. 

Catalysis experiments were performed to investigate the telomerization of butadiene with ethylene glycol in selected TMS systems (e.g. si toluene DMF 1 5 4 or sl 2-octanol DMSO 1.35 3 5.2). With Pd/TPPTS as the catalyst a maximum yield of only 10% of the desired products could be achieved. With Pd/TPPMS the yield increased up to 43% in the TMS system si toluene isopropyl alcohol, but additional water had to be added to obtain a phase split after the reaction. The catalyst leaching is very high and 29% of the palladium used is lost to the product phase. 

As a polar solvent for the catalyst ethylene carbonate (EC), propylene carbonate (PC) and acetonitrile were used. Tricyclohexylphosphine, triphenyl-phosphine and the monosulfonated triphenylphosphine (TPPMS) were investigated as ligands with Pd(acac)2 as the precursor. Cyclohexane, dodecane, p-xylene and alcohols (1-octanol, 2-octanol and 1-dodecanol) were tested as non-polar solvents for the product. To determine the distribution of the product and of the catalyst, the palladium precursor and the hgand were dissolved in the polar solvent and twice as much of the non-polar solvent was added. After the addition of 5-lactone, the amounts of the product in both phases was determined by gas chromatography. The product is not soluble in cyclohexane and dodecane, more than 99% of it can be found in the polar catalyst phase. With the alcohols 1-octanol, 2-octanol and dodecanol about 50 to 60% of the 5-lactone are located in the non-polar phase. With p-xylene biphasic systems can only be achieved when EC is used as the polar solvent and even in this solvent system one homogeneous phase is formed at a temperature higher than 70 °C. In a 1 1 mixture of EC and p-xylene about 50 to 60% of the product is contained in the polar phase. 

W(CH3CN)(C0)3(TPPMS)2] was obtained in the reaction of TPPMS and [W(CH3CN)3(C0)3], and was used as catalyst in hydrogenation of benzene in water/heptane biphasic systems [164]. At 100 °C and 70 bar H2 the catalytic activity was found rather low (average TOP 1 h ). The same complex is also active in the hydrogenation of olefins (e.g. 1-hexene, 2,3-dimethyl- 1 -butene). 

Cyanation of iodoarenes with NaCN was catalyzed by [PdCl2(TPPMS)2] in the presence ofNaBH4 and ZnC in water/heptane, toluene or anisole biphasic systems (Scheme 9.11) [37]. Lipophilic catalysts prepared with P(p-tolyl)3 or PPhs showed negligible activities for the biphasic cyanation, due to the lack of CN in the organic phase. The reaction provided good to excellent yields of the respective benzonitriles with several substituted iodoarenes. 

In a water/chlorobenzene biphasic system, reduction of aromatic aldehydes by hydrogen transfer from aqueous sodium formate catalyzed by [ RuCl2(TPPMS)2 2] provided unsaturated alcohols exclusively (Scheme 10.7). Addition of 3-CD shghtly inhibited the reaction [13]. It was speculated that this inhibition was probably due to complexation of the catalyst by inclusion of one of the non-sulfonated phenyl rings of the TPPMS ligand, however, no evidence was offered. 

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 role of the surfactants has been evaluated with other hydrosoluble catalysts. It was found that the activity of the system depends on the surfactant/ligand parr, the highest conversion being achieved with CTAB/TPPMS couple (Conv. = 80% 3% corresponding to a DS = 0.105 0.005) [55]. 

Water soluble Rh/tppts and Rh/tppms complexes dissolved in nonaqueous media such as the ionic liquids, l-ethyl-3-methylimidazolium or l-n-butyl-3-methylimidazolium salt have also been used as catalysts in the hydroformylation of 1-pentene employing a two phase system.15,16 The yields obtained were 16-33% (TOF=59-103 h 1) without any leaching of the rhodium from the ionic liquid to the aldehydes/feedstock phase. Rh/PPh3 catalysts exhibited higher rates (TOF=333 h 1) for the same biphasic reaction albeit with leaching of rhodium due to the uncharged nature of the catalytic system.15... 

Virtually quantitative conversions were observed in the hydroformylation of 1-tetradecene with rhodium complexes generated from the lithium salt of tppms or the lithium (sodium) salts of 21 (Table 2 R=Ph n=3,4) and 22 (Table 2) in methanol as solvent.127,334 Catalyst recycling involved evaporation of methanol and addition of water to form a two phase system, separation of the aqueous phase, evaporation to dryness and addition of MeOH. 

Hydrogenation of r/wu-cinnamaldehyde (Figure 14 I Ri=H, R2=Ph) to phenylpropanol (IV Ri=H, R2=Ph) catalysed by Ru/tppms and Ru/tppts proceeds via two different routes in an aqueous/organic two phase system.492 With HRuCl(CO)(tppms)3 the reaction proceeds exclusively via the hydro-cinnamaldehyde III whereas with HRuCl(CO)(tppts)3 both II and III are involved (Figure 14, Ri=H, R2=Ph) 492... 

Osmium complexes modified with tppts and tppms also catalyse the selective hydrogenation of cinnamaldehyde to cinnamylalcohol (Figure 14, II) in an aqueous/organic two phase system.493 The selectivity towards the unsaturated alcohol II with Os/tppts was lower than with Ru/tppts but both Ru and Os/tppts... 

Telomerization is one of the very first reactions carried out in aqueous/organic two phase systems. In 1976, Kuntz at Rhone-Poulenc518 reduced PdCl2 with NaBH4 in the presence of tppms to afford a catalyst for the telomerization of... 

Na-salt n=0, R=H, Li-salt) catalysts524 (the latter was used in polar solvents such as ethanol and sulfolane) or of terminal alkynes catalysed by Rh/tppms and Rh/42 (Table 3 n=2) systems.525... 

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