Phosphines BISBIS

Both of the most famous tran -chelating phosphines, BISBI [12] and the similar 2,2 -bis(diphenylphosphinomethyl)-l-T-binaphthalene [13], can be sulfonated ... 

Much progress has been made on regioselective hydroformylation of terminal alkenes in favor of the linear product. In particular bidentate phosphine or phosphite ligands, which have a natural bite angle 9 of about 110°, will favor the linear product. The most successful ligand types are BISBI [49, 50], BIPHEPHOS [51,52], and XANTPHOS systems (Scheme 8) [53]. 

More recent advances in iridium-catalyzed aldehyde hydrogenation have been through the use of bidentate ligands [6]. In the hydrogenation of citral and cinnamaldehyde, replacing two triphenylphosphines in [IrH(CO)(PPh3)3] with bidentate phosphines BDNA, BDPX, BPPB, BISBI and PCP (Fig. 15.1) led to an increase in catalytic activity. 

Figure 11.6 Effect of varying the water soluble phosphine ligand on the hydroformylation of propene to butyraldehyde. P Rh ratio = TPPTS 80 BISBIS 7 NORBOS 14 BINAS 7...

Using RuCl(CO)(TPPTS)(BISBIS) the biphasic aqueous hydroformylation of higher olefins in the presence of the cationic surfactant CTAB ensures a TOF > 700 h and regioselectivity >96% for the linear aldehyde Piperazinium cationic surfactants were also successfully applied as catalysis promotion agents in the aq. biphasic hydroformylation of higher olefins. The property of surfactant and ligand can be assumed by the same molecule, e.g. di-sulfonated cetyl(diphenyl)phosphine 42. 1-Dodecene is hydroformylated in water/toluene (3 1) under mild conditions [olefin/Ru = 2500, CO/H2=1, P(CO + H2) = 15 bar, 42/Ru = 10] with TOF = 188 Another approach to... 

Another approach to water-soluble phosphines with the emphasis on metal recycling was reported by van Leeuwen and co-workers [30], They have synthesized a number of diphosphines that, when coordinated to rhodium, form complexes having an amphiphilic character. The ligands synthesized are based on BISBI and Structures 20-22, and hydroformylation (for example) can be conducted in a homogeneous (organic) phase [30 a]. After it has been used in the hydroformylation of olefins the catalyst can be removed by acidic extraction. It was established that these novel diphosphines form active and highly selective catalysts. This amphiphilic approach, i.e., rhodium recycling abased on the extraction and re-extraction principle, will be discussed in more detail in Section 7.5. 

Other Water-soluble Phosphines BINAS and BISBIS... 

Many cataly.st systems with phosphine and phosphite ligands have been developed to enhance the linear selectivity of the reaction. 2-219 example, rhodium complexes of BISBI (24) (linear/branched >... 

Chiral phosphines can be made water soluble by using similar approaches and the two most important chiral diphosphines are sulfonated 2,2 -bis-(diphenylphosphinomethyl)-l,l -binaphthyl (BINAS)-8 15 and the BISBIS 16 (Figure 9). The preparation of these types of ligands involves sulfonation with fuming sulfuric acid, similarly to the other phosphines. The position of the sulfonate groups depends on the temperature and the SO3 concentration. The oxidation of the product can be hindered by the preparation of superacidic media from orthoboric acid and anhydrous sulfuric acid. ... 

But all the monometallic catalysts deactivate before they can complete the 1,000 turnovers (100% conversion of alkene). This is tied into Rh-induced phosphine orthometalations and P-Ph or P-benzyl bond cleavage reactions that lead to monometallic catalyst deactivation [4], Bisbi is especially susceptible to deactivation under these conditions, barely making it past 50% conversion of the alkene. The mainly alkylated et,ph-P4 ligand does not seem to suffer from Rh-induced phosphine fragmentations under these conditions, but does tend to lose a rhodium center and fragment losing the bimetallic cooperativity. 

Several new water-soluble phosphines were prepared for hydroformylation catalyzed by rhodium(I) complexes. These include the sulfonated derivatives BISBIS (16), BINAS (16,139), BIPHLOPHOS (143), sulfonated XANTPHOS (144), and others (Scheme 15). Rh-BINAS showed an enormously high activity in propene hydroformylation at 125°C and 5.2 MPa syngas, TOF = 10710 h , which was about 12 times higher than that of Rh-TPPTS under the same conditions (143). At the same time, the selectivity also increased to n/iso 98/2 from 95/5. Despite these improvements, the low price and availability still favors the industrial use of [HRh(CO)(TPPTS)3] -I- excess TPPTS. 

Besides the TPPTS-system a number of other sulfonated phosphine ligand systems were investigated and tested on a pilot plant scale. Among them are systems which are derived from biphenyl (BISBIS = sulfonated bis(diphenylphosphinomethyl)biphenyl, varying grades of snlfonation of... 

Among other sulfonated chelating phosphines are ligands BISBIS, BINAS, and highly hydrophihc exhaustively sulfonated BlNAS-b (Scheme 9). 

The binaphthyl analog of BISBI is called NAPHOS (Scheme 2.17). A common access suggested by a Hoechst group is an adaptation of the BISBI synthesis of Eastman Kodak [54]. 2,2 -DimethyI-I,I -dinaphthyI, which is employed as starting material, can be produced either by Grignard reaction or by Pd-catalyzed aryl—aryl coupling. The incorporation of the phosphine groups... 

The results with monodentate phosphines led to the idea of using a bidentate phosphine ligand, such as Xantphos, DIOP, or BISBI, together with PEtj [71]. Under these conditions, higher olefins such as 1-hexene, 1-octene, or 1-decene,... 

Alternatively, the group of Nozaki used alkyl derivatives of BISBI for the hydroformylation-reduction of 1-decene (Scheme 5.55) [73]. Large P-alkyl substituents lowered the yield of the alcohol. The authors assumed therefore that steric effects of the phosphine are more dominant than electronic effects. Also, in these attempts the alcohols as a solvent proved to be essential. In some cases, the formation of aldol products inhibited the formation of the desired alcohols. 

In Rh-catalyzed hydroformylation, the n iso ratio increases with the bite angle = (preferred P-M-P angle) of a chelate phosphine, probably because these ligands facilitate the RE step in the mechanism. The Rh complex (9.27) of the wide bite angle ligand, BISBI, has proved particularly useful. ... 

---