Phosphines-Bearing Functional Groups

The incorporation of functional groups into the phosphine alters the solubility properties of the hgand and, consequently, those of the hydroformylation catalyst. Especially, sulfonate, carboxylate, or phosphonate groups enhance the solubihty of the catalyst in polar solvents (see Section 7.3.2). Ammonium groups can be used to construct ionic interactions with special negatively charged counter-ions. 

Li s group synthesized DMOPPS by reacting concentrated H2SO4 with the relevant phosphine diether (DMOPP) [92]. The ligand combines polar sulfonate 

A similar approach was followed by Monflier and coworkers [94], who sulfonated biphenyl phosphines and screened the resulting BiphTS ligands in the cobalt-catalyzed aqueous biphasic hydroformylation. These phosphines have a solubihty in water of 1.0kgl . Compared to TPPTS, BiphTS ligands are more basic. Remarkably, PfBiPhljTS possesses a basicity similar to that of PPhj, which means that the deactivating effect of the sulfonate groups is fully suspended. 

In general, such trialkyl phosphines do not undergo degradation by P - aryl bond cleavage during rhodium-catalyzed hydroformylation (see Section Cleavage of P-Aryl Bonds ) [96]. 

Unfortunately, to date only TPPTS is available in quantities useful for scale-up purposes, which may be explained by the rather unpleasant synthetic protocol required. The hydroformylation with TPPTS is the only aqueous two-phase hydroformylation used in industry to date [98]. Up to now, the use of BINAS and related sulfonated diphosphines is limited to academic hydroformylation studies [85, 99,100]. 

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Bifunctional linkers bearing functional groups like thiols, disulfides or phosphines are widely used for covalent binding between Au NPs and biomolecules. For example, Au NPs stabilized with a functionalized polysiloxane shell have been used for covalent binding to biomolecules [152]. 

Functionally substituted phosphines play an important role as ligands in a great variety of phosphorus coordination compounds. They have some interesting features that distinguish them from other phosphine ligands, namely (a) the presence of other heteroatoms bearing lone electron pairs in addition to phosphorus (b) the presence of functional groups able to form bonds with a metal with the participation of its valence electrons ... 

The A3-phospholen sulphides (44), bearing reactive functional groups, may be reduced to the phosphine using nickelocene in the presence of allyl iodide.37 The intermediate nickel complex is decomposed with cyanide to free the functionalized A3-phospholen (45). 

Although thiol ligands are the most widely used as stabilizers in the synthesis of Au NPs, other organic ligands bearing amine, phosphine, phosphine oxide, carboxylate or other functional groups have been employed alone or in mixtures. 

According to route A, functionalized organosilanes, derived from a commercially available precursor [68], are first reacted with a suitable metal compound, e. g., a rhodium cyclooctadiene complex, resulting in the formation of a monomeric metal-phosphine complex bearing alkoxysilyl groups. Subsequently in a... 

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