Arylphosphines, sulfonated

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... 

Bohnen et report a hydroformylation method to convert olefins or olefinically unsaturated compounds in the presence of at least one rhodium compound and sulfonated arylphosphines in ILs based on a quaternary ammonium ion or the equivalent of a multiply charged ammonium ion and organic sulfonates or sulfates. 

Solubility of the catalysts in water can be due either to their overall charge or to their water-soluble ligands. Most frequently, derivatives of well-known tertiary phosphines (modified by sulfonation, carboxylation, phosphonation, etc.) serve as such ligands (structures 1-16). Among these, sulfonated arylphosphines are easily available, stable and well soluble in water over a wide pH range. 

Several representatives of the widely studied tertiary phosphine ligands for enantioselective hydrogenation in aqueous solutions are shown as Structures 21 -39. It is seen that the most successful ligands in this field do have their water-soluble, mostly sulfonated, derivatives [7, 11]. In case of acid-sensitive compounds, solubility in water could be achieved by attaching dimethylamino substituents to the parent arylphosphines and by their further protonation or quaternization. Monophosphines, such as 21 [88], played a minor role in comparison with the chelating diphosphines. Water-soluble phosphine-phosphinite ligands (L) were obtained from trehalose and used as components of with [Rh(cod)(L)[BF4]] catalysts for the enantioselective hydrogenation ofenamides [157]. 

Several interesting variations on the reaction have recently been introduced. While the reaction with water is often carried out using a sulfonated, and hence water-soluble, tri-arylphosphine, the use of a palladium(O) complex of l,3,5-triaza-7-phosphaadamantane (77, Scheme 25) was recently reported. Monflier and co-workers reported that in addition to running the reaction under a CO2 atmosphere, the reaction of butadiene with water is facilitated by the use of cationic or neutral (nonionic) surfactants. The role of cationic surfactants such as dodecylammonium hydroxide is conceived to be threefold ... 

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