Homogenous catalytic hydrogenation of bicarbonate with water soluble aryl phosphine ligands

Synthesis of Hydrophilic Phosphorus Ligands and Their Application in Aqueous-Phase Metal-Catalyzed Reactions

Transition metal-catalyzed reactions in aqueous media are experiencing a constant increase in interest. In homogenous catalysis the use of water as a solvent offers advantages in cost, safety, the possibility of two-phase catalysis and simplified separation strategies. In the life sciences, transition metal catalysis in aqueous systems enables the ligation or modification of biopolymers in buffer systems or even in their cellular environment. In biocatalysis, aqueous systems allow the simultaneous use of enzymes and transition metal catalysts in cascade reactions. The use of water-soluble phosphine ligands still represents the most reliable and popular strategy for transferring metal catalysts into the aqueous phase. This review summarizes the recent advancements in this field since 2009 and describes current synthetic strategies for the preparation of hydrophilic phosphines and phosphites. In addition, recent applications of transition metal catalysis in aqueous solvents using these hydrophilic ligands are presented.

Sulfonated Phosphine Ligands in the Ruthenium Catalyzed Biphasic Hydrogenation of Unsaturated Hydrocarbons

Abstract

The hydrogenation of monocyclic aromatic hydrocarbons by ruthenium catalysts has been investigated in the presence of sulfonated monophosphine ligands with different stereoelectronic properties under biphasic conditions. The effects of (i) the number of sulfonate groups, (ii) the steric demand of the ligand and (iii) the σ-donor ability of the phosphorus atom have been investigated in the catalytic reactions. The TEM analysis of the catalytically active systems revealed that in situ formed soluble ruthenium nanoparticles (RuNPs) are responsible for the catalytic turnover. The Ru/sulfonated phosphine system with the properly tuned ligand exhibited high activity (8800 h−1) and selectivity in the hydrogenation of benzene to cyclohexane. Furthermore, the aqueous phase containing RuNPs could be recycled four times without a considerable loss of activity.

Graphic Abstract

Investigating the reactivity of neutral water-soluble Ru(ii)–PTA carbonyls towards the model imine ligands pyridine and 2,2′-bipyridine

The reactivity of selected Ru(ii)-PTA carbonyls with potentially labile ligands (i.e. H₂O, dmso and/or Cl) towards the model imine ligands pyridine and 2,2′-bipyridine was investigated, yielding several neutral and cationic water-soluble derivatives.