Solution pH: A Selectivity Switch in Aqueous Organometallic Catalysis—Hydrogenation of Unsaturated Aldehydes Catalyzed by Sulfonatophenylphosphane–Ru Complexes

A pyridyl-triazole ligand for ruthenium and iridium catalyzed CC and CO hydrogenations in water/organic solvent biphasic systems

“…the unsaturated alcohol selectively forms. Nevertheless, exceptions are known [37], and, in particular, it is to remind that Joó [38] demonstrated that the pH of the aquous phase may strongly influence the hydrogenation selectivity.…”

“…Summing up, complex 2 appears endowed with an interesting catalytic activity which does not appear to be far from that of the most employed biphasic hydrogenation catalysts based on sulphonated mono-and diphosphines [38,39] and compares favourably with that of water soluble nitrogen ligands [37b]. To further explore the scope of our ligand in aqueous biphasic hydrogenation, we studied the catalytic activity of a system prepared by combining in situ Na1 with [Ir( 4 -COD)Cl] 2 (COD: 1,5-cyclooctadiene) which is a commercially available iridium precursor widely used in hydrogenation reactions [40,41].…”

Ionic liquids as acid/base buffers in non-aqueous solvents for homogeneous catalysis: A case of selective hydrogenation of olefins and unsaturated aldehyde catalyzed by ruthenium complexes

“…It is well-known that many chemical reactions are pH-related, that is, the outcome and even the nature of the products may be altered appreciably if the pH changes significantly during the process of reaction [1][2][3][4][5][6][7][8][9][10]. This is especially true in biochemical reactions where the pH is important to the proper metabolism and functioning of animals and plants [11,12].…”

“…Also, accumulated examples of pH-dependent selective hydrogenation catalyzed by transition-metal complexes in aqueous media have been reported by several groups. The ability to vary the activity and selectivity of a water-soluble catalyst by modulating pH became one of the unique aspects of aqueous-phase catalysis [1][2][3][4][5][6][7]. Some of them showed valuable catalytic performance in aqueous solutions or aqueous/organic biphasic systems.…”

“…The present study extends the facile synthesis of a series of IL-buffers and demonstrates their acid/base controllability in connection to the formations of rutheniumhydride complexes in non-aqueous media. We choose the selective hydrogenation of olefins and trans-cinnamaldehyde (CAL), as a probe reaction for the purpose of elucidating the relationship between the ruthenium species and their catalytic performances in IL-buffered non-aqueous solvents by the means of 1 3 ] were synthesized by the known procedure and identified by their NMR spectra [38][39][40].…”