Hydrogenation of N-benzylideneaniline by palladium (II) catalysts with phosphorus-nitrogen ligands using formic acid as a renewable hydrogen source

Selective hydrogenation of furfural to furfuryl alcohol catalysed by ruthenium complexes containing phosphorus‐nitrogen ligands

“…Catalytic furfural hydrogenation is favoured by the presence of formic acid (substrate/formic acid = 2/1), which promotes the formation of active species for the hydrogenation reaction, [ 24 ] evidenced by the low conversion (29%) obtained when only molecular hydrogen was used. It was also found that the optimal substrate/acid ratio is around 2/1, since a major acid substrate/acid ratio (from 1/1 to 1/3) causes catalyst decomposition obtaining a dark brown precipitate in the reaction.…”

“…The N-P-N ligands and their corresponding ruthenium (II) complexes (Ru-1 and Ru-2, Figure 1) were synthesized following protocols reported by our group of investigators. [23,24] Catalytic essays were monitored by a GC analysis using a Perkin Elmer Clarus 580 GC chromatograph with a flame ionisation detector (FID) and equipped with an Elite-5 column. The product of the catalytic reaction was characterized using mass spectroscopy (GC-MS).…”

“…Our research group has successfully explored the hydrogenation of imines and other substrates using ruthenium and palladium complexes containing phosphorous-nitrogen ligands. [23,24] These ligands combine the coordinating properties of phosphorous and nitrogen (both with different affinities towards the central metal ion), thus providing highly stable catalysts in the processes of carbonylation and hydrogenation.…”

Catalytic Hydrogenation of Sorbic Acid using Pyrazolyl Palladium(II) and Nickel(II) Complexes as Precatalysts

“…Many phosphino nickel(II) and palladium(II) complexes are well-known catalysts for the hydrogenation of olefinic double bonds, 26-29 some of them featuring P ∧ N donor ligands. 29,30 These hydrogenation reactions were first carried out in the presence of a base, such as KOH, which facilitates the deprotonation of the formic acid to formate ion. The formate ion then coordinates to the metal centre leading to decomposition of the formic acid with the aid of the intermediate, [M]-OOCH as an active catalyst, to produce H 2 and CO 2 .…”

“…The formate ion then coordinates to the metal centre leading to decomposition of the formic acid with the aid of the intermediate, [M]-OOCH as an active catalyst, to produce H 2 and CO 2 . 29 This accelerates H 2 heterolysis and causes the catalytic process. 20(b), 30 A typical hydrogenation reaction was performed with sorbic acid and a complex present in a 200:1 mole ratio at 90 °C for 12 h (Fig.…”