Selectivity Switch in the Aerobic 1,2‐Propandiol Oxidation Catalyzed by Diamine‐Stabilized Palladium Nanoparticles

Abstract

Palladium nanoparticles stabilized by a sterically demanding secondary diamine ligand have been synthesized by hydrogen reduction of a palladium acetate complex bearing the corresponding diimine ligand. The obtained nanoparticles were used to catalyze the aerobic oxidation of 1,2‐propandiol in n‐hexane, and after their heterogenization onto a high surface area carbon, in water. In n‐hexane (2,4‐dimethyl‐1,3‐dioxolan‐2‐yl) methanol has been obtained as major product, whereas in water acetic acid with a selectivity of >85 % has been achieved. The selectivity switch observed was a clear induced by water. The robustness of diamine‐stabilized palladium nanoparticles under real aerobic oxidation conditions has been proved by recycling experiments, TEM measurements of the recovered catalysts and by comparison of its performance with that of palladium nanoparticles generated by the metal vapor synthesis technique and supported onto the same carbon in the absence of the stabilizing diamine ligand.

Oxidation of Ethanol to Acetic Acid by Supported PtCu Nanoparticles Stabilized by a Diamine Ligand

“…31 Syntheses of Pt L , Cu L , and (PtCu) L . N,N′-Bis(hexadecyl)αdiimine 4 (400.0 mg, 0.79 mmol) reacted with PtCl 2 (211.0 mg, 0.79 mmol) or Cu(OAc) 2 (143.0 mg, 0.79 mmol) in deaereated CH 2 Cl 2 (20 mL) at room temperature for 3 h. Afterward, the obtained solutions were separately transferred into teflonated autoclaves (70 mL) by suction. The autoclaves were successively pressurized with hydrogen (20 bar), heated to 333 K, and magnetically stirred for 12 h. Afterward, the autoclaves were cooled to room temperature, the excess gas was vented off, and the obtained suspension was concentrated to dryness.…”

“…N,N′-Bis(hexadecyl)α-diimine was synthesized as reported previously. 4 EtOH, PtCl 2 , Cu(OAc) 2 , C 6 H 6 -d 6 , CHCl 3 -d, H 2 O-d 2 , and Nafion ion-exchange resin solution (5 wt %) were purchased from Aldrich and used without further purification. Dichloromethane was distilled over CaH 2 , and n-pentane was stored over molecular sieves.…”

“…An alternative hence synthesis protocol for AA might consist of the selective transformation of biomass-originating substrates by means of robust heterogeneous catalysts, using water as the solvent and oxygen (air) as the final oxidant. In this context, ethanol (EtOH), obtained from fermentation of biomass, is an attractive substrate, while 1,2-propandiol (1,2-PD), gained by hydrogenolysis of glycerol, − yields stoichiometric amounts of CO 2 by its conversion to AA …”

“…In this context, ethanol (EtOH), obtained from fermentation of biomass, is an attractive substrate, while 1,2-propandiol (1,2-PD), gained by hydrogenolysis of glycerol, 4−7 yields stoichiometric amounts of CO 2 by its conversion to AA. 4 The most efficient heterogeneous catalysts known for the aerobic EtOH-to-AA conversion are mainly Au-5−8 and Rubased. 9,10 Heterogeneous Pt-based catalysts have the advantage of being active in the absence of an extra base, thus avoiding the generation of huge amounts of inorganic salt.…”

Spectroscopic, DFT investigation and active site analysis of 2,2-diphenyl-1,3-propanediol against estrogen receptor EPR gamma

“…The demand for 1,3-Propanediol has been increasing rapidly on a global scale and has an annual market over 100 million pounds [4]. The production of 1,3-Propanediol was mainly for biological fermentation [5][6][7] or chemical synthesis [8][9][10][11].…”