Glycerol - A Non-Innocent Solvent for Rh-Catalysed Pauson-Khand Carbocyclisations

Glycerol Boosted Rh-Catalyzed Hydroaminomethylation Reaction: A Mechanistic Insight

We report a Rh-catalyzed hydroaminomethylation reaction of terminal alkenes in glycerol that proceeds efficiently under mild conditions to produce the corresponding amines in relatively high selectivity towards linear amines, moderate to excellent yields by using a low catalyst loading (1 mol % [Rh], 2 mol % phosphine) and relative low pressure (H₂ /CO, 1:1, total pressure 10 bar). This work sheds light on the importance of glycerol in enabling enamine reduction via hydrogen transfer. Moreover, evidence for the crucial role of Rh as chemoselective catalyst in the condensation step has been obtained for the first time in the frame of the hydroaminomethylation reaction by precluding deleterious aldol condensation reactions. The hydroaminomethylation proceeds under a molecular regime; the outcome of catalytically active species into metal-based nanoparticles renders the catalytic system inactive.

Catalysis in glycerol: a survey of recent advances

There is currently a significant increase in the use of glycerol as a renewable solvent for catalytic reactions. Glycerol has often been the solvent of choice in both homogeneous and heterogeneous catalyses, despite its high viscosity at ambient temperature and the low solubility of highly hydrophobic reagents found in glycerol. Its biodegradability and non-toxicity have led to reports of improved reaction performance and selectivity, as well as easier product separation and effective catalyst recycling. All relevant advances in this emerging field of “green” catalysis are thoroughly reviewed below.

Glycerol as suitable solvent for the synthesis of metallic species and catalysis

This Minireview considers the foremost reported works involving glycerol as a solvent in the synthesis of organometallic complexes and metallic nanoparticles. This analysis highlights their catalytic applications. A special emphasis is devoted to the ability of glycerol to immobilize nanometric species, which, in turn, enables an efficient recycling of the catalytic phase to give metal-free organic products.