Amination Catalyst Boasts High Selectivity

Sept. 26, 2017
A reusable catalyst can produce primary amines from carbonyl compounds with negligible byproduct formation, report Japanese researchers.

A reusable catalyst can produce primary amines from carbonyl compounds with negligible byproduct formation, report Japanese researchers. The catalyst consists of ruthenium nanoparticles supported on niobium pentoxide (Figure 1).


Figure 1. Highly selective catalyst consists of ruthenium nanoparticles on niobium pentoxide support. Source: Tokyo Institute of Technology.

The catalyst enables efficient low-temperature reductive amination of carbonyl compounds having reduction-sensitive functional groups like heterocycles and halogens using ammonia and hydrogen as the nitrogen source and reductant, respectively, explain the researchers at the Tokyo Institute of Technology (Tokyo Tech), Yokohama. The superior catalytic efficiency — yields exceed 90% — stems from ruthenium’s weak electron-donating properties on the Nb2O5 support, they believe. More details appear in an article in the Journal of the American Chemical Society.

Michikazu Hara, a professor at Tokyo Tech’s Laboratory for Materials and Structures, and his coworkers then investigated the effectiveness of the catalyst for breaking down biomass (in the form of glucose) into 2,5-bis (aminomethyl)furan (AMF), a feedstock for aramid polymers. Teaming the catalyst with a so-called ruthenium-xantphos complex provided a 93% yield, with little or no byproduct formation observed. This success in producing AMF promises to spur the development of environmentally friendly aramid polymers, he believes. Moreover, the combination could enable efficient synthesis of other primary diamines from complicated hydroxyl- and carbonyl-groups containing compounds, the researchers note.

The approach also may suit other reactions, notes Hara. Many processes require reducing only the functional groups bonded to aromatic rings without the reduction of the aromatic rings, he explains, adding that he welcomes suggestions about reactions to explore. Success for them may hinge on addressing challenges in achieving a further decrease in electron donation and charge control.

Ultimately, the catalyst may foster development of pharmaceuticals, agrochemicals, biofuels and other products, the researchers hope.

Pilot plant trials might begin within five years, Hara believes. These would be conducted by an industrial partner, he notes, adding that several companies already have contacted the researchers.

Availability of the catalyst won’t be a barrier to commercial use, he says, because it can be mass produced by an established industrial method.

The researchers now are investigating the use of metals that are less expensive than ruthenium.