Direct synthesis of hydrazine by efficient electrochemical ruthenium-catalysed ammonia oxidation

A century after hydrazine was discovered, its synthesis remains a challenge due to its high energy requirement and favourable subsequent conversion. As an alternative to the traditional industrial processes, the direct electrochemical oxidation of ammonia is an ideal reaction for hydrazine synthesis. However, suitable methods still need to be developed. Here we show that ruthenium complexes bearing 2-[5-(pyridin-2-yl)-1H-pyrrol-2-yl]pyridine ligands display high catalytic activity for the direct electrochemical oxidation of ammonia to generate hydrazine in acetonitrile. Our developed CSU-2 complex reached a turnover number for hydrazine formation of 5,735 within 24 h at an applied potential of 1.0 V versus Cp2Fe+/0. The results reveal a bimolecular N-N coupling mechanism involving RuII-aminyl or RuIII-iminyl intermediates. The electrochemical synthesis of hydrazine is a very attractive yet challenging process. Now, the direct electrochemical oxidation of ammonia to hydrazine on a Ru complex catalyst, involving a bimolecular N-N coupling mechanism, is reported.

Automated summary

The direct electrochemical oxidation of ammonia to hydrazine is an attractive yet challenging process. Researchers reported a method using a Ru complex catalyst and involving a bimolecular N-N coupling mechanism.