Making bonds all over again

Recycling catalysts brings new dimension to carbon-carbon bond formation

Chemists are rising to the challenge to become more environmentally responsible, as researchers in the UK and Spain are proving with their palladium (Pd) catalysts research.

Pd catalysts have arguably revolutionised synthetic chemistry and crop up everywhere, particularly for making carbon-carbon bonds, a process at the core of natural product synthesis, pharmaceutical chemistry and conjugated materials for the electronics industry.

The trouble is often these catalytic reactions need a lot of heat and time to work, and the catalyst is often destroyed in the process.

Ian Fairlamb, at the University of York, and his colleagues in Murcia and Cartagena, have looked long and hard at the ligands best placed to enhance catalytic activity in a group of Pd catalysts and have come up with a system that is air stable, able to withstand heat, and most importantly, reuseable. The systems contain the nitrogen-based imidate group and form cyclic Pd complexes.

Fairlamb’s motivation is wide ranging: ’Our research was motivated by a desire to improve reaction efficiency.We also sought to develop an environmentally benign process’.

Todd Marder, from Durham University, UK, also researching new catalytic systems, explains the relevance of Fairlamb’s work: ’the popularity of these C-C bond-forming reactions has grown at an enormous pace over the past few years, with applications from pharmaceutical synthesis to new optoelectronic materials. This work provides new catalysts systems which exhibit good activity and stability and can be recycled’.

Fairlamb concedes that there is still much to be done to understand fully his catalytic systems, saying that there is an ’urgent need to develop in situ tools to probe the reaction dynamics and to assist in identifying the key active Pd species’. He adds: ’Another challenge is to extend these reactions to less reactive starting materials and thereby broaden the scope of potential products.’

Katharine Sanderson