It is this passion and concern that drives Dr Lipshutz to develop chemical reactions that are more environmentally friendly. He focuses on two areas: developing reactions that can be carried out in water, rather than in petroleum-based solvents; and developing catalysts that are effective even when used in very small quantities.
Many of the catalysts involved in organic synthetic reactions rely on heavy metals, which are not only rare and precious, but can contaminate the environment if they are not disposed of properly. It is therefore essential to reduce the quantity of these catalysts that we use in each reaction.
Most organic synthetic reactions take place in organic solvents, which are often toxic or flammable. Chemists use them because they readily dissolve most chemicals that are used in reactions, and it’s easy to remove them afterwards. But by designing reactions carefully, it is possible to carry them out in water. Most reactions in nature take place in a water-based medium, so chemists can examine these reactions for inspiration on how to do the same thing in a laboratory.
Dr Lipshutz and his team have developed a new catalyst for Sonagashira coupling reactions – an important reaction that can be used to build molecules for pharmaceuticals and agro chemicals, starting from commercially available precursors. The catalyst uses palladium, but on the part-per-million level – quantities an order of magnitude lower than previous catalysts. The catalyst avoids the use of copper – which is commonly used in Songashira coupling – and can carry out the reaction in water.
"In essence", says Dr Lipshutz, "we 'put the pieces together' in water, efficiently, with very little metal, and in an overall environmentally responsible manner."
"This work is representative of the overarching goal of transforming modern organic chemistry into a sustainable discipline, where the same phenomenal advances in this field being made on a regular basis can be done without sacrificing the world around us. We have already made tremendous progress both in academia and in industrial labs throughout the world, showing the potential associated with chemistry in water. The discoveries are here for the taking; we only need to learn the new 'rules' that apply, and then to follow Nature’s lead!"
This article is free to read in our open access, flagship journal Chemical Science: Bruce Lipshutz et al., Chem. Sci., 2019, Advance Article. DOI: 10.1039/C8SC05618H. You can access our 2019 ChemSci Picks in this article collection. Read more like this