Organic chemist challenges the system to find a cleaner way of running reactions
May 28, 2020
By Ian Evans
“Following nature’s lead,” this UC professor is transforming organic chemistry from petroleum-based to a sustainable discipline based on water
Caption: Prof. Bruce Lipshutz (far right) with his team of researchers at the University of California, Santa Barbara.
Dr. Bruce Lipshutz(opens in new tab/window), a professor at the University of California, Santa Barbara, knows first-hand that it’s not easy to challenge a century’s worth of convention in science. But he also knows it can be done, and when it succeeds, it can clear the path for a cleaner, more economically viable future.
His research in chemistry and biochemistry has won him accolades, including the 2011 Presidential Green Chemistry Challenge Award(opens in new tab/window). But the journey has been difficult and the goal ambitious:
Our group’s(opens in new tab/window) crusade is to change the entire field of organic chemistry from something that is historically petroleum-based to a sustainable discipline based on chemistry with water.
Organic chemistry involves research around the structure, properties, and reactions of organic compounds. However, most organic molecules are not water soluble and therefore don’t undergo reactions in water. For about a century and a half, scientists have solved this problem with organic solvents — chemicals mainly from our petroleum reserves that act as the reaction medium, creating an environment for the compounds to respond. These solvents account for about 80–90 percent of the total mass used in any organic reaction, and 80–85 percent of the waste the chemical industry creates(opens in new tab/window). That creates an unsustainable situation, Bruce explained:
Chemists run reactions in organic solvents, they do extractions using water, and then dump the waste solvent and water into a container that eventually gets carted away. And where does it all go? We have big problems like this created by the chemistry enterprise worldwide, and we’re leaving these problems behind for our children and our grandchildren.
It’s not only a question of waste products but of being able to sustain production of chemicals and pharmaceuticals that people have come to depend on, Bruce said, using palladium for an example:
At the rate we’re consuming palladium and given the technology now known used to mine it, we’re going to run out of it in 50 to 100 years. Is that our legacy for the future? Will we just say to society, ‘Sorry, we can’t make these blockbuster drugs anymore because we don’t have access to the needed metal catalysts?’
As the lead of the Lipshutz Research Group, Bruce decided this was a level of waste he could no longer contribute to – and about a decade ago, he realized that he didn’t have to:
It came to me that we could follow nature’s lead. Nature doesn’t have a problem doing chemistry in water, and yet Nature doesn’t only deal in molecules that are soluble in water. There’s chemistry in the human body that involves aqueous and non-aqueous meda. So how does nature do such exquisite chemistry with molecules that are not soluble in water?
“Nature has it all figured out. We saw that as the perfect model.”
In nature, for example, it happens in vesicles, tiny structures within or outside a cell consisting of liquid or cytoplasm enclosed by a lipid bilayer. “Think about it akin to an enzyme pocket,” Bruce said. “Things go in, chemistry happens, things exit – nature has it all figured out. We saw that as the perfect model.”
As such, Bruce and his team focused their research on a similar principle, using nanoreactors in bodies of water – vessels the size of a nanometer particle: “With these nanoreactors, we can take water insoluble substrates and catalysts, and the chemistry happens inside those particles housed in the surrounding water. You put the items to be reacted into the pool of water, which is about 98 percent of the mixture — thus, there is a very limited number of these nanoreactors. The non-water-soluble organic molecules all compete for access to these nanoreactors, and that’s where the ‘magic’ takes place. And once the reaction is complete and the product is isolated, everything is recyclable; the water, the nanoreactors, and the catalyst.”
Since then, Bruce and his team have demonstrated that it’s possible to replicate much high-profile chemistry research using this method:
We’ve published several research papers that show how to do Nobel Prize winning chemistry like this; in water at ambient temperatures. Suzuki-Miyaura couplings(opens in new tab/window), Heck reactions, Negishi couplings, metathesis(opens in new tab/window) — all these things can be done very effectively in water using our technology. Also included is Nobel Prize-winning enzymatic catalysis done exclusively in water as well. Hence, we can now do both, chemo- and bio-catalysis in one pot, sequentially.
Bruce H. Lipshutz, Catalyst: Imagine Doing Chemistry at No Cost … to the Environment!(opens in new tab/window)Chem (Sept 2018)
Bruce, who sits on the Editorial Board for Elsevier journals Trends in Chemistry(opens in new tab/window), Current Research in Green and Sustainable Chemistry(opens in new tab/window) will be a keynote speaker at Elsevier’s forthcoming Reaxys PhD Prize(opens in new tab/window) Symposium 2020, with his talk ‘Chemo- & Bio-catalysis in Water: Our Only Ticket to Sustainability'. In fact, the people behind the Reaxys prize have a history of promoting green chemistry through the Elsevier Foundation-ISC(opens in new tab/window). Elsevier also runs the Green and Sustainable Chemistry Conference, taking place in November 2020.
Advice for chemistry mavericks
Does Bruce have any advice for other chemists who are looking to challenge established ways of doing things?
If you’re doing something transformational, you’re going to come up against a lot of resistance. You have to find ways to keep going, you have to keep driving the message.
Bruce pointed to the example of a person he describes as one of his most brilliant students:
He’s probably the future of green chemistry developed and applied to organic synthesis. At the moment, as an assistant professor, I see he’s reliving my life simply because they see him as ‘threatening.’ People are shooting him down at every stage. I tell him, ‘Persevere, get through it – you must survive. The world really needs you.’
That’s the message for anyone trying to drive a sustainable future in chemistry. You are the future. If it hasn’t happened, you’re going to make it happen. It’s very challenging, but it’s the right thing to do.
Bruce himself chalks part of his success and recognition to pure luck, noting that even following his Presidential award, he still struggled to find funding for the work that won the award:
I remember at the award talk I gave in Washington. I took two minutes at the end to emphasize to whoever was listening that we must devote some national funding to green chemistry. I don’t care how it gets done – we chemists created these problems and only we can solve them.
Fortunately, at that time, companies like Novartis and PHT International stepped in to help him continue this work. Today, several others are also contributing to enable his group to continue its mission.
“I got lucky,” Bruce said. “Had these sources not come through, I don’t know where I would be today. But perseverance was important as well. I felt then as I do now: obligated to pursue what I knew at that time. And I’m totally convinced today that chemistry in water is our future. Fortunately, as others begin to appreciate this approach to synthesis, things are getting better.”
“Young people get it.”
Indeed, Bruce notes that as environmental concerns become ever more pressing, more focus in being placed on clean, sustainable solutions. He also notes the number of young chemists joining the discipline, determined to make a difference and build a future they can be proud of:
We just went through graduate recruitment, and honestly, with the number of incoming talented chemists dedicated to making their contributions to green chemistry, I find myself with an embarrassment of riches. It’s a question of figuring out how many we can afford to take and how much space we have.
The bottom line here is: young people get it, and quickly. They want to be part of the movement that shifts the field and encourages chemists to do things differently. They realize immediately that this is their planet, and they’re going to inherit what we leave behind.