University of Wisconsin-Madison scientists at the Wisconsin Energy Institute discovered a more sustainable way to produce Tylenol and other household painkillers.
Scientists Steven Karlen and Vitaliy Tymokhin identified an environmentally friendly method to create paracetamol, a key component of painkillers like Tylenol, UW-Madison’s Wisconsin Energy Institute announced earlier this month.
Tylenol is traditionally derived from crude oil and petroleum, which can be damaging to the environment. Now, the painkiller has a greener alternative researchers source by extracting and converting lignin, a plant compound with a similar molecular structure.
What is the painkiller material?
Paracetamol, also known as acetaminophen, has long been a global go-to for temporary fever relief since the 1900s, according to the National Institutes of Health. However, its traditional manufacturing from coal tar or petroleum derivatives has posed environmental concerns, leading to widespread accumulation in water sources worldwide.
In 2019, a team led by UW-Madison biochemistry professor John Ralph and Steven Karlen, a staff scientist at the Great Lakes Bioenergy Research Center at that time, found paracetamol could be obtained from a compound naturally occurring in poplar trees: p-hydroxybenzoate (pHB), found within lignin, a crucial component of plant cell walls.
The duo’s innovative method earned them a patent for synthesizing paracetamol from lignin, which serves as the backbone of certain plants.
However, converting pHB into paracetamol wasn’t efficient to start. While the initial breakthrough demonstrated the chemical feasibility of converting pHB into paracetamol, Karlen said in a press release the process didn’t efficiently convert enough raw material into the final product.
“Lignin is an extremely complex, messy polymer. No two molecules in a plant are exactly the same. It’s very effective for providing structure and defense for the plant, but it’s challenging for us to break down into useable materials,” Ralph, the leader of research team said in an interview in 2019.
Since then, his team has been dedicated to enhancing the process, aiming to make it more efficient and environmentally friendly.
This time around, researchers found pHB can be easily separated through chemical treatment. The process is primarily water-based, employs eco-friendly solvents and operates continuously rather than in batches, rendering it highly suitable for industrial applications.
“We did the R&D to scale it and make it realizable,” Karlen said.
Researchers achieved a 90% conversion rate of raw material into paracetamol by continuously recycling unreacted material in a reactor. Karlen said he anticipates further optimization could raise the yield to 99%.
It holds the potential to create new revenue streams by making cellulosic biofuels — biofuels derived from non-food plant fibers — more cost competitive with fossil fuels.
“You can make dyes like black ink, polymers which can be used in textiles or material application, convert it to adhesives or into stuff like that,” Karlen said.
The research was published in the journal ChemSusChem.
What’s the economic impact of this discovery?
The process will open for commercial licensing through the Wisconsin Alumni Research Foundation, the nonprofit organization that commercializes university discoveries to support ongoing research.
Paracetamol has an annual global market size of approximately $126 million within the trillion dollar pharmaceutical market, per data from Business Research Insights. Its demand spiked in recent years across all regions due to the COVID-19 pandemic, and in 2021, around 5.3 million prescriptions were issued for paracetamol.
“It’s got a huge market and big value,” Karlen said.
At the same time, Karlen's team has enhanced the paracetamol production process along with other drugs, pigments, textiles and biodegradable plastics.
He said this diverse product portfolio could sustain numerous small biorefineries, which would feed into larger hubs without flooding the market.
“As I’m chopping the tree up, it can feed right into a reactor that pulls out the benzamide,” Karlen said. “So you’re never stopping. As fast as your trucks can come in and fill that hopper, you can keep processing.”
