Paracetamol, the omnipresent pain reliever found in countless households worldwide, may soon radically adjust its manufacturing method. For more than a century, this medicine, known as acetaminophen in the United States and Japan, has been manufactured using chemicals derived from coal tar or crude oil, raising environmental concerns. However, revolutionary research from the University of Wisconsin-Madison suggests a possible alternative: using the power of trees, notably poplar wood.
The evolution of paracetamol: from coal tar to poplar trees
Paracetamol, often known as acetaminophen, was first produced in the 1800s and has since become one of the most widely used over-the-counter medications for pain and fever around the world. It was added to the World Health Organization’s Model List of Essential Medicines and sold under brand names such as Tylenol and Panadol. However, its origins in nonrenewable petrochemicals earned it the nickname “coal tar analgesic.”
In the beginning, the starting material for paracetamol’s commercial production was phenol, produced from the distillation of coal tar, which has analgesic characteristics. Industrial phenol was eventually manufactured primarily from crude oil, although it still posed environmental difficulties.
How does this transformation work?
The study team, led by Professor John Ralph, a professor of biochemistry at UW-Madison, and staff scientist at the Great Lakes Bioenergy Research Center, Steven Karlen, developed a method for synthesizing paracetamol from lignin, a complex organic polymer found in poplar trees. Lignin is the structural backbone of these trees, and while its chemical structure is complex, the scientists devised a method to easily break it down into useful components. Karlen explains, “You can make dyes like black ink, polymers for textiles, or convert it into adhesives. It has a large market and high value.
The method consists of three steps: breaking down plant-based p-hydroxybenzoate (pHB) into p-hydroxybenzamide (pHBA), turning pHBA into p-aminophenol, and acetylating p-aminophenol to create paracetamol. This process produces an excellent yield of over 90 percent, with high purity levels that could exceed 99 percent with further refinement.
Advantages over traditional methods
The new methodology has various advantages over traditional production processes. It largely uses water-based and green solvents, eliminating reliance on environmentally hazardous chemicals. Furthermore, it functions as a continuous reaction process, as opposed to batch reactions, which are more suitable for industrial scaling.
Karlen elaborates, “As I’m chopping the tree up, it can feed right into a reactor that pulls out the benzamide. So you’re never stopping. As fast as your trucks can come in and fill that hopper, you can keep processing.”
Scaling up: a solution for the future
Looking ahead, the potential influence of the green revolution goes far beyond pain treatment. In 2022, the global market for pHBA, a critical intermediate in the process, was estimated to be worth $66 to 85 million. The researchers believe that by building a network of biorefineries that process poplar wood, production may be scaled up to meet demand sustainably. They envision smaller biorefineries feeding into larger hub refineries, resulting in a market for derived products worth millions to billions of dollars.
The transition from trees to Tylenol represents more than just a change in production methods; it shows a dedication to environmental responsibility and sustainable innovation. With continuous study and collaboration, this ground-breaking strategy has the potential to reshape not only the pharmaceutical sector but also our collective path to a more sustainable future.
Source study: ChemSusChem—Production of biomass-derived p-hydroxybenzamide: Synthesis of p-aminophenol and paracetamol
