Plastic waste turned into key ingredients for anti-cancer drugs in Scottish study
EHMB is an important intermediate for the synthesis of several commercially significant products.
SEATTLE (Scrap Monster): A collaborative research project led by the University of St Andrews, in Scotland, UK, has identified a novel route to convert common household plastic waste into a valuable building block chemical used in the synthesis of anti-cancer medicines and other widely used products. The work has demonstrated that polyethylene terephthalate (PET) waste – commonly found in plastic bottles and synthetic textiles – can serve as a feedstock for high-value chemicals.
PET waste is typically recycled either mechanically, reshaping the polymer without changing its chemistry, or chemically, which breaks down the long polymer chains into smaller molecules such as monomers or other useful compounds. Chemical recycling has attracted increasing attention because it can enable the recovery of materials with higher functional and economic value.
In the reported study, the research team showed that a ruthenium-catalysed semi-hydrogenation process enabled PET to undergo controlled depolymerisation. This reaction produced ethyl-4-hydroxymethyl benzoate (EHMB) a compound that is rarely obtained directly from waste plastics.
EHMB is an important intermediate for the synthesis of several commercially significant products. These include Imatinib, a widely prescribed anti-cancer medicine, Tranexamic acid, which forms the basis of medicines used to promote blood clotting, and the insecticide Fenpyroximate. At present, these compounds are produced predominantly from virgin fossil fuels and often require hazardous reagents, which generate substantial quantities of chemical waste.
The researchers reported that the environmental performance of the plastic-derived route compared favourably with conventional industrial production methods. A comparative hot-spot analysis, carried out within a streamlined life cycle assessment framework, indicated that the process could reduce environmental burdens by identifying and mitigating the stages of production responsible for the greatest impacts.
Beyond its use as a pharmaceutical intermediate, the team also demonstrated that EHMB could be converted into a novel polyester that retained the ability to undergo recycling, further extending the potential circularity of the process and reducing reliance on carbon-intensive petrochemical resources.
“We are excited by this discovery, which reimagines PET waste as a promising feedstock for generating high-value active pharmaceutical ingredients and agrochemicals,” said Dr Amit Kumar from the University of St Andrews, School of Chemistry and lead author of the study.
“Although chemical recycling is a key strategy to build a circular economy, many existing technologies lack strong economic feasibility.
“By enabling the upcycling of plastic waste into premium products rather than reproducing the same class of plastics, such approaches could accelerate the transition to a circular economy in a meaningful way,” he added.
Researchers from Merck KGaA, a chemical and pharmaceutical company that collaborated on the study, highlighted the wider implications for sustainable manufacturing saying that pharmaceutical production currently generates substantial quantities of waste per kilogram of product, which has reinforced the urgency to develop innovative chemical processes and raw materials with reduced environmental footprints.
“[And] for catalytic upcycling to become practical, the catalyst must operate efficiently at low loadings and retain activity for extended periods,” said Professor Evgeny Pidko from Delft University of Technology in the Netherlands, the lead collaborating institution on the study.
“All catalysts eventually deactivate, so to understand when and how this occurs is critical to achieve turnover numbers relevant for industrial application.
“In this work, we combined detailed kinetic and mechanistic analysis to understand catalyst behaviour under reaction conditions and used this insight to optimise the system towards record turnover numbers of up to 37,000.
“This underlines the importance of fundamental mechanistic understanding to improve catalyst durability and overall process efficiency,” he concluded.
Courtesy: www.labmate-online.com