Novel Method of Using Carbonylation to Obtain Polyester from Castor Oil

One of the significant tasks in modern materials science and an important challenge to be addressed for sustainable industrial production to have a future is the development of future technologies that are not based on mineral oil and can be used for synthesizing plastics and chemicals.

Castor oil plant. (Image credit: Pixabay)

It is necessary to devise and test a number of theoretical ideas and laboratory processes to resolve difficulties and problems that arise in relation to the natural materials before the investigation of prospective applications for materials obtained from renewable resources. Recently, Professor Stefan Mecking has described one such concept in an ongoing study on acquiring polyester from castor oil, titled “Synthetic Polyester from Plant Oil Feedstock by Functionializing Polymerization” and published in the Angewandte Chemie journal.

Together with his coworker Dr Ye Liu, an Alexander von Humboldt Fellow and the first author of the study, Stefan Mecking introduces an innovative way of extracting polyester from oils and fats, more specifically from castor oil. Undecenol is a familiar and chemically established building block that can be extracted from castor oil.

Our idea was to interlink many of these molecules to form one large molecule, a plastic molecule. We wanted the whole process to be effective and readily accomplishable ‘in one go’.

Stefan Mecking, Professor, University of Konstanz

One end of the Undecenol molecule includes a group of alcohols and the other end includes a double bond. It was critical to interlink these two groups to create an ester group such that simultaneous linkage with long-chain molecules (i.e., plastics) is enabled. To achieve the intended material properties, such long-chain bonds are essential. One of the significant general difficulties in relation to these processes is the identification of appropriate catalysts.

They are especially important because the reaction leading up to the formation of the desired long-chain molecules must be incredibly effective and proceed without any variance.

Stefan Mecking, Professor, University of Konstanz

In order to produce the polyester as reported in their study, the chemists employed carbonylation to extract the ester groups. “The problem is that Undecenol reacts with another smaller molecule, an aldehyde. If this happens, it does not become part of the molecule chain, which means that it gets lost,” stated Stefan Mecking, summing up the essence and great success of his study.

The scientists could avoid this loss and obtain the polyester effectively by using the appropriate catalysts. While creating the catalysts, they also devised the conceptual steps needed for adjusting the melting point of the products. “Due to the insights we gained, we should be able to infer how to handle the melting points of other long-chain substrates,” concluded Stefan Mecking, referring to prospective transfer applications of his concept for other renewable resources that are even more readily available compared to castor oil.


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