Diels-Alder reaction mechanism is known to be one of the major reaction mechanisms to produce dimers and polymers during heating process of vegetable oil. However, our NMR study showed no evidence for Diels-Alder products. Soybean oil oxidized at 180 �C for 24 hrs with 1.45 surface area-to-volume ratio showed 36% polymer peak area in GPC, but the DEPT 135 spectrum didn't show any signals of possible Diels-Alder products. A fraction was separated from the oxidized soybean oil by column chromatography, which showing 98% polymer peak area in GPC. But, again, this fraction showed no signals of proposed Diels-Alder products in the DEPT 135 spectrum. Methyl oleate and triolein without a diene required for the Diels-Alder reaction produced 27% and 63% of total polymers, respectively, under the same condition. This indicates that the polymers must be produced by reactions other than the Diels-Alder reaction for these oils. This study shows that the Diels-Alder reaction is not the major reaction to produce polymers during oxidation of soybean oil.

Is it true that polymerization of vegetable oil occurs through Diels-Alder reaction?

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.