Thermally induced maleation of soybean and linseed oils: From benchtop to pilot plant

Soybean (Glycine max) oil and linseed (Linum usitatissimum) oil were reacted with maleic anhydride (MA) in a thermally induced ene reaction to provide a bio-based alternative to alkenyl succinic anhydrides. Petroleumbased products have traditionally dominated the marketplace because of their low cost, but due to depleting petroleum supplies there is increasing need to develop new materials from sustainable feedstocks. Vegetable oils are renewable resources that are cost-effective and hydrophobic. Reactions of soybean oil and linseed oil with MA were completed in benchtop sealed high pressure and open glass reactors, and in a pilot plant open glass reactor. In contrast to soybean oil, the reaction between linseed oil and MA yielded cross-linked products under most reaction conditions investigated. The reaction between soybean oil and MA was optimized in terms of temperature and time. The products were characterized by 1H NMR, soap numbers and gel permeation chromatography (GPC) analysis. At low MA loading the benchtop sealed reactor was more efficient in terms of MA conversion, while at higher loadings the open reactor was more efficient. The open glass reactor procedure was also tested on a pilot plant scale. These reactions were more efficient at lower loadings, but slightly less efficient than in the benchtop open reactor at the highest loading. Analysis by GPC revealed significant oligomerization and triglyceride degradation in the sealed reactor products. In comparison, the products synthesized in the open glass reactors had significantly less oligomerization and no significant triglyceride degradation. A new procedure developed to quantify unreacted triglycerides in the maleated oils revealed that some of the products obtained contained less than 1 wt% unreacted triglyceride.