Catalysis of Organic..

Sanders et al. 379For the purposes of making polyols from these triglycerides, oils which containa high level of unsaturation are desirable. Oils such as soy, canola, and sunflowerare acceptable due to relatively low levels of saturated fatty acids, while feedstockssuch as palm oil are considered unusable without further purification or refinementdue to high levels of saturated fatty acids. Table 1 outlines the composition ofseveral oils (3).Table 1. Fatty acid content of selected vegetable oils in weight percentSoybean Sunflower Canola PalmPalmitic – C16(0) 11 6 4 44Stearic - C18(0) 4 5 2 4Oleic - C18(1) 22 20 56 40Linoleic – C18(2) 53 69 26 10Linolenic – C18(3) 8 0 10 0MethanolysisThe transesterification of triglycerides with methanol is a simple and straightforwardprocess. It is commercially practiced worldwide in the production of FAMEs, whichhave become popular as a replacement for diesel known as “biodiesel”. The processconsists of three separate equilibrium reactions that can be catalyzed by both acidsand bases.(4) The overall process is described in Figure 3. Phase separation of theglycerin is the predominant driving force for this process.RRROOOOOOR O OMeBase+ MeOH +R O OMeROOMeFigure 3. The methanolysis of triglycerides is an equilibrium reaction which isgenerally base catalyzed commerciallyHOHOHOIndustrial processes tend to favor base catalysis, since they have loweractivation energies allowing the reactions to be carried out near or just above roomtemperature (5). Further, the carbonate or caustic bases are relatively inexpensiveand easily separated with the glycerin product.HydroformylationThe important criteria for catalyst selection in the hydroformylation of FAMEs areactivity, stability and catalyst-product separation. For this process, the feed is