Conjugation, epoxidation, and cationic polymerization of fish oils

Abstract

Wilkinson's catalyst [RhCl(PPh3)3] has been used to conjugate fish oil in high yields under very mild reaction conditions. A catalyst load of 1 mol % RhC1(PPh3)3, 1.25 mol % (o-CH3C6H4)3P, and 2.5 mol % SnCl2·2H2O in ethanol solvent at 600C for 2 days will produce 82% conjugated fish oil in a 91% yield. The extent of conjugation appears to be partially dependent on reaction time. The Sharpless epoxidation procedure has also been employed to epoxidize fish oil. Using 0.5 mol % CH3ReO3, 12 mol % pyridine, and 1.5 equivalents of 30% hydrogen peroxide (aq) in methylene chloride solvent at 25 0C for 6 hours, fish oil may be 100% epoxidized in an 86% yield. Decreasing the amounts of CH3ReO3 and pyridine used in the reaction results in partially epoxidized fish oils. The BF3·OEt2-catalyzed copolymerization of fish oil and conjugated fish oil with alkene additives produces thermoset plastics. Copolymers ranging from rubbers to hard plastics may be synthesized by changing the amounts of additives used. Polymers prepared from conjugated fish oil are harder and shinier than those prepared from normal fish oil. Differential scanning calorimetric (DSC) analysis of the fish oil thermosets indicates that these are highly crosslinked materials with no apparent thermal phase transitions. The fish oil thermosets are thermally stable up to 250-300°C and partially soluble in CH2Cl2, THF, and DMF solvents. The insoluble materials remaining after the extraction of the fish oil thermosets are thermally stable up to 400-450°C. Epoxidized fish oil has been prepared and cationically polymerized using BF3·OEt2 to produce a white, powdery polyether. The same reaction performed in the presence of THF produces a powdery, light-brown copolymer.