Phase behavior of novel triacylglycerols derived from metathesis modified plant oils

The cross-metathesis of vegetable oils containing a finite amount of unsaturation with small olefins such as ethylene or 1-butene results in the production of important platform chemicals. However, a largely unused portion of the original triacylglyceride molecule is left unused: a metathesis modified triacylglyceride or MTAG. The byproduct MTAGs are very interesting precursors for many materials; particularly for the synthesis of polyols and polyurethanes because of their shortened acyl chain and terminal double bond structure. The liquid-solid phase behavior of five metathesis modified triacylglycerols (MTAGS) produced when, for instance, canola, soy and palm oils are cross metathesized with ethylene or 1-butene; namely propane-1,2,3-triyl tris dec-9-enoate (DDD), 3-(stearoyloxy) propane-1, 2-diyl bis dec-9-enoate (DDS), 2-(stearoyloxy) propane-1, 3-diyl bis dec-9-enoate (DSD), 1,2-(stearoyloxy) propane-3-diyl bis dec-9-enoate (SSD) and 1,3-(stearoyloxy) propane-2-diyl bis dec-9-enoate (SDS), was comprehensively examined with DSC and XRD. The differences observed in the thermal transition behavior, melting temperatures and polymorphism between these MTAGs and their unmodified natural stearic-oleic TAG counterparts were well correlated with the number of terminal double bonds, number of shortened fatty acid chains, and number and positions of saturated fatty acid chains. The competition between the effects of unsaturation and position of the short moieties explained the distinctive phase trajectories of the MTAGs. The role of the large chain length mismatch (CLM) between the stearic and decenoic moieties was particularly highlighted in the chain length packing. The structure-function relationships established for MTAGs have never been reported before, and are important to the utilization of this feedstock which is growing in volume due to the commercial utilization of olefin cross metathesis of vegetable oils in the manufacture of oleochemicals.