The synthesis and properties of a number of novel branched Jatropha curcas L. oil (JO) derivatives containing vicinal di-ester units in the fatty acid chains are reported. Both the length (acetyl vs. hexanoyl) and the stereochemistry of the vicinal di-ester units (cis vs. trans) were varied. The compounds were prepared by two different synthetic approaches using catalytic chemistry. The first approach involves epoxidation of JO using a Sharpless epoxidation with methyltrioxorhenium as the catalyst to give epoxidized JO (1), followed by an esterification reaction with the corresponding anhydrides using ammonium-12-molybdophosphate (AMP) as catalyst to give trans-di-esters of JO (4a, 4b). The second approach is based on the dihydroxylation of JO using either the Prilezhaev method, resulting in trans-diols of JO (2), or the Upjohn method using osmium tetroxide as catalyst to give cis-diols of JO (3). In subsequent steps, the diols were esterified with acetic- or hexanoic anhydride using dimethylaminopyridine as catalyst to produce the corresponding cis- and trans-di-esters of JO (5a, 5b, 6). The best cold flow properties (lowest pour- and cloud point, crystallization and melting temperature) were obtained for JO with hexanoyl branches in a trans orientation (5b, pour point of -14°C, melting point of -5°C, and crystallization temperature of -25°C) and these values are considerably better than for the JO source.Practical applications: Jatropha curcas L. oil (JO) is a toxic oil with potential applications not only as a green biodiesel but also as a feedstock for the oleochemical industry. The toxicity prohibits the use in food products but does not interfere with technical applications. Here we report studies on the synthesis of interesting JO derivatives (epoxidized, dihydroxylated, and branched compounds) that could be useful starting materials for a range of derivatives with a broad application perspective. The branched JO derivatives with vicinal di-ester units in the fatty acid chains have cold flow properties (pour- and cloud point, melting point and crystallization temperature) considerably better than the original JO. In addition, the oxidative stability was also improved significantly. These novel branched JO derivatives may have interesting applications as cold-flow improvers for biodiesel or as biolubricants.
- Branched derivatives
- Jatropha curcas L. oil