Photoinduced Selective Hydrogenation of Methyl Eleostearate to Monounsaturated Fatty Acid Methyl Esters

Selective hydrogenation of plant oils is an important step in the production of oleochemicals. In this work, a new protocol for photoinduced selective hydrogenation of methyl eleostearates under aqueous conditions has been reported. Using palladium supported on porous graphitic carbon nitride (Pd/pg-C3N4) as a heterogeneous catalyst, formic acid as a hydrogen donor instead of potentially dangerous hydrogen gas, and water as a solvent, methyl eleostearates could be selectively transformed into monounsaturated fatty acid methyl esters (C18:1), which show a high selectivity of >90% under room temperature. The excellent selectivity is attributed to the synergistic effects of the Pd nanoparticles with pg-C3N4. Subsequently, dimethyl 1,19-nonadecanedioate (C19 alpha,omega-diesters) was prepared by isomerizing alkoxycarbonylation of the synthesized C18:1 product. The purity of the C19 alpha,omega-diester monomer is calculated to be higher than 96%, which is critical for the production of polymeric materials.