Catalytic valorization of oil‐derived fatty esters via cross‐metathesis with nitriles

Abstract

The cross‐metathesis of methyl oleate with 3‐pentenenitrile to obtain 2‐undecene, methyl 9‐undecenoate, methyl 11‐cyano‐9‐undecenoate, and 3‐dodecenenitrile was studied at 323 K in a batch reactor using second‐generation Hoveyda–Grubbs (HG) catalysts. Self‐metathesis of methyl oleate was the main undesired secondary reaction. For a 3‐pentenenitrile/methyl oleate reactant ratio (R3PN/MO) of one, the yield () and selectivity () to cross‐metathesis products were 47 and 63%, respectively. The formation of cross‐metathesis products increased with increasing 3‐pentene initial concentrations, essentially because the reaction equilibrium was shifted to higher methyl oleate conversions. Thus, and were 74 and 83%, respectively, at R3PN/MO = 5. Nevertheless, the HG complex was significantly deactivated when high R3PN/MO values were employed.Practical applications: Metathesis reactions are becoming increasingly attractive in the oleochemistry industry because they offer novel routes for the valorisation of unsaturated fatty acid methyl esters (FAME) that are cheap feedstocks obtained by transesterification of natural oils and fats. Recently, the cross‐metathesis of FAME with functionalized olefins such as esters, allylchlorides, and nitriles has been investigated to obtain renewable α,ω‐bifunctional compounds. In particular, the cross metathesis of nitriles with FAME constitutes an attractive synthesis route toward the production of useful polyamide precursors from natural renewable resources. In this work we investigate the cross‐metathesis of methyl oleate with 3‐pentenenitrile, an internal unsaturated nitrile that does not contain conjugated CC and CN bonds. The results presented in this work show that high yields (74%) and selectivities (88%) to cross‐metathesis products are obtained using the second‐generation Hoveyda–Grubbs Ru catalyst.The cross‐metathesis of methyl oleate with 3‐pentenenitrile is studied using the second‐generation Hoveyda–Grubbs Ru complex as homogeneous catalyst. High yields (74%) and selectivities (88%) to cross‐metathesis products are obtained when pentenenitrile/methyl oleate ratios higher than 3 are employed.