Continuous flow homogeneous alkene metathesis with built-in catalyst separation

Continuous flow homogeneous alkene metathesis using a supported ionic liquid phase (SILP) catalyst with CO2 as a transport vector allows the self-metathesis of methyl oleate with only a slight loss of activity for at least 10 h; cross-metathesis of dimethyl maleate with methyl oleate ceases after 3 h, but the catalyst remains active for methyl oleate metathesis. The reasons for this unusual behaviour are explored and a practical system for the cross-metathesis of methyl oleate with dimethyl maleate, under batch conditions, is described.