Simultaneous production of biobased styrene and acrylates using ethenolysis†
Phenylalanine (1), which could be potentially obtained from biofuel waste streams, is a precursor of cinnamic acid (2) that can be converted into two bulk chemicals, styrene (3) and acrylic acid (4), via an atom efficient pathway. With 5 mol% of Hoveyda–Grubbs 2nd generation catalyst, 1 bar of ethylene, and using dichloromethane as solvent, cinnamic acid (2) can be converted to acrylic acid and styrene at 40 °C in 24 h with 13% conversion and 100% selectivity. Similar results are obtained using cinnamic acid esters (methyl, ethyl and n-butyl) as substrates and optimisation leads to higher conversions (up to 38%). For the first time, cross-metathesis of these types of electron deficient substrates was achieved.