Abstract
Cardanol (a mixture of phenols with C-15 aliphatic unsaturated chain in meta position, manufactured from cashew nut shell liquids) is an abundant and till now practically waste natural material. An important way leading to its utilization as a renewable source of valuable phenolic compounds is represented by olefin metathesis.
Quaternary ammonium tagged Ru complex of Hoveyda-Grubbs type immobilized on SBA-15 mesoporous molecular sieve by non-covalent interactions was proved as a very efficient catalyst for cardanol metathesis under mild conditions (35 degrees C, toluene, 0.1 mol% of catalyst). The catalyst was used also in cross-metathesis of cardanol with alkenes (1-hexene, 1-heptene, 3-hexene, 4-octene) and unsaturated esters (methyl acrylate, 1,4-diacetoxybutene-2) under high yields of cross-metathesis products.
The catalysts exhibited low leaching (from 0.2 ppm to 2.9 ppm Ru in products) and can be used in a continuous flow reactor (cumulative TON = 2500).