Regio- and Stereoselective Polymerization of Bio-based Ocimene by Rare-Earth Metal Catalysts

Coordination polymerization of renewable 19-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex 1, 19-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a-5c. Complexes 1, 4 and 5a-5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity (mmmm>99%). Conversely, complexes 2 and 3 promote 19-ocimene polymerization to produce isotactic cis-1,4-polyocimenes (cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of 19-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced Tg (from -20 degrees C to 79 degrees C and 74 degrees C) and hydrophilicity.