ACYCLIC DIENE METATHESIS (ADMET) POLYMERIZATION - THE SYNTHESIS OF UNSATURATED POLYESTERS

The first acyclic diene metathesis (ADMET) polymerization using the molybdenum catalyst Mo(CHCMe2R)(N-2,6-C6H3-i-Pr2)[OCCH3(CF3)2]2 (R = Me, Ph) is presented. This catalyst is much faster in the metathesis of terminal olefins than its tungsten counterpart. 1,4-Benzenedicarboxylic bis(1-hexenyl) ester, 1,4-benzenedicarboxylic bis(1-pentenyl) ester, 1,4-benzenedicarboxylic bis(1-butenyl) ester, and 1-hexenyl 1-pentenoate successfully undergo ADMET homopolymerization. These polymerizations are initiated under bulk conditions and are continued in solution to produce poly[oxy-5-decenyloxyterephthaloyl], poly[oxy-4-octenyloxyterephthaloyl], poly[oxy-3-hexenyloxyterephthaloyl], and poly(oxy-3-octenyl ester), respectively. No metathesis activity is observed for 1,4-benzenedicarboxylic bis(1-propenyl) ester or 1-hexenyl 1-butenoate due to the negative neighboring group effect. This negative neighboring group effect involves either the coordination of the carbonyl oxygen to the metal center or simply the polarization of the double bond such that the intermediates of the metathesis process are not favored. The copolymerization of 1,4-benzenedicarboxylic bis(1-pentenyl) ester and 1,9-decadiene produces a random copolymer. All polymer structures were determined by IR, H-1 NMR, and C-13 NMR spectroscopy, and number-average molecular weights were determined by end-group analysis and vapor-pressure osmometry. Synthesis, characterization, and the general limitations of this polymerization are discussed.