Hexadiene phenoxyimine

Scheme 11 Mechanism of polymerization of 1,5-hexadiene by phenoxyimine-Ti complex...

Ho, S. C. H. Wu, M. M. Xiong, Y. Novel cyclopolymerization polymers from nonconjugated dienes and 1-alkenes. PCT International Patent Application WO 95/06669 (Mobil Oil Corp.), March 9,1995. Hustad, P. D. Coates, G W. Insertion/isomerization polymerization of 1,5-hexadiene synthesis of functional propylene copolymers and block copolymers. J. Am. Chem. Soc. 2062,124, 11578-11579. Hustad, P. D. Tian, J. Coates, G. W. Mechanism of propylene insertion using bis(phenoxyimine)-based titanium catalysts an unusual secondary insertion of propylene in a group IV catalyst system. J. Am. Chem. Soc. 2002,124,3614-3621. 

SCHEME 2.12 Polymerization of 1,5-hexadiene with bis(phenoxyimine) titanium catalyst system. 

Bis(phenoxyimine) titanium complexes have also been employed in the living copolymerization of ethylene/cyclic olefins and ethylene/l,5-hexadiene. Utilizing 31/MAO and varying ethylene pressure, a series of poly(E-co-CP)s with different cyclopentene contents were prepared (Fujita and Coates, 2002). When ethylene pressure was low (<1 psi), an almost perfectly alternating copolymer was formed (Mn = 21000 g/mol, Mw/Mn = 1.34, T = 10.1 C). However, the use of higher ethylene pressures (3 psi) resulted in the formation of a random copolymer containing 36 mol% cyclopentene (M = 133000g/mol,Mw/Mn = 1.24, T =—A.S°C). Tri- and multiblock copolymers were synthesized in which the constituent blocks differed in their cyclopentene content. 

Finally, Coates and coworkers found that bis(phenoxyimine) titanium complex 31 was also capable of living 1,5-hexadiene polymerization and 1,5-hexadiene/propylene copolymerization (Hustad and Coates, 2002). Homopolymerization of 1,5-hexadiene with 31/MAO at 0°C produced a high molecular weight polymer with a narrow PDI (M = 268 000 g/mol, Mw/Mn = 1.27). The polymer showed the presence of two distinct units - the expected MCP units as well as 3-vinyl tetramethylene (3-VTM) units. As shown in Scheme 9.4, the MCP units are proposed to arise from 1,2-insertion of 1,5-hexadiene followed by a 1,2-cyclization. However, an initial 2,1-insertion of 1,5-hexadiene followed by a 1,2-cyclization forms a... 

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