Cyclopentene, Ziegler—Natta polymerization

SYNTHESIS Ring-opening polymerization of cyclopentene. Trflns-jxrlypentenamer is produced by Ziegler-Natta polymerization employing a catalyst based on aluminum triethyl/tungsten hexachloride compound. Aluminum diethylchloride/ molybdenum pentachloride compounds may be employed to produce the as isomer. Both macrocycles and linear chains are produced during polymerization. 

Alkene metathesis, a remarkable reaction catalyzed by transition metal catalysts, can be traced back to Ziegler-Natta chemistry as its origin [11], In 1964, Natta et al. reported a new type polymerization of cyclopentene using Mo- or W-based catalyst, without knowing the mechanism. This was the first example of ring-opening metathesis polymerization (ROMP eq. 1.9) [12],... 

Metallocene-based Ziegler-Natta catalysts are capable of polymerizing cyclic monomers without ringopening reactions that are characteristic of heterogeneous Ziegler-Natta catalysts. Kaminsky reported the homopolymerization of cyclic monomers such as cyclobutene, cyclopentene, norbomene, and dimetha-nooctahydronaphthalene (Scheme 22) with MAO-activated zirconocene catalysts. Cyclobutene was approximately 5 times more reactive than cyclopentene, which was more reactive than norbomene. ... 

Example 3.33 Poly(l-Pentenylene) by Metathesis Polymerization of Cyclopentene with a Ziegler-Natta-Catalyst in Solution... 

The preparation of syndiotactic polypropylene is carried out in the 195-230 K range, while the preparation of isotactic polypropylene takes place at 295-365 K if the catalyst is suspended and at 380-425 K in the presence of a homogeneous catalyst. These conditions are very mild compared to those for radical polymerization which is carried out at 295-470 K and 100-300 MPa. Ziegler-Natta catalysts are also utilized in polymerization of 1,3 dienes and cycloalkenes, for example, butadiene, isoprene, cyclobutene, cyclopentene, and dicyclopentadiene. Conjugated dienes may form the... 

Collins, S. Kelly, W. M. The microstructure of poly(cyclopentene) produced by polymerization of cyclopentene with homogeneous Ziegler-Natta catalysts. Macromolecules 1992, 25, 233-237. 

Metallocene/methylaluminoxane (MAO) catalysts can be used to polymerize and copolymerize strained cyclic olefins such as cyclobutene, cyclopentene, norbornene, DMON and other sterically hindered olefins [205-210]. While polymerization of cyclic olefins by Ziegler-Natta catalysts is accompanied by ring opening [10], homogeneous metallocene [211], nickel [212,213], or palladium [214,215], catalysts achieve exclusive double bond opening polymerization. 

Cyclopentene can be copolymerized with ethene or propene by heterogeneous and homogeneous Ziegler-Natta catalysts. Crystalline or elastomeric copolymers are obtained depending on the cyclopentene content and the part of ring-opening or vinyl-type polymerization mechanism. Metallocene/MAO catalysts are very active in the copolymerization of cyclopentene with ethene. In contrast to the homopolymerization of cyclopentene, the cyclic olefin is incorporated into the copolymer chain by 1,2-enchainment. 

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