Butene stereoregular polymer

The original, simplest polyolefins, polyethylene and polypropylene, continue to dominate the scene, even after two decades, to such an extent that no other polyolefin even appears on the production charts. Nevertheless, a great many (we may assume all) available olefins have been tested, and many have been found capable of being converted to stereoregular polymers. As was mentioned above, poly(l-butene) and poly(4-methy1-1-pentene) are being offered commercially and may be expected to achieve significant volume in the future. Isotactic and syndiotactic polystyrene are of much theoretical interest (26) but are not yet commercial products. 

The major end-use of iodine is in catalysis (e.g., the Monsanto process for producing acetic acid). Titanium tetraiodide and aluminum iodide are also significant in the dehydrogenation of butane and butene to butadiene, and in the preparation of stereoregular polymers. The second major end-use of iodine is as a stabilizer in the manufacture of nylon, for converting resins, tall oil and other wood products to more stable forms, while the third major use is as additives for animal and human food (iodization of salt and mineral mixtures). 

Fig. 7. Hydride shift in the pol3maerization of 3-methyl-l-butene, jdelding crystalline stereoregular polymer.

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

He was a Professor of Industrial Chemistry, School of Engineering, Polytechnic Institute of Milan, Milan, Italy since 1937. He became involved with applied research, which led to the production of synthetic rubber in Italy, at the Institute in 1938. He was also interested in the synthesis of petrochemicals such as butadiene and, later, oxo alcohols. At the same time he made important contributions to the understanding of the kinetics of some catalytic processes in both the heterogeneous (methanol synthesis) and homogeneous (oxosynthesis) phase. In 1950, as a result of his interest in petrochemistry, he initiated the research on the use of simple olefins for the synthesis of high polymers. This work led to the discovery, in 1954, of stereospecific polymerization. In this type of polymerization nonsymmetric monomers (e.g., propylene, 1-butene, etc.) produce linear high polymers with a stereoregular structure. 

It should be added that alternating ethylene/2-butene copolymers can exhibit stereoregularity namely the ethylene/cA-2-butene copolymer, which possesses an erythro-diisotactic structure and is a crystalline polymer. It may be interesting to note that from the formal point of view the alternating eryt/zro-diisotactic ethylene/cA-2-butene copolymer, i.e. erythro-diisotactic poly[ethylene- //-(c/.v-2-butene)], can be treated as isotactic head-to-head and tail-to-tail polypropylene. Isomeric trans-2-bu. ene gives atactic amorphous copolymers with ethylene [2,82]. 

A group of polymers consisting of isotactic, stereoregular, highly crystalline polymers based on butene-1. Their properties are similar to those of polypropylene and linear polyethylene, with superior toughness, creep resistance, and flexibility. 

Aoki and co-workers [46] demonstrated that spectral analysis based on the 2D-INADEQUATE spectrum and the chemical shift calculation via the y-effect is very useful for C-NMR chemical shift assignments of higher a-olefin copolymers. The successful result of this spectral analysis for a stereoregular 1-hutene-propylene copolymer confirms the reliability of this method. Eurther, the conformational states of the side chain in the 1 -butene unit is evaluated through the chemical shift calculation by considering the side-chain conformation. Therefore, this method is applicable to the analysis of the C-NMR spectrum and of the side-chain conformation in various olefin homo- and co-polymers. 

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