Ethylene with olefins

Alternating copolymers of ethylene with olefins containing double bonds in the cis configuration, like ds-2-butene, cyclopentene, cycloheptene,115 and norbomene,116 have been described. Recently also copolymers of carbon monoxide with styrene and styrene derivatives, having syndiotactic117 and isotactic118 configurations, have been synthesized and characterized. 

Table VII. Telomerization of Ethylene with Olefinic Telogens ...

Linear low-density polyethylenes. LLDPEs are copolymers of ethylene with olefins, such as n-butene, n-octene and 4-methyl pentene-1, prepared using metal alkyl polymerization catalysts at low pressure and temperature. Copolymer content is adjusted to control the mechanical properties and degree of crystallinity. In general, they do not contain high proportions of the comonomers, and a typical copolymer with a 0.92 density will have 1-2% comonomer content. 

The co-dimerization of ethylene with olefins has also been studied extensively and has been called hydrovinylation. A seminal example, discovered by Bogdanovic and Wilke, involved the co-dimerization of ethylene and norbornene catalyzed by a (TT-aUyl)nickel catalyst (Equation 22.34). This chemistry and more modem versions of these additions of one olefin C-H bond across another were presented in Chapter 16 on the hydrofunctionalization of olefins. 

The filler role is not confined to inorganic compounds. Polysulfide oligomer processing also employs as fillers numerous organic substances polypropylene powder (M = 10 X 10, particle size 1-5 p.m), polyethylene, or copolymers of ethylene with olefins having three to six carbon atoms [84]. These materials provide stress dissipation on the contact surface between support and sealant, eliminate sealant stratification, and prevent crack forming. 

Copolymers of ethylene with olefin monomers CH2=CH-(CH2) -CH3 and CH2=CH-CH2-CH2-CH(CH3)2 are the most widely used class of industrial copolymers. Most important is linear low-density polyethylene (LLDPE), which is a copolymer involving ethylene and the structural units ... 

The use of silver fluoroborate as a catalyst or reagent often depends on the precipitation of a silver haUde. Thus the silver ion abstracts a CU from a rhodium chloride complex, ((CgH )2As)2(CO)RhCl, yielding the cationic rhodium fluoroborate [30935-54-7] hydrogenation catalyst (99). The complexing tendency of olefins for AgBF has led to the development of chemisorption methods for ethylene separation (100,101). Copper(I) fluoroborate [14708-11-3] also forms complexes with olefins hydrocarbon separations are effected by similar means (102). 

In acetic acid solvent, ethylene gives 1,3-propanediol acetates (46) and propylene gives 1,3-butanediol acetates (47). A similar reaction readily occurs with olefinic alcohols and ethers, diolefins, and mercaptans (48). 

Chlorine can be removed by either activated carbon adsorption or by reaction with olefins such as ethylene over-activated carbon at temperatures of 30—200°C (44). Addition of Hquid high boiling paraffins can reduce the chlorine content in the HCl gas to less than 0.01% (45). 

Densities and crystallinities of ethylene—a-olefin copolymers mosdy depend on their composition. The classification ia Table 1 is commonly used (ASTM D1248-48). VLDPE resias are usually further subdivided iato PE plastomers of low crystallinity, 10—20%, with densities ia the range of 0.915—0.900 g/cm, and completely amorphous PE elastomers with densities as low as 0.860 g/cm. ... 

Commercial production of PE resias with densities of 0.925 and 0.935 g/cm was started ia 1968 ia the United States by Phillips Petroleum Co. Over time, these resias, particularly LLDPE, became large volume commodity products. Their combiaed worldwide productioa ia 1994 reached 13 X 10 metric t/yr, accouatiag for some 30% market share of all PE resias ia the year 2000, LLDPE productioa is expected to iacrease by 50%. A aew type of LLDPE, compositioaaHy uniform ethylene—a-olefin copolymers produced with metallocene catalysts, was first introduced by Exxon Chemical Company in 1990. The initial production volume was 13,500 t/yr but its growth has been rapid indeed, in 1995 its combiaed production by several companies exceeded 800,000 tons. 

Most Kaminsky catalysts contain only one type of active center. They produce ethylene—a-olefin copolymers with uniform compositional distributions and quite narrow MWDs which, at their limit, can be characterized by M.Jratios of about 2.0 and MFR of about 15. These features of the catalysts determine their first appHcations in the specialty resin area, to be used in the synthesis of either uniformly branched VLDPE resins or completely amorphous PE plastomers. Kaminsky catalysts have been gradually replacing Ziegler catalysts in the manufacture of certain commodity LLDPE products. They also faciUtate the copolymerization of ethylene with cycHc dienes such as cyclopentene and norhornene (33,34). These copolymers are compositionaHy uniform and can be used as LLDPE resins with special properties. Ethylene—norhornene copolymers are resistant to chemicals and heat, have high glass transitions, and very high transparency which makes them suitable for polymer optical fibers (34). 

Dow catalysts have a high capabihty to copolymetize linear a-olefias with ethylene. As a result, when these catalysts are used in solution-type polymerisation reactions, they also copolymerise ethylene with polymer molecules containing vinyl double bonds at their ends. This autocopolymerisation reaction is able to produce LLDPE molecules with long-chain branches that exhibit some beneficial processing properties (1,2,38,39). Distinct from other catalyst systems, Dow catalysts can also copolymerise ethylene with styrene and hindered olefins (40). 

Chromium Oxide-Based Catalysts. Chromium oxide-based catalysts were originally developed by Phillips Petroleum Company for the manufacture of HDPE resins subsequendy, they have been modified for ethylene—a-olefin copolymerisation reactions (10). These catalysts use a mixed sihca—titania support containing from 2 to 20 wt % of Ti. After the deposition of chromium species onto the support, the catalyst is first oxidised by an oxygen—air mixture and then reduced at increased temperatures with carbon monoxide. The catalyst systems used for ethylene copolymerisation consist of sohd catalysts and co-catalysts, ie, triaLkylboron or trialkyl aluminum compounds. Ethylene—a-olefin copolymers produced with these catalysts have very broad molecular weight distributions, characterised by M.Jin the 12—35 and MER in the 80—200 range. 

Other Higher Oleiins. Linear a-olefins, such as 1-hexene and 1-octene, are produced by catalytic oligomerization of ethylene with triethyl aluminum (6) or with nickel-based catalysts (7—9) (see Olefins, higher). Olefins with branched alkyl groups are usually produced by catalytic dehydration of corresponding alcohols. For example, 3-methyl-1-butene is produced from isoamyl alcohol using base-treated alumina (15). 

Olefin Complexes. Silver ion forms complexes with olefins and many aromatic compounds. As a general rule, the stabihty of olefin complexes decreases as alkyl groups are substituted for the hydrogen bonded to the ethylene carbon atoms (19). 

Hydrogen sulfide reacts with olefins under various conditions forming mercaptans and sulfides (108,109). With ethylene it can react to ultimately give diethyl sulfide (110). With unsymmetrical olefins, the direction of addition can be controlled by the choice of either a free-radical initiator, including ultraviolet light, or an acidic catalyst (110) ... 

Numerous organic reactions of sulfur monochloride are of practical and commercial importance. Of particular importance is the reaction of sulfur monochloride with olefins to yield various types of addition products (142). With ethylene, the severe vesicant bis(2-chloroethyl) sulfide [505-60-2] (mustard gas) forms with elemental sulfur and polysulfides (see Chemicals IN war). Propylene reacts similarly ... 

Boron Bromide. Approximately 30% of BBr produced in the United States is consumed in the manufacture of proprietory pharmaceuticals (qv) (7). BBr is used in the manufacture of isotopicaHy enriched crystalline boron, as a Etiedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in semiconductor doping and etching. Examples of use of BBr as a catalyst include copolymerization of butadiene with olefins (112) polymerization of ethylene and propylene (113), and A/-vinylcarbazole (114) in hydroboration reactions and in tritium labeling of steroids and aryl rings (5). 

Zieglei-type catalysts based upon Co, Ni, and Fe and in the presence of aluminum alkyls codimeiize butadiene with olefins such as ethylene. 

Carbon monoxide also reacts with olefins such as ethylene to produce high molecular weight polymers. The reaction of CO with ethylene can be initiated by an x-ray irradiator (62) or transition-metal cataly2ed reactions (63). The copolymeri2ation of ethylene with carbon monoxide is cataly2ed by cationic Pd (II) complexes such as Pd[P(CgH )2] (CH CN) (BF 2 where n = 1-3. With this catalyst, copolymeri2ation can be carried out at 25°C and pressures as low as 2.1 MPa. 

Many monomers have been copolymerised with ethylene using a variety of polymerisation systems, in some cases leading to commercial products. Copolymerisation of ethylene with other olefins leads to hydrocarbon polymers with reduced regularity and hence lower density, inferior mechanical properties, lower softening point and lower brittle point. 

Ethylene-cyclo-olefin copolymers have been known since 1954 (DuPont USP2 721 189) but these materials only became of importance in the late 1990s with the development of copolymers of ethylene and 2-norbomene by Hoechst and Mitsui using metallocene technology developed by Hoechst. The product is marketed as Topas by Ticona. By adjustment of the monomer ratios polymers with a wide range of Tg values may be obtained including materials that are of potential interest as thermoplastic elastomers. This section considers only thermoplastic materials, cyclo-olefins of interest as elastomers are considered further in Section 11.10. 

U. Moll and M. Lux, Manufacture of ethylene/alpha olefin copolymers with metallocene catalysts in slurry loop... 

In this process, which has been jointly developed by Institute Francais du Petrole and Chinese Petroleum Corp., the C4 feed is mainly composed of 2-butene (1-butene does not favor this reaction but reacts differently with olefins, producing metathetic by-products). The reaction between 1-butene and 2-butene, for example, produces 2-pentene and propylene. The amount of 2-pentene depends on the ratio of 1-butene in the feedstock. 3-Hexene is also a by-product from the reaction of two butene molecules (ethylene is also formed during this reaction). The properties of the feed to metathesis are shown in Table 9-1. Table 9-2 illustrates the results from the metatheses reaction at two different conversions. The main by-product was 2-pentene. Olefins in the range of Ce-Cg and higher were present, but to a much lower extent than C5. 

The formation of the active metal-carbon bond as a result of the interaction of low-valent ions of the transition metal with olefin is the most intriguing step of the polymerization process by one-component catalysts. The possibility of the formation of the transition metal-carbon bond resulting from the reaction of titanium low-valent ions with ethylene is shown in Dzsabiev et al. (182) ... 

---