Ethylene chain growth

Eig. 1. Ziegler ethylene chain growth. Theoretical (Poisson) distribution of primary alcohols at ( ) 2.5, (- -... 

Ethylene chain growth Flash, TEA scrub, hydrolysis, depolymer... 

Manufacture of Higher Straight-Chain Alcohols by the Ethylene Chain Growth Process... 

It is possible to monitor ethylene chain growth at cationic a-diimine nickel and palladium centers by low-temperature NMR spectroscopy. ° ° Under these conditions, the alkyl ethylene complex on the left of Scheme 2 is the catalyst resting state. (This is... 

This second reaction leads to the small amount of branching (usually less than 5%) observed in the alcohol product. The alpha olefins produced by the first reaction represent a loss unless recovered (8). Additionally, ethylene polymerisation during chain growth creates significant fouling problems which must be addressed in the design and operation of commercial production faciUties (9). 

A.luminum Jilkyl Chain Growth. Ethyl, Chevron, and Mitsubishi Chemical manufacture higher, linear alpha olefins from ethylene via chain growth on triethyl aluminum (15). The linear products are then used as oxo feedstock for both plasticizer and detergent range alcohols and because the feedstocks are linear, the linearity of the alcohol product, which has an entirely odd number of carbons, is a function of the oxo process employed. Alcohols are manufactured from this type of olefin by Sterling, Exxon, ICI, BASE, Oxochemie, and Mitsubishi Chemical. 

The chain-growth catalyst is prepared by dissolving two moles of nickel chloride per mole of bidentate ligand (BDL) (diphenylphosphinobenzoic acid in 1,4-butanediol). The mixture is pressurized with ethylene to 8.8 MPa (87 atm) at 40°C. Boron hydride, probably in the form of sodium borohydride, is added at a molar ratio of two borohydrides per one atom of nickel. The nickel concentration is 0.001—0.005%. The 1,4-butanediol is used to solvent-extract the nickel catalyst after the reaction. 

Addition or chain-growth polymerization involves the opening of a double bond to form new bonds with adjacent monomers, as typified by the polymerization of ethylene to polyethylene ... 

Alternatively, the intermediate acetaldehyde (qv) for this process was obtained from ethylene by the Wacker process (9). A small amount of -butyl alcohol is produced in the United States by the Ziegler-Natta chain growth reaction from ethylene [74-85-1] (10). 

Fig. 63. Molecular arrangement in (a, c) plane of a mixed ethylene-chlorine binary crystal illustrating (a) radical pair formation, (b) single chain growth and (c) chain growth in the vicinity of product line. Molecules labelled 1-4 are ethylene (C2H4), chlorine, chloroethyl radical (C2H4CI) and anti 1,2-dichloroethane (C2H4CI2), respectively.

The basic process steps in the Ziegler process are the synthesis of the tri-ethylaluminum catalyst, chain growth from an ethylene precursor, oxidation, and finally hydrolysis. 

Figure 9.21. The Cossee-Arlman mechanism of chain growth in ethylene polymerization involves the insertion of ethylene in the...

Addition polymers, which are also known as chain growth polymers, make up the bulk of polymers that we encounter in everyday life. This class includes polyethylene, polypropylene, polystyrene, and polyvinyl chloride. Addition polymers are created by the sequential addition of monomers to an active site, as shown schematically in Fig. 1.7 for polyethylene. In this example, an unpaired electron, which forms the active site at the growing end of the chain, attacks the double bond of an adjacent ethylene monomer. The ethylene unit is added to the end of the chain and a free radical is regenerated. Under the right conditions, chain extension will proceed via hundreds of such steps until the supply of monomers is exhausted, the free radical is transferred to another chain, or the active site is quenched. The products of addition polymerization can have a wide range of molecular weights, the distribution of which depends on the relative rates of chain grcnvth, chain transfer, and chain termination. 

We make polyethylene resins using two basic types of chain growth reaction free radical polymerization and coordination catalysis. We use free radical polymerization to make low density polyethylene, ethylene-vinyl ester copolymers, and the ethylene-acrylic acid copolymer precursors for ethylene ionomers. We employ coordination catalysts to make high density polyethylene, linear low density polyethylene, and very low density polyethylene. 

Scheme 4 Mechanism of chain growth for a all Pd(II) polymerizations and ethylene polymerizations with Ni(II), and b a-olefin polymerizations with Ni(II). Specific kinetic data shown for Ni catalyst 1.15b [63]...

The transition metal acts as the active site and the chain growth step in polymerisation of ethylene can be represented as below ... 

Characterization results have been reported for dendrigraft-polylpthylene ox-ide)s of generation Gl, prepared by adding different amounts of ethylene oxide to the initiator core in the side chain growth reaction (Table 9.8). Because of the grafting from method used, the molecular weight of the polyethylene oxide) branches cannot be accurately determined, and hence it is impossible to confirm... 

When the process of chain growth is satisfactorily completed, separation of the three hydrocarbon chains that are connected to the aluminum atom is accomplished by a displacement reaction. The chain-laden aluminum compound (called trialkyl aluminum compounds) is subjected to still higher temperatures and pressure. This causes an ethylene molecule to displace the long linear carbon chain. As the separation is made, triethyl aluminum is reformed, making a recyclable root for another go-around. 

Most addition polymers are formed from polymerizations exhibiting chain-growth kinetics. This includes the typical polymerizations, via free radical or some ionic mode, of the vast majority of vinyl monomers such as vinyl chloride, ethylene, styrene, propylene, methyl methacrylate, and vinyl acetate. By comparison, most condensation polymers are formed from systems exhibiting stepwise kinetics. Industrially this includes the formation of polyesters and polyamides (nylons). Thus, there exists a large overlap between the terms stepwise kinetics and condensation polymers, and chainwise kinetics and addition (or vinyl) polymers. A comparison of the two types of systems is given in Table 4.1. 

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