Higher alpha olefin

New copolymers with higher alpha olefins Expect superior ultimate properties Tough films, flexible moulding... 

Monflier et al. (1997) have suggested Pd catalysed hydrocarboxylation of higher alpha olefins in which chemically modified P-cyclodextrin (especially dimethyl P-cyclodextrin) is u.sed in water in preference to a co-solvent like methanol, acetone, acetic acid, acetonitrile, etc. Here, quantitative recycling of the aqueous phase is possible due to easy phase separation without emulsions. A similar strategy has been adopted by Monflier et al. (1998) for biphasic hydrogenations for water-in.soluble aldehydes like undecenal using a water-soluble Ru/triphenylphosphine trisulphonate complex with a. suitably modified p-cyclodextrin. 

Alfene [Alfa olefene] Also spelled Alfen. A process for making higher alpha-olefins. Ethylene is reacted with triethyl aluminum, yielding high molecular weight aluminum alkyls, and these are treated with additional ethylene, which displaces the higher olefins. Developed by the Continental Oil Company. 

By adding up to 36% ethylene glycol to the aqueous catalyst phase, the space-time yield could be boosted up to approx. 3 mt m-3 h-1 for propene hydroformylation, a factor of 20 in comparison to the conventional two-phase process without changing the reaction conditions. Because of this surprising speed-up, higher alpha-olefins up to 1-octene are converted with high to acceptable space-time yield (Fig. 22). Up to date this process is not commercialized, but has been tested in a continuous pilot plant. 

The products from the pyrolyses of four higher alpha-olefins have been accounted for by an empirical model involving three competing decomposition pathways a molecular decomposition involving a six-membered ring transition state (which yields both propylene and an alpha-olefin with three less carbon atoms than the reactant) and two free radical chain pathways. One free radical channel involves hydrogen abstraction from, the second radical addition to the reactant olefin. The relative contributions of these three paths have been estimated from experimental data from the laboratory pyrolysis of higher alpha-olefins. The pyrolyses were carried out at low conversions in a quartz flow reactor at 475°-550°C. 

It has been assumed that the remaining products are formed by some sort of free radical chain mechanism, but no generalized mechanism like that of Rice s for paraffin pyrolysis has been proposed. Tanaka et al. have been able to simulate product distributions for shorter olefins—up to hexene (10). We shall describe a model for higher alpha-olefin pyrolysis and use it to account for the products from the cracking of several olefins. 

There is little rate data available for addition and abstraction reactions involving higher alpha-olefins. Where such data are available, they have usually been obtained from lower temperature studies (12,13,14), However, the available information indicates that addition should be competitive with abstraction in the temperature range of this study. For example, Steacie s data for ethyl radical reactions with 1-hexene and 1-heptene indicate that at 525°C, the addition rate would be about seven-tenths of the abstraction rate. For dodecene, one would expect this ratio to decrease because of the increase in abstractable hydrogen, but addition should still be a significant pathway. For methyl radicals and H atoms, available data (13,14) indicate that addition is somewhat faster relative to abstraction. 

In the 1990s, an improvement for the gas phase process was developed called "condensed mode" operation of Unipol reactors (12). This technique greatly expanded capacity of gas phase reactors and product capability by making it more practical to use higher alpha-olefin comonomers such as octene-1. 

Metallocene catalysis is an alternative to the traditional Ziegler-Natta vanadium-based catalysis for commercial polyolefin production, e.g. the use of metallocene-catalyzed ethylene alpha-olefin copolymers as viscosity index modifiers for lubricating oil compositions [23]. The catalyst is an activated metallocene transition metal, usually Ti, Zr or Hf, attached to one or two cyclopentadienyl rings and typically activated by methylaluminoxane. Metallocene catalysis achieves more stereo-regularity and also enables incorporation of higher alpha-olefins and/or other monomers into the polymer backbone. In addition, the low catalyst concentration does not require a cleanup step to remove ash. 

Linear Polyethylenes - Linear polyethylenes are polyolefins with linear carbon chains. They are prepared by copol5mierization of ethylene with small amounts of higher alpha-olefins such as... 

GMAW gas metal arc welding HAO higher alpha olefin... 

No reduction in plant capacity during butene-1 and higher alpha-olefin modified L-LDPE, V-LDPE and U-LDPE. 

Blends included 70-90 wt% of a polymer derived from Wong and Varrall (1994) ethylene and at least rate higher alpha-olefin (e.g.,... 

Krentsel, B. A. Kissin, Y. V. Kleiner, V. J. Stotskaya, L. L. Polymers arul Copolymers of Higher Alpha-Olefins Chemistry, Technology, Applications-, Harsner/Gardner Cincinnati, 1997. 

Villar, M.A, Ferreira, M.L., Co- and terpolymerization of ethylene, propylene, and higher alpha-olefins with high propylene contents using metallocene catalysts, J. Polym. Sci. Part A Polym. Chem. 2001,39 1136-1148. 

Kissin, Y. V, Co-oligomerization of ethylene and higher alpha olefins. 11. Structure of oligomers,/ Polym. Sci., Polym. Chem. Ed., 27, 605, 1989. 

Keim, W., Ethylene oligomerization to higher alpha-olefins, Angew. Chem., 90, 493, 1978. 

Mel nikov, V. M., and Gerasina, M. D., Oligomerization of ethylene to higher alpha-olefins on zirconium containing catalysts, Khim. Prom., 1986, 261 (Russian). 

BA Krentsel, YV Kissin, VJ Kleiner, LL Stotskaya. Polymers and Copolymers of Higher Alpha - Olefins. New York Hanser Publishers, 1997. 

Linear Polyethyienes - Linear polyethylenes are polyolefins with linear carbon chains. They are prepared by copolymerization of ethylene with small amounts of higher alpha-olefins such as 1 -butene. Linear polyethylenes are stiff, tough and have good resistance to environmental cracking and low temperatures. Processed by extrusion and molding. Used to manufacture film, bags, containers, liners, profiles, and pipe. 

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