Ethylene dependence

Sclair A process for polymerizing ethylene. Depending on the co-monomer used, the product can be linear low-density polyethylene (LLDPE) or high-density polyethylene (HDPE). Developed by DuPont in 1960 and widely licensed. Engineered by Uhde under the name Sclairtech. Nova Chemicals (Alberta) acquired the technology in 1994. 

Ethylene-dependent mechanism terminates flower life after successful pollination as a way to benefit survival of the species. Usually, in species with short-lived flowers, such an ethylene-dependent termination apparently is not beneficial as the life of individual flowers is short anyway. Similarly, in species with numerous flowers in one flower head in which continuous visits of pollinators are required, ethylene-dependent termination is not beneficial. ... 

Typical heterogeneous Ziegler catalysts operate at temperatures of 70 100°C and pressures of 0.1 2 MPa (15 300 psi). The polymerization reactions are carried out in an inert liquid medium (e.g, hexane, isobutane) or in the gas phase. Molecular weights of LLDPE resins are controlled by using hydrogen as a chain-transfer agent. Reactivities of a-olefins in copolymerization with ethylene depend on two factors the size of the alkyl groups attached to their double bonds and the type of catalyst,... 

Politycka, B. Ethylene-dependent activity of phenylalanine ammonia-lyase and lignin formation in cucumber roots exposed to phenolic allelochemicals. Acta Soc Bot Pol 1999 68 123-127. 

Our purpose in focusing on 10-12 in this discussion is to show how toxicity may require a balance between various factors. For example, the results of extensive studies suggest that the carcinogenic behavior of halogenated ethylenes depends upon102,103,106 ... 

Tlte product distribution in the reaction involving ethylene depends on the reaction conditions [17-19], According to the work carried out by Union... 

The behaviour of ethylene depends upon the geometry of the substrate. On Ir(100)-(5 X 1) at room temperature C—C scission occurs, whereas on Ir(lOO)-(1 X 1) dehydrogenation occurs giving a stretched and bent acetylene molecule. 

Ton, I, Van Pelt, J.A., Van Loon, L.C., and Pieterse, C.M.J. (2002). Differential effectiveness of salicylate-dependent and jasmonate/ethylene-dependent induced resistance in Arabidopsis, Mol. Plant-Microbe Interact., 15, 27-34. 

Fundamentally, the manufacture of ethylene involves two principri operations (1) the formation of ethylene and (2) separation from other materials present. There are at least eight well-recognized methods for the formation of ethylene, and at least five processes have been employed for its separation and purification. Present processes for the formation of ethylene depend upon either the pyrol3rtic or the catalytici converrion of paraflSnic hydroc bons. Those most generally used in this country employ... 

The economics for the production of ethylene depends to a large extent on the prices for feedstocks and co-products. In the United States the ... 

Industrial-scale electric cracking can be used not only for the production of acetylene but also for production or co-production of ethylene, which was demonstrated in particular by Huls, Chem. W, Germany. The relative yield of acetylene and ethylene depends on temperature and duration of the process, the type of quenching, the composition of initial products, and so on. The maximum production of acetylene usually corresponds to temperatures of 1800-2000 K (for CH4 and CsHg) and temperatures of 1600-1880 K (for heavier... 

The adsorption rate of gas molecules, such as nitrogen, oxygen, hydrogen, and ethylene, depends strongly on the pore size of the MSC the adsorption rate of a gas becomes slower for the MSC with the smaller pore size. The temperature also governs the rate of adsorption of a gas because of activated diffusion of adsorbate molecules in micropores the higher the temperature, the faster the adsorption [47-49]. 

The values for substituted ethylenes depend largely on the substitution pattern, for example, tetrasubstituted ethylenes often possess a small /Id due to steric inhibition to complex formation. Disubstituted olefins (unsym-metric) show an upfield shift at one olefinic carbon and a downfield shift at the other. Data for these complexes are given in Table XLIII. 

As an alternative feedstock, chemists turned to ethylene, already available in huge quantities from the refining of natural gas and petroleum. The process of producing acetic acid from ethylene depends on the fact that in the presence of catalytic amounts of Pd + and Cu + salts, ethylene is oxidized by molecular oxygen to acetaldehyde. 

Fig. 8.3. Principal variants of relative positions of the energy levels of substituted carbenes CXY and ethylene depending on the substituents X, Y a electrophilic carbenes b nucleophilic carbenes c ambiphilic carbenes. The order of energy level is adhered to for CCI2 (a) and C(NH2)2 (b)...

The world s 140 million metric tons of annual ethylene capacity almost exclusively employs steam cracking of hydrocarbon feedstocks [5]. The majority of the feedstocks come from petroleum refining, such as by cracking of naphtha, but some producers use liquefied natural gas as a feedstock. In Brazil, where sugar cane is plentiful, Braskem has built a 200,000 metric ton per year ethylene plant based upon the dehydration of sugar-derived ethanol [6]. In the United States, natural gas liquids, a mixture of ethane, propane, butane, and other hydrocarbons, are available from shale deposits. The ethane is separated and cracked to make ethylene. Depending on the cost of oil and natural gas, this can be an economic advantage. In 2012, about 70% of United States ethylene production was from ethane [7]. 

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