Ethene temperature

C. It occurs in natural gas. May prepared by reduction of ethene or ethyne by hydrogen under pressure in the presence of a nickel catalyst, or by the electrolysis of a solution of potassium elhanoate. It has the general properties of the paraffins. Used in low-temperature refrigeration plant. 

Note 2. At higher temperatures some of the product might decompose into ethene and vinylketene. 

The acetylenedicarboxylate 17 is a reactive compound and is carbonylated smoothly at room temperature to give the ethanetetracarboxylate 18 as the main product and ethene- and ethanetricarboxylates as minor products. Acetylenemonocarboxylate is converted into the ethanetricarboxylate 19 as the main product with several other products[l8]. 

A more efficient agent than peroxy compounds for the epoxidation of fluoro-olefins with nonfluonnated double bond is the hypofluorous acid-acetomtrile complex [22] Perfluoroalkylethenes react with this agent at room temperature within 2-3 h with moderate yields (equation 13), whereas olefins with strongly electron-deficient double bond or electron-poor, sterically hindered olefins, for example l,2-bis(perfluorobutyl)ethene and perfluoro-(l-alkylethyl)ethenes, are practically inert [22] Epoxidation of a mixture of 3 perfluoroalkyl-1-propenes at 0 C IS finished after 10 mm in 80% yield [22] The trifluorovinyl group in partially fluorinated dienes is not affected by this agent [22] (equation 13)... 

Even more important is the stereoregular catalytic polymerization of ethene and other alkenes to give high-density polyethene ( polythene ) and other plastics. A typical Ziegler-Natta catalyst can be made by mixing TiCU and Al2Eti in heptane partial reduction to Ti " and alkyl transfer occur, and a brown suspension forms which rapidly absorbs and polymerizes ethene even at room temperature and atmospheric pressure. Typical industrial conditions are 50- 150°C and 10 atm. Polyethene... 

Bond density surfaces are also superior to conventional models when it comes te describing chemical reactions. Chemical reactions can involve many changes in chemica bonding, and conventional formulas are not sufficiently flexible to describe what happen (conventional plastic models are even worse). For example, heating ethyl fonnate t( high temperatures causes this molecule to fragment into two new molecules, foraii( acid and ethene. A conventional formula can show which bonds are affected by ths reaction, but it cannot tell us if these changes occur all at once, sequentially, or in soms other fashion. 

A photoinduced hydrogen atom transfer in cw-l-(2-pyrrolyl)-2-(2-quino-line)ethene was reported (94JA3171).The rate eonstant A (5 —> 4) increases with increasing temperature from 2.1 10 s at 15.8°C to 7.7 10 s at 39.5°C, giving an aetivation energy of 9.4 keal/mol. 

The distribution of the products obtained from this reaction depends upon the reaction temperature (Figure 5.1-4) and differs from those of other poly(ethene) recycling reactions in that aromatics and alkenes are not formed in significant concentrations. Another significant difference is that this ionic liquid reaction occurs at temperatures as low as 90 °C, whereas conventional catalytic reactions require much higher temperatures, typically 300-1000 °C [100]. A patent filed for the Secretary of State for Defence (UK) has reported a similar cracking reaction for lower molecular weight hydrocarbons in chloroaluminate(III) ionic liquids [101]. An... 

The first example of homogeneous transition metal catalysis in an ionic liquid was the platinum-catalyzed hydroformylation of ethene in tetraethylammonium trichlorostannate (mp. 78 °C), described by Parshall in 1972 (Scheme 5.2-1, a)) [1]. In 1987, Knifton reported the ruthenium- and cobalt-catalyzed hydroformylation of internal and terminal alkenes in molten [Bu4P]Br, a salt that falls under the now accepted definition for an ionic liquid (see Scheme 5.2-1, b)) [2]. The first applications of room-temperature ionic liquids in homogeneous transition metal catalysis were described in 1990 by Chauvin et al. and by Wilkes et ak. Wilkes et al. used weekly acidic chloroaluminate melts and studied ethylene polymerization in them with Ziegler-Natta catalysts (Scheme 5.2-1, c)) [3]. Chauvin s group dissolved nickel catalysts in weakly acidic chloroaluminate melts and investigated the resulting ionic catalyst solutions for the dimerization of propene (Scheme 5.2-1, d)) [4]. 

As early as 1972 Parshall described the platinum-catalyzed hydroformylation of ethene in tetraethylammonium trichlorostannate melts [1]. [NEt4][SnCl3], the ionic liquid used for these investigations, has a melting point of 78 °C. Recently, platinum-catalyzed hydroformylation in the room-temperature chlorostannate ionic liquid [BMIM]Cl/SnCl2 was studied in the author s group. The hydroformylation of 1-octene was carried out with remarkable n/iso selectivities (Scheme 5.2-13) [66]. 

Solid catalysts for the metathesis reaction are mainly transition metal oxides, carbonyls, or sulfides deposited on high surface area supports (oxides and phosphates). After activation, a wide variety of solid catalysts is effective, for the metathesis of alkenes. Table I (1, 34 38) gives a survey of the more efficient catalysts which have been reported to convert propene into ethene and linear butenes. The most active ones contain rhenium, molybdenum, or tungsten. An outstanding catalyst is rhenium oxide on alumina, which is active under very mild conditions, viz. room temperature and atmospheric pressure, yielding exclusively the primary metathesis products. 

Catalyst system Temperature (K) Conditions Pressure (10s Nm-2) Weight hourly space velocity (hr-1) Conversion" (%) Selectivity6 (%) Ethene/butene molar ratio" Reference... 

Arenediazonium salts also couple in acetonitrile with another group of activated ethene derivatives, the allylsilanes (Mayr and Grimm, 1992). At low temperatures the... 

The notion of a pnre chemical snbstance can be related to empirically identifiable properties (e.g. sharp melting and boiling temperatures) but is nowadays understood in theoretical terms that are abstract (Johnson, 2002 Taber, 2002a). So hydrogen, methane, diamond, sodium, sodium chloride and polythene - poly(ethene) - are all considered examples of single chemical substances, although they are very different... 

The thermal cracking of a light ffaction of mixed plastics waste was carried out in a fluidised bed reactor and the fractions obtained were analysed by elemental analysis, gas chromatography and ashing. The main components of the waste were PE and PP with a small amount of PS and the bed was fluidised by pyrolysis gas, nitrogen or preheated steam. Experiments conducted at different temperatures and residence times were compared by calculating the crack severity for each experiment. The results obtained revealed that the amounts of ethene and propene obtained by pyrolysis with steam were comparable with those obtained using a commercial steam cracker. 

High-temperature and -pressure free radical polymerization of ethene, to produce low-density polyethene (LDPE). 

Figure 5. The molar fraction Xg of Pt in the topmost atomic layer of the alloy as a function of the bulk molar fraction of Pt-Xb. Curved full line the best fit through the experimental AES data for surfaces in vacuum. The shaded area indicates the range of the steady state molar fraction of Pt, estimated by using different growth-models for the carbon(aceous) layers, calculated for the topmost layer of Pt/Cu alloys in contact with ethene, at ambient temperature. (Reproduced with permission from Ref.34. North-Holland Publ.Co.)...

Figure 6. Characteristic part of the carbon KW AES spectra after 55 min. exposure of 2.I0 nbar ethene at ambient temperature Pt and C peak are not separated in these spectra nevertheless the C-spectrum shows a pronounced graphite structure on pure Pt (c) and much more of the carbidic (or molecular) C on 42% (a) and 63% (b) Pt alloys. (Reproduced with permission from Ref.34. North-Holland Publ.Co.)...

Recently, it has been demonstrated that coordination vacancies on the surface metal cations are relevant to the unique redox reactivity of oxide surfaces]2]. Oxidation of fonnaldehyde and methyl formate to adsorbed formate intermediates on ZnO(OOOl) and reductive C-C coupling of aliphatic and aromatic aldehydes and cyclic ketones on 1102(001) surfaces reduced by Ar bombardment are observed in temperature-prognunmed desorption(TPD). The thermally reduced 1102(110) surface which is a less heavily damaged surface than that obtained by bombardment and contains Ti cations in the -t-3 and +4 states, still shows activity for the reductive coupling of formaldehyde to form ethene]13]. Interestingly, the catalytic cyclotrimerization of alkynes on TiO2(100) is also traced in UHV conditions, where cation coordination and oxidation states appear to be closely linked to activity and selectivity. The nonpolar Cu20( 111) surface shows a... 

Propyhdyne formed from propene on lr4 supported on y-Al203 was observed by IR and NMR spectroscopies [38]. When ethene or propene was brought in contact with oxide-supported lr4 [39,40], Ire [39,40], or Rhe (A.M. Argo and B.C. Gates BC, impubhshed results) in the presence of H2, hydrocarbon hgands were formed (namely, alkyls and /r-bonded alkenes), which have been inferred from IR spectra to be intermediates in hydrogenation to make alkanes, as discussed later. The population of these hydrocarbon ligands on the supported clusters depends sensitively on the conditions, such as reactant partial pressures and temperature. 

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