Propene condensed phase

In a series of papers Gross et provide experimental evidence that ionization of cyclopropane in the gas phase results in the formation of a trimethylene cation radical (2) isomerization of cold 2 to ionized propene (3) can be ruled out. The authors, moreover, stress that the structural changes of ionized cyclopropane in both the gas phase and in condensed phase are entirely analogous. 

Grassie and co-workers a.l23, a.l24] found that under inert conditions at temperatures above about 210 °C the polyurethane linkage disappears without any volatile products being formed, and the initial degradation step is seemingly a simple depolymerisation reaction. The two monomers are the primary products, and all the other products, which include carbon dioxide, butadiene, tetrahydrofuran, dihydrofuran and water as volatile products and carbodiimide and urea amide in the condensed phase, are formed from the monomers in a complex set of secondary reactions while they are diffusing from the hot polymer. This is unlike under oxidative conditions, whereby the first step involves the scission of the polyurethane molecule into primary amine, carbon dioxide and propenyl ether species, the latter leading to propene formation. The mechanism is reduced to a... 

Hoechst-Ruhrchemie (now Celanese) reported that no detectable losses of rhodium occur. We assume that propene is stripped from the aldehyde product and finally distillation of the aldehyde is conducted to separate the branched (8%) and linear product (92%). Note that the amounts of water lost in the aldehyde phase have to be replaced. Note also that by-products arising from aldol condensation, if any, are separated from the catalyst together with the product. These heavy ends end up in the bottom of the product distillation, which is advantageous, as the bottom can be sent to an incinerator. In processes such as the Shell process (Figure 7.6), the heavy end is a mixture of... 

Dioxanes (337) are also conveniently obtained by acid-catalyzed condensation of oxiranes with glycols, while use of ethanolamine gives morpholine (338). Base-catalyzed reaction of oxiranes with a-amino acids and esters gives tetrahydro-l,4-oxazin-2-ones, e.g. propene oxide + RNHCH2C02H — (339). 1,4-Dithianes have been prepared by the dimerization of thiiranes either in the vapor phase or in the presence of acid catalysts. 

The examples described above of the successful use of SILP catalysis were aU gas-phase reactions under conditions where no condensation of substrates or products in the gas stream was possible. (Note that capillary condensation inside the porous network of a SILP catalyst might nonetheless occur under certain circumstances.) This is an important prerequisite for effective SILP catalysis as a continuous flow of liquid could remove the thin film of IL from the support (either by dissolution or mechanical displacement), rendering the catalyst inactive in most cases. In case of propene and 1-butene hydroformylation, the formation of the so-caUed heavies 18 and 19 via aldol condensation of the respective aldehyde products (see Scheme 15.3) was reported to reduce the catalyst activity over time, whereas the selectivity remained unchanged [15]. 

This reaction represents an initiation mechanism for the gas phase polymerization of propene since it results in the formation of the dimer radical cation (C6Hi2, which can sequentially add several propene molecules. The formation of this ion can make the overall process of charge trtmsfer and covalent condensation significantly exotiiermic (27). At higher concentrations of... 

Pb(C2H5)4 is employed as a chain-starter for the alkylation of alkanes or cycloalkanes by alkenes or cycloalkenes [697], and in the liquid-phase oxidation of alkylaromatic hydrocarbons to give hydroperoxides [892]. Pb(C2Hs)4 catalyzes the photochemical addition of HBr [661, 681] or of H2S or mercaptans to alkenes, such as propene [661, 679, 681], and it catalyzes the intermolecular condensation of arylalkanes in sunlight or on heating [684]. 

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