Propene reaction route

With propene, n-butene, and n-pentene, the alkanes formed are propane, n-butane, and n-pentane (plus isopentane), respectively. The production of considerable amounts of light -alkanes is a disadvantage of this reaction route. Furthermore, the yield of the desired alkylate is reduced relative to isobutane and alkene consumption (8). For example, propene alkylation with HF can give more than 15 vol% yield of propane (21). Aluminum chloride-ether complexes also catalyze self-alkylation. However, when acidity is moderated with metal chlorides, the self-alkylation activity is drastically reduced. Intuitively, the formation of isobutylene via proton transfer from an isobutyl cation should be more pronounced at a weaker acidity, but the opposite has been found (92). Other properties besides acidity may contribute to the self-alkylation activity. Earlier publications concerned with zeolites claimed this mechanism to be a source of hydrogen for saturating cracking products or dimerization products (69,93). However, as shown in reaction (10), only the feed alkene will be saturated, and dehydrogenation does not take place. 

Information on propene oxidation to acrolein over a copper catalyst was published recently by Belousov et al. (115). They consider that at a low temperature (320°) acrolein and C02 are formed mainly by two parallel reaction routes... 

Phenol production is typically carried out by add induced conversion of cumene hydroperoxide to phenol and acetone (Hock process). Cumene hydroperoxide is obtained by oxidation of cumene. The cumene feedstock for the latter reaction is provided by Friedel-Crafts alkylation of benzene with propene. Alternative routes (chlorobenzene hydrolysis, cydohexanol dehydrogenation, oxidative decarboxylation of benzoic acid) exist but are of much lower industrial relevance. 

Acrolein is produced via propene oxidation [route (c) in Topic 5.3.2]. The process uses bismuth and phosphorous molybdates as catalyst in a multi-tubular fixed bed reactor at reaction temperatures of 300-450 °C. The reaction is carried out by applying an excess of air to keep the degree of oxygen loading on the catalyst high. The process allows for propylene conversions of 96% and acrolein yields of 90%. The main side-products are acrylic acid, acetic acid, and acetaldehyde. 

In other examples, also involving propargyl carbonates, the parent derivative 86 was first coupled with 87 - obtained by reaction of 5-octyne with the titanium diiso-propoxide - propene complex at -50 °C, providing the titanated vinylallene 88, which on hydrolysis furnished the vinylallenes 89 in good yield [29]. Carbonate 90 in the presence of a Pd° catalyst readily decarboxylated and yielded the allenylpalladium intermediate 91, which could be coupled with various vinyl derivatives to afford the vinylallenes 92. Since X represents a functional group (ester, acetyl), functionalized vinylallenes are available by this route [30]. 

A process, which uses propene bromohydrin as an intermediate, has been extensively studied as a route for the conversion of propene to propylene oxide [62, 63], The electrolyte is an aqueous solution of sodium bromide saturated with propene gas. An undivided flow cell fitted with a graphite anode is used. Overall, propylene oxide and hydrogen are generated in the sequence of cell reactions given in Scheme 2.3. 

The similarity between the measured activation energies for the reaction-limited production of acrolein over Cu20(100) from allyl alcohol in UHV or propene following a 1 atm. exposure gives a clear indication that these reactions involve the same surface intermediate, an allyloxy. This similarity also suggests that the surface intermediates formed by these two routes behave in a chemically similar fashion. For the (100) surface, the Cu -alkoxide surface complex is similar regardless of whether oxygen from... 

Compared with propene, the oxidation of isobutene is more rapid but less selective, yet selectivities of over 75% appear feasible. Combustion is the main side reaction. One would expect that some considerable attention would be shown in the literature to isobutene oxidation as a route to the industrially important methacrylic acid, but this is not the case. Nor is it with the production of methacrylonitrile, analogous to the propene ammoxidation. Only in the patent literature is a high activity noticeable. 

Balaban and his coworkers have developed the diacylation of propene derivatives to provide a useful route to pyrylium salts (61MI22401). It is proposed that the reaction proceeds through acylation of the alkene to a keto carbocation. Elimination of the a-proton involving a cyclic six-membered transition state then leads to the enol (657) and hence the non-conjugated enone. A second acylation and subsequent dehydration yield the pyrylium salt (Scheme 261). 

This reaction is another possible route for the production of methacrylic acid, since isobutyric acid can be obtained by an oxo process from propene and CO. Heteropoly compounds and iron phosphates are so far the most efficient catalysts for the reaction. The favorable role of the presence of an a-methyl group is remarkable for oxidative dehydrogenation, as the heteropoly compounds are not good catalysts for the dehydrogenation of propionic acid (338, 339). 

In the field of thiochemistry, the photocatalytic synthesis of mercaptans represents an interesting chemical route. Schoumacker et al. [60] performed the synthesis of propan-1-thiol by addition of H2S on propene in contact with illuminated Ti02 or CdS catalysts, according to a reaction mechanism implying photogenerated SH radicals. 

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