Propylene, acid-catalyzed conversion

Acid-catalyzed conversion, propylene, 83,85/ Acidic surfaces, decavanadate species, 326 Acidification, terephthalate-pill ed hydrotalcite, 142 Acidity catalysts, 244 TSLS complex, 119-127 Activation... 

Figure 8. Route of Acid Catalyzed Conversion of Propylene [6]...

The feasibility of acid-catalyzed direct hydroamination has been demonstrated. Acidic zeolites afford, at low conversions, highly selective formation of ethyla-mine,297,298 isopropylamine,298 and ferf-butylamine,298-301 in the reaction of ammonia with ethylene, propylene, and isobutylene, respectively. Amine formation is explained as a reaction of surface carbocation intermediates with adsorbed or... 

A wide variety of acid-catalyzed reactions besides those described above have been investigated with heteropoly compounds as catalysts. Al203-supported H3PW12O40 (probably decomposed) catalyzed propylene-ethylene codimerization at 573 K to form pentenes with a selectivity of 56% (butenes 17%, hexenes 27%) (224). Propylene oligomerization proceeded on various kinds of salts of H3PWl204o (225). The activities of the salts decrease in the order A1 > Co > Ni, NH4 > H, Cu > Fe, Ce > K. The A1 salt gave trimers with 90% conversion at 503 K. The selectivities to trimer are about 40% for Al, Ce, Co, and Cu, while that of the acid form is 25%. 

The materials thus prepared were examined in an acid-catalyzed reaction-the cracking of cumene into benzene and propylene. The conversions of cumene into benzene at 250 °C over the catalysts with 1, 3, 5,10, and 20wt% W for the impregnated concentration are shown in Figure 17.10. The highest activities for 5%-,... 

Catalytic activity for other acid-catalyzed reactions, polymerization of propylene and dehydration of alcohols, was increased by y-irradiation of silica-alumina. Mitsutani et al. (96) found that a 48% conversion of cyclohexanol was increased to 66% by about 6 X 10 i ev/gm and a 37%... 

The Pd-catalyzed carbonylation proceeds through an oxidative addition-reductive elimination cycle in which the Pd oxidation state cycles between -I- 2 and 0. Thus, there is a tendency for Pd metal to drop out of the catalytic regime. Supported Pd catalysts would conceivably lock the metal in a fixed environment and minimize such losses. In fact, Pd/C and Pd/zeolites with HI or C3H7I as promoters have been employed to carbonylate ethylene and higher olefins in acetic acid. High conversions and yields are obtained at 10 MPa at a 2 3 ratio of CO propylene and a 1 1 ratio of H20 propylene at 100°C. 

According to Olah s investigations the conversion of methyl alcohol over bifunctional acidic-basic catalyst after initial acid-catalyzed dehydration to dimethyl ether involves oxonium ion formation catalyzed also by the acid functionality of the catalyst. This is followed by basic site catalyzed deprotonation to a reactive surface-bound oxonium ylide, which is then immediately methylated by excess methyl alcohol or dimethyl ether leading to the crucial - 2 conversion step. The ethyl methyl oxonium ion formed subsequently eliminates ethylene. All other hydrocarbons are derived from ethylene by known oligomerization-fragmentation chemistry. Propylene is formed via a cyclopropane intermediate. The overall reaction sequence is depicted in Scheme 19. 

Polymerization of propylene is catalyzed by phosphoric acid distributed as a thin film on quartz particles. An empirical equation is proposed (Langlois Walkey, Petroleum Refiner, p 29, August 1942) for this conversion, namely,... 

It has previously been reported that hydrotalcite catalyzes the aldol condensation of acetone (25). Polyoxometalates are known to dehydrate alcohols due to their acidic nature (IS ). In order to compare the relative basicity of polyoxometalate-pillared hydrotalcites to that of hydrotalcite itself, a variety of hydrotalcites were screened for 2-propanol conversion (Table II). This reaction is known to give propylene when the catalyst contains acidic sites (such as alumina) and acetone when the catalyst contains basic sites (such as magnesium oxide). 

There are reports [592-594] on the dimerization of propylene catalyzed by heterogenized (ir-allyDnickel halides. Polymer-anchored -ir-allylic nickel complexes similar to nonsupported complexes are found to be effective catalysts for propylene dimerization after activation with a Lewis acid such as EtAlCL (molar ratio of Al/Ni = 15 5). Using a crosslinked resin as a support, the dimerization can be performed continuously, since the catalytic centers remain active for a long time without any further addition of aluminum cocatalyst. The release of metals during this reaction is low. The reactions are carried out either in bulk propylene or in chlorobenzene solution. The conversion reaches 95% at room temperature. The product has the composition of 2% dimethylbutenes, 67% methylpentenes, and 31% hexenes. Hexene content obtained with polymer-anchored nickel catalyst... 

Allylic Oxidation. The Wacker reaction and related palladium-catalyzed oxidations which proceed via nucleophilic attack on coordinated alkene have been widely practiced in industry to produce acetaldehyde, acetone, and vinyl acetate. An alternative pathway is available to alkenes in the coordination sphere of palladium(ll) complexes, which could lead to another important family of oxidation products. Insertion into the allylic C-H bond of 1-alkenes gives TT-allyl complexes which, on attack by external nucleophiles, would produce a family of allylic oxidation products including a,fi-unsaturated alcohols, carbonyl compounds, and carboxylic acids. Electron- withdrawing anionic ligands such as trifluoroacetate enhance the ability of the palladium center to insert into C-H bonds in this manner [26] (Fig. lA). Catalytic conversion of propylene to allyl acetate has been achieved in high selectivity in the presence of catalytic quantities of palladium(ll) trifluoroacetate [27]. 

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