Propene, selective formation

Selective formation of 2,2,3,3,3-pentafluoropropan-l-ol (1) is achieved using 80% aqueous hydrofluoric acid or hydrogen fluoride/sulfuric acid mixtures.210 Furthermore, hexafluoro-propene reacts selectively under such modified conditions to give 2,3.3,3-tctrafluoro-2-(tri-fluoromethyl)propan-1-ol (2).210 Symmetrical fluoro-containing ethers 3 are obtained by reaction of 1,1-difluoro- or 1,1-dichloroethene, respectively, with 15% paraformaldehyde in hydrogen fluoride (1-chloroethene reacts analogously).204,21 1,212... 

The selective formation of propene observed at the early reaction stage is interpreted by a mechanism involving a metallocyclic intermediate on an Fe ensemble site, similar to the homogeneous organometallic reaction mechanism (207) ... 

Pettit et al. (J06) earlier proposed this propagation mechanism to explain the selective formation of propene in the reaction between ethylene and /i-methylene diiron carbonyl complexes, as shown in the following scheme ... 

The 1 1 Sb-V and 1 1 5 Nb-V-Si systems only were tested at the different space velocity of 100 ml min" g". Almost all the prepared systems exhibited propane conversions of about 30% and propene selectivities higher than 20%. The most selective catalysts with respect to propene formation were the 1 1 Nb-V prepared via the hydrolytic method and 1 1 Sb-V systems (Scshs ca 40%). The 1 1 Sb-V and 1 1 5 Nb-V-Si prepared via the non-hydrolytic method gave the best results in terms of propane conversion and yield in propene. In these two cases, while the higher conversion is in contradiction with... 

The model of the ODH of propane on NiMo04 catalyst, based on a simplified mechanism taking into account the formation of propene and its further oxidation to carbon oxides may be used both with transient and steady state results. In the first case, the evolution of partial pressures of propene and carbon oxides (lumped into COJ is reproduced. When applied to steady state results, the model gives a good representation of the reaction rate, but overestimates the propene selectivity. It should be stressed, that the mechanism proposed takes into account the participation of the lattice oxygen only, both in the formation of propene and in its destruction. Under steady state conditions, where the oxygen gas is present, its participation seems restricted to the propane destruction (but is not significant in the propane activation). 

Recently, Jones et al. have published work on the conversion of diaUylanihnes and arylimines to quinolines [23, 24]. It was found that N-aUylaniUne, when heated in the presence of 10 mol% Co2(CO)8 and 1 atm of CO at 85 °C, leads to the selective formation of 2-ethyl-3-methylquinoHne (Equation (6.1)). Aniline and propene... 

Therefore the bis-sulfone, 2,3-bis(phenylsulfonyl)-l-propene (6), is introduced for the highly selective formation of oxazepines. This bis-sulfone has a three-carbon backbone structure with a vinyl and allylic sulfone, which act in concert to provide unusual reactivity. Bis-sulfone (6), when treated with AT-benzylethanolamine in the presence of triethylamine, gave AT-benzyl-Af-[2-(phenyl-sulfonyl)-2-propyl]ethanolamine (7) in 98% yield, which is then treated with NaOEt causing cycli-zation and formation of oxazepine (8) in 83 /o yield (Scheme 1) <92JOC298>. 

In this way, the direct contact of O2 with the olefin is prevented and the radical process of addition across the double bond is avoided. Reactions (6.18) and (6.19) are slow and the selectivity towards the epoxide in reaction (6.18) strongly depends on the catalyst preparation, the nature of the metal, and the reaction temperature. Using propene, the formation of the epoxide is in concurrence with the formation of acetone and propionaldehyde. Moreover, depending on the preparation of the metal oxide, the same catalyst can push the reaction to the formation of acroleine or even to the total oxidation of propene to CO2 and water [117]. If, instead of the only olefin, a mixture of olefin and CO2 is admitted on the catalyst in its oxidized form, the carbonate is formed which can be recovered by condensation and the excess olefin recycled. 

The ODH of propane over titanium and vanadium containing zeolites and nonzeolitic catalysts revealed that Ti-silicalite was the most active. The addition of water caused an increase in selectivity, probably due to a competitive adsorption on the active sites. The reaction is proposed to occur on the outer surface of the Ti-silicalite crystallites on Lewis acid sites, and a sulfation of the catalyst, which increases the acidity of these sites, results in a further increase of the catalytic activity. The maximum conversion obtained was 17% with a propene selectivity of up to 74% [65]. Comparison of propane oxidation and ammoxidation over Co-zeolites shows an increase in conversion and propene selectivity during ammoxidation. For a conversion of 14%, 40% propene selectivity was obtained with ammonia, whereas, at 10% conversion the propene selectivity was only 12% with oxygen. The increase in activity and selectivity can be due to the formation of basic sites via ammonia adsorption [38]. 

Hitzler et al. (316) report the Friedel-Crafts alkylation of mesitylene (C6H3Me3) and anisole with propene or 2-propanol using a heterogeneous polysiloxane-supported solid acid catalyst (Degussa s Deloxan) in a small fixed-bed continuous reactor (10-ml volume) using SCF propene or CO2 as the reaction solvent. For the alkylation of mesitylene with propene at 160-180°C and 200 bar, yield of the monoalkylated product (l-isopropyl-2,4,6-trimethylbenzene) was only approximately 25% due to the formation of the dialkylated product as well as dimers and trimers of propene. Selectivity to the monoalkylated product was significantly higher (40% yield) for alkylation with 2-propanol in scCOa. 

Figure 4.32. Volcano type behaviour. Effect of Uwr on the rates of C02, N2> N20 formation and on the selectivity to N2 during NO reduction by propene on Pt/p"-Al20j.98,99 Reprinted from ref. 98 with permission from Elsevier Science.

In the case of NO reduction by propene, the only detectable reaction products were CO2, N2, N2O and H2O. The overall mass balance was found to close within 5% as observed by a combination of GC and mass spectroscopic analyses. Figure 3 shows the effect of varying the catalyst potential on the rate of production of CO2, N2, N2O and on the selectivity towards nitrogen formation, Sn2- As can be seen from this figure, both the CO2 and N2... 

Figures 1 shows the catalytic performance of the Fe-BEA catalysts in the temperature range of 250-550 °C. It is clear from the figure that propylene yield depends on particle size of the parent BEA zeolite. Effect of the N20 concentration has been analyzed under reaction regimes RS-1 and RS-2. Increase in N20 concentration resulted in the same propene yields but increased the N20 conversion and decreased the selectivity toward propylene. At higher temperature has been obtained increases in the formation of the molecular oxygen which further accelerates production of the undesired carbon oxides. Thus, at lower feed concentration of N20, i.e. at 1 1 feed ratio of reactants (RS-1), formation of carbon oxides is suppressed and the selectivity of ODHP reaction is...

The most fundamental reaction is the alkylation of benzene with ethene.38,38a-38c Arylation of inactivated alkenes with inactivated arenes proceeds with the aid of a binuclear Ir(m) catalyst, [Ir(/x-acac-0,0,C3)(acac-0,0)(acac-C3)]2, to afford anti-Markovnikov hydroarylation products (Equation (33)). The iridium-catalyzed reaction of benzene with ethene at 180 °G for 3 h gives ethylbenzene (TN = 455, TOF = 0.0421 s 1). The reaction of benzene with propene leads to the formation of /z-propylbenzene and isopropylbenzene in 61% and 39% selectivities (TN = 13, TOF = 0.0110s-1). The catalytic reaction of the dinuclear Ir complex is shown to proceed via the formation of a mononuclear bis-acac-0,0 phenyl-Ir(m) species.388 The interesting aspect is the lack of /3-hydride elimination from the aryliridium intermediates giving the olefinic products. The reaction of substituted arenes with olefins provides a mixture of regioisomers. For example, the reaction of toluene with ethene affords m- and />-isomers in 63% and 37% selectivity, respectively. 

The proposed Re6 cluster (8) with terminal and bridged-oxygen atoms acts as a catalytic site for selective propene oxidation under a mixture of propene, Oz and NH3. When the Re6 catalyst is treated with propene and Oz at 673 K, the cluster is transformed back to the inactive [Re04] monomers (7), reversibly. This is the reason why the catalytic activity is lost in the absence of ammonia (Table 8.5). Note that NH3, which is not involved in the reaction equation for the acrolein formation (C3H6+02->CH2=CHCH0+H20) is a prerequisite for the catalytic reaction as it produces the active cluster structure under the catalytic reaction conditions. 

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