Probability Propene

From the propylene reaction three principal sulfur-containing products have been found propylene episulfide, methyl vinyl mercaptan (probably propene-l-thiol), and allyl mercaptan. Rates of product formation as a function of propylene pressure are given in Table VIII. It can be seen that the two types of mercaptans are formed in nearly equal yields, while the ratio fimer pten/Repi umde again increases with pressure, but the limiting yield is only half of that obtained for ethylene. 

A variable pressure oil pump was used in this distillation. Approximately 10 g of a volatile component, consisting mostly of hexamethyl-disiloxane, was obtained at room temperature (15 (in) before the forerun. The forerun contained the desired product and mineral oil from the n-butyllithium solution. The pot residue was about 5 g. The submitters find the disilyl compound thus obtained is contaminated with a trace amount of mineral oil and 4-6% of a vinylsilane, probably 2-methyl-l-trimethylsiloxy-3-trimethylsilyl-2-propene. This impurity becomes quite significant if the reaction medium is less polar than the one described (e.g., too much hexane from n-butyllithium is allowed to remain behind). The spectral properties of the desired product... 

Propene and 1-butene, respectively, are produced in this free radical reaction. Higher hydrocarbons found in steam cracking products are probably formed through similar reactions. 

The low ee values probably derive from partial racemization of the 3-(4-methylphcnylsu finyl)-l-propene prior to reaction. b Temperature 21 °C. 

Note also that (1) d° Ta alkyhdene complexes are alkane metathesis catalyst precursors (2) the cross-metathesis products in the metathesis of propane on Ta are similar to those obtained in the metathesis of propene on Re they differ only by 2 protons and (3) their ratio is similar to that observed for the initiation products in the metathesis of propane on [(=SiO)Ta(= CHfBu)(CH2fBu)2]. Therefore, the key step in alkane metathesis could probably involve the same key step as in olefin metathesis (Scheme 27) [ 101 ]. 

This will be investigated in future work. The acetone which is also formed shows a behaviour independent of the acrolein as the intermediate of reaction forming this is probably propan-2-ol (not detected in our experiments) instead of propene, this lack of relationship is not unexpected. 

Calorimetric investigation of a Diels Alder reaction between propenal and a triene, which had caused problems on scale-up, showed, after the exotherm due to the Diels Alder reaction, and from a temperature a litle above 200°C, a second, more exothermic, reaction with a very fast pressure rise which burst the ARC can employed. This is presumably aromatisation of the alkenylcyclohexenealdehyde first formed, with probable liberation of hydrogen and carbon monoxide. 

Besides methane and hydrogen, other products observed were mainly ethane, ethylene (probably due to propane cracking), propene which are shown in figure 3. Minor amounts of benzene and toluene were also found but these products could not be quantified because their slow desorption from the zeolite s channels. 

By the time the concentration of monomer is low, the back-skip of the polymer chain to the less-hindered site is faster than the formation of the high-energy alkene coordinated intermediate (IV). For this reason, at low propene concentrations and elevated temperatures isotactic sequences are formed. The probability of monomer coordination at the aspecific site (IV) is enhanced when the propene concentration increases. The consequence is that single stereoerrors [mrrm] are introduced in the isotactic polymer chain. 13C-NMR was able to prove the mechanism because a... 

The CVD catalyst exhibits good catalytic performance for the selective oxidation/ammoxida-tion of propene as shown in Table 8.5. Propene is converted selectively to acrolein (major) and acrylonitrile (minor) in the presence of NH3, whereas cracking to CxHy and complete oxidation to C02 proceeds under the propene+02 reaction conditions without NH3. The difference is obvious. HZ has no catalytic activity for the selective oxidation. A conventional impregnation Re/HZ catalyst and a physically mixed Re/HZ catalyst are not selective for the reaction (Table 8.5). Note that NH3 opened a reaction path to convert propene to acrolein. Catalysts prepared by impregnation and physical mixing methods also catalyzed the reaction but the selectivity was much lower than that for the CVD catalyst. Other zeolites are much less effective as supports for ReOx species in the selective oxidation because active Re clusters cannot be produced effectively in the pores of those zeolites, probably owing to its inappropriate pore structure and acidity. 

Special interest attaches to the cyclic aliphatic hydrocarbons. Cyclopropane can be converted to oligomers by cationic catalysis [75, 76], and these appear to be essentially linear but whether they are really different from the polypropenes formed under the same conditions from propene is not yet settled. The initiation most probably involves formation of a non-classical cyclopropyl ion [77], as in alkylations with cyclopropane [78],... 

In MeOH the hydride reacts with higher a-olefins, propene, 1-hexene and 1-hexadecene with formation of only the linear insertion product, probably for steric reasons. In all the insertion products, the alkyl ligand presents the /f-agoslic interaction. At room temperature, the insertion of ethene is quantitative whereas with propene an appreciable amount of the hydride is present, with 1-hexene the hydride prevails, with 1-hexadecene only the hydride is present. The fact that the position of the insertion equilibrium strongly depends on the chain length of the alkyl substituent is probably connected with the high steric hindrance of the ligand [115]. 

Water-soluble l,3-bis(di(hydroxyalkyl)phosphino)propane derivatives were thoroughly studied as components of Pd-catalysts for CO/ethene (or other a-olefins) copolymerization and for the terpolymerization of CO and ethene with various a-olefins in aqueous solution (Scheme 7.17) [59], The ligands with long hydroxyalkyl chains consistently gave catalysts with higher activity than sulfonated DPPP and this was even more expressed in copolymerization of CO with a-olefins other than ethene (e.g. propene or 1-hexene). Addition of anionic surfactants, such as dodecyl sulfate (potassium salt) resulted in about doubling the productivity of the CO/ethene copolymerization in a water/methanol (30/2) solvent (1.7 kg vs. 0.9 kg copolymer (g Pd)" h" under conditions of [59]) probably due to the concentration of the cationic Pd-catalyst at the interphase region or around the micelles which solubilize the reactants and products. Unfortunately under such conditions stable emulsions are formed which prevent the re-use... 

This surface reaction would involve a change in the cyclopentadienyl hapaticity prior to SiO-H activation by the metallic species. Loss of cyclopentadiene by reductive elimination would then occur to provide an allyl palladium(ll) surface species, probably stabilized by a silanol group, in which the oxygen atom acts as a 2e donating ligand. However, when the temperature is raised significant carbon contamination has been evidenced by TPD and TPO experiments. These results are consistent with the absence of further SiO-H activation to eliminate propene [57]. 

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