Olefin methanol conditions

Another possible reason that ethylene glycol is not produced by this system could be that the hydroxymethyl complex of (51) and (52) may undergo preferential reductive elimination to methanol, (52), rather than CO insertion, (51). However, CO insertion appears to take place in the formation of methyl formate, (53), where a similar insertion-reductive elimination branch appears to be involved. Insertion of CO should be much more favorable for the hydroxymethyl complex than for the methoxy complex (67, 83). Further, ruthenium carbonyl complexes are known to hydro-formylate olefins under conditions similar to those used in these CO hydrogenation reactions (183, 184). Based on the studies of equilibrium (46) previously described, a mononuclear catalyst and ruthenium hydride alkyl intermediate analogous to the hydroxymethyl complex of (51) seem probable. In such reactions, hydroformylation is achieved by CO insertion, and olefin hydrogenation is the result of competitive reductive elimination. The results reported for these reactions show that olefin hydroformylation predominates over hydrogenation, indicating that the CO insertion process of (51) should be quite competitive with the reductive elimination reaction of (52). 

SAPO molecular sieves, with their mild acidity, are a very interesting alternative to attain high selectivities for light olefins. The conditions of synthesis, dealumination, and cation exchange seem to be very important for obtaining a catalyst with a good performance for methanol conversion into light olefins. 

Triol 984 is converted to the 6-membered benzylidene acetal 1009 with benzaldehyde and PTSA, and the remaining hydroxyl group is then oxidized to an aldehyde (1010) under Swem conditions. A Z-selective Wittig reaction provides a separable mixture of 1011 and its E-isomer (92 8). The stereochemical outcome of the Wittig reaction is strongly dependent on the nature of the alkoxyaldehyde and the polarity of the solvent. In this case polar solvents favor the formation of the Z-olefin, methanol being optimum. Treatment of 1011 with acetic acid gives the desired butenolide 1012 in nearly quantitative yield. 

Stork and Williard have noted that when certain olefinic a,/8-epoxy-ketones are treated with hydrazine in methanol, conditions normally resulting in the Wharton reaction, anomalous behaviour resulting in cyclization is observed.Thus the epoxy-ketone (185) was converted into the bicyclic alcohol (186) in 85% yield. 

The dlenophlle, 3-acetyl-2(3H)-oxazolane, Is an attractive Intermediate for the synthesis of vicinal aminoalcohols with cIs configurations. It reacts with 1,3-dienes, even under quite mild conditions, to form (4+2) cycloadducts. Its high reactivity with deactivated 1,3-dienes Is noteworthy. This property is present also in 2(3H)-oxa201one which can be obtained easily through solvolysis of 3-acetyl-2(3H)-oxa2olone In methanol. 3-Acetyl-2(3H)-oxazolone, on UV irradiation In the presence of a sensitizer, combines easily with olefins to form (2+2) cycloadducts, the hydrolysis of which leads to the class of cis-2-aminocyclobutanols. 

Depending on the electronic state of azafulvalene and the reaction conditions, simple nucleophiles such as amines or alcohols show a different behavior. Upon heating methanol reacted with azafulvalenes as electron-rich olefins by addition to the central double bond (64BSF2857 67LA155). Using the TAF 77 (Ar = Ph), the addition reaction in a neutral benzene-ethanol solution required several days to obtain a minor amount of 147, while the reaction proceeded rapidly in the presence of a catalytic amount of potassium hydroxide (79JOC1241). Tlie yellow-colored adduct 147 can be reconverted to the quinoid starting material by irradiation (Scheme 58). 

Water-soluble dicationic palladium(II) complexes [(R.2P(CH2)3PR.2)Pd-(NCMe)2][BF4]2 proved to be highly active in the carbon monox-ide/ethene copolymerization under biphasic conditions (water-toluene). In the presence of an emulsifier and methanol as activator, the catalytic activity increased by a factor of about three. Also higher olefins could be successfully incorporated into the copolymerization with CO and the terpolymerization with ethene and CO.184... 

NMR spectroscopy is essential for the structure determination of carotenoid isomers because the TI-NMR signals of the olefinic range are characteristic for the arrangement of the isomers. The stereoisomers of astaxanthin, as shown in Figure 4.16, can be separated on a shape-selective C30 capillary column with methanol under isocratic conditions. 

In a recent publication, Chang and Silvestri have discussed this reaction in detail (109). They reported that under conditions of low (ca. 10%) conversion substantial amounts of dimethyl ether, formed by the reversible dehydration of methanol, are present and 78% of the primary hydrocarbon product consists of C2-C4 olefins. Also, if dimethyl ether, in the absence of water, is used instead of methanol, essentially the same hydrocarbon product distribution is obtained. On the basis of these observations, Chang and Silvestri suggest the reaction path shown below ... 

Using a protocol for tandem carbonylation and cycloisomerization, Mandai et al.83 were able to synthesize cyclopentene and cyclohexene derivatives in high yield, including fused and 5/>/>0-bicycles (Scheme 25). The cyclohexene Alder-ene products were not isolable methanol addition across the exocyclic double bond (in MeOH/ toluene solvent) and olefin migration (in BuOH/toluene solvent) were observed. The mechanism of methanol addition under the mild reaction conditions is unknown. In contrast to many of the other Pd conditions developed for the Alder-ene reaction, Mandai found phosphine ligands essential additionally, bidentate ligands were more effective than triphenylphosphine. 

When CH3OH is adsorbed first, the strongly adsorbed CH OH is transformed into ethers, olefins, paraffins and aromatics, m a similar way, when it was the only reactant present (7) (A). C2H4 remains inactive below 623 K. At this temperature, it begins to react as it is shown by the NMR signals in the paraffinic region (B). It can be assumed that in such conditions, ethylene alkylates aromatics obtained from methanol. 

Lifetimes of the ionic intermediates of nucleophilic substitution are generally correlated to the pathways followed under given reaction conditions. Information on the lifetimes of ionic intermediates formed by bromine addition to olefins in methanol, as determined by the azide clock method, do not allow the different reaction pathways to be distin-... 

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... 

---