Allyl alcohol product distribution

This finding is the consequence of the distribution of various ruthenium(II) hydrides in aqueous solutions as a function of pH [RuHCl(mtppms)3] is stable in acidic solutions, while under basic conditions the dominant species is [RuH2(mtppms)4] [10, 11]. A similar distribution of the Ru(II) hydrido-species as a function of the pH was observed with complexes of the related p-monosulfo-nated triphenylphosphine, ptpprns, too [116]. Nevertheless, the picture is even more complicated, since the unsaturated alcohol saturated aldehyde ratio depends also on the hydrogen pressure, and selective formation of the allylic alcohol product can be observed in acidic solutions (e.g., at pH 3) at elevated pressures of H2 (10-40 bar [117, 120]). (The effects of pH on the reaction rate of C = 0 hydrogenation were also studied in detail with the [IrCp (H20)3]2+ and [RuCpH(pta)2] catalyst precursors [118, 128].)... 

The reactions of the vinylcarbenes 7 and 15 with methanol clearly involve delocalized intermediates. However, the product distributions deviate from those of free (solvated) allyl cations. Competition of the various reaction paths outlined in Scheme 5 could be invoked to explain the results. On the other hand, the effect of charge delocalization in allylic systems may be partially offset by ion pairing. Proton transfer from alcohols to carbenes will give rise to carbocation-alkoxide ion pairs that is, the counterion will be closer to the carbene-derived carbon than to any other site. Unless the paired ions are rapidly separated by solvent molecules, collapse of the ion pair will mimic a concerted O-H insertion reaction. 

PHe = 50 kPa. Product analysis was carried out by gas chromatography. For the temperature progranuned studies on Mo03/Si02, 60 pmol of allyl alcohol or ally iodide were dosed on die samples (0.5g). After the system was purged, a flow of 33 nmol s of He was established, and the product distribution was followed by mass spectrometry as the tenqierature was ramped at 0.17 Ks ... 

Direct irradiation of diazoacetophenone in cyclohexene yields much the same product distribution as that obtained through the intermediacy of triplet sensitizers, indicating that the reactant benzoyl-methylene most likely is a triplet.60 A small amount of nonstereospecific addition to the olefin occurs, but the major reaction is allylic hydrogen abstraction to yield acetophenone and dicyclohexenyl. In alcohol... 

Asymmetric epoxidation, dihydroxylation, aminohydroxylation, and aziridination reactions have been reviewed.62 The use of the Sharpless asymmetric epoxidation method for the desymmetrization of mesa compounds has been reviewed.63 The conformational flexibility of nine-membered ring allylic alcohols results in transepoxide stereochemistry from syn epoxidation using VO(acac)2-hydroperoxide systems in which the hydroxyl group still controls the facial stereoselectivity.64 The stereoselectivity of side-chain epoxidation of a series of 22-hydroxy-A23-sterols with C(19) side-chains incorporating allylic alcohols has been investigated, using m-CPBA or /-BuOOH in the presence of VO(acac)2 or Mo(CO)6-65 The erythro-threo distributions of the products were determined and the effect of substituents on the three positions of the double bond (gem to the OH or cis or trans at the remote carbon) partially rationalized by molecular modelling. 

CO, COi, propene, isobutene, dimethyl ketene, acrolein, allyl alcohol, toluene, styrene, a-methylstyrene, ethylbenzene, glycidol, glycidylmethacrylate product distribution depends on copolymer composition... 

They postulated that either end of the rc-allyl species, which forms initially, has an equal probability of collapsing on a lattice oxygen, and the exchange observed with allyl alcohol indicates that this process is rapid and reversible. The same isotopic product distribution is expected as for the sequential hydrogen removal mechanism shown in Scheme 5.1 and the presence of a a C-O bond in -O-CH2-CH-CH2 could reduce the activation energy for removal of the second hydrogen. 

Effect of Base on Product and Isotopic Distribution for Pulse Reaction of Allyl Alcohol-d2 and Propylcne-d at 320 C° ... 

The in situ generated peroxocomplexes were tested for the catalytic epoxidation of various olefins, such as allyhc alcohols, homoallylic alcohols and non-functionalized olefins. The results of these H2O2 oxidations in an alcohol-water system are summarized in Table 2 for the hydrophilic catalyst A, and in Table 3 for the lipophihc material C. Especially for the more reactive alkenes, the turnover number comes close to the maximum of 300. The epoxide selectivity generally exceeds 90%, with minimal solvolysis. With catalyst A, some substrates gave a lower selectivity. For instance, the product distribution for cyclohexene is 65% epoxide, 27% of allylic oxidation products and only 4% of the diol. The epoxycyclohexane selectivity increases to 91% with the hydrophobic material C. 

FIGURE 7.16 Intramolecular acyclic terpene derivatives isommzation through the formation of allyUc cationic species and the effect of the resorcin[4]arene capsule on the product distribution of the reaction for (a) allyl alcohols and corresponding (b) acetate esters as substrates. (Adaptedfrom Ref. [66] with permission of Nature Publishing.)... 

The oxidation of nondeuteriated allyl alcohol (3) under Wacker conditions gave a complicated reaction mixture because of side reactions. The main products are shown in Scheme 12. The 2-hydroxypropanal (4) and hydroxyacetone (5) products arise from Wacker-type oxidation, while acrolein arises from direct hydride extraction from the alcohol carbon. As would be expected from the mechanism of the Wacker reaction, allyl-l,l-d2 (3a) and allyl-3,3-d2 (3b) alcohols gave the same hydroxypalladation adduct and thus the same distribution of denteriated 2-hydroxypropanals, 4a and 4b (Scheme 12). The deuterium isotope effect, A h/A d = 4a/4b = 1.9, has the same value found previously for oxidation of l,2-ethene-r/2- ... 

Interestingly, attempts to use the bis-allylic alcohol as the substrate in the analogous reaction led to isolation of the ferrilactone complex (61) as the major product, accompanied by a trace of the trimethylenemethane complex. Conversely, reaction in THF at room temperature resulted in a complete reversal of the product distribution [256] (Scheme 136). The reasons for this are currently unclear. 

At 26.7 mbar pressure 40% weight toss main product is 2,4-diphenyl thiophene at least 11 unidentified minor products CO2, H2O, butene, isobutene, dimethyl ketene, styrene, methacrylic acid, succinic-type 5-membered cyclic anhydrides Chlorotrifluoroethylene, styrene, HQ, chloropentafluoropropene, ethene, chloroethene, totuene, a-melhylstyiene, dimer and trimer structures with some unsaturation S1F4 (fiom reaction of HF with glass). Distribution of products varies with polymer composition CO, CO2, propene, isobutene, dimethyl ketene, acrolein, allyl alcohol, toluene, styrene, cl-methylstyrene, ethylbenzene, glycidol, glycidylmethacrylate product distribution depends on copolymer composition... 

When electron transfer reactions of olefins are carried out in nucleophilic solvents (alcohols) or in the presence of an ionic nucleophile (KCN/acetonitrile/2,2,2-trifluoroethanol), the major products formed are derived by anti-Markovnikov addition of the nucleophile to the olefin. In several cases, nucleophilic capture completely suppresses dimer formation [122, 143]. It is important to realize that the observed mode of addition reflects the formation of the more stable (allylic) intermediate and cannot be interpreted as evidence for the charge density distribution in the radical cation. 

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