Catalytic water formation on platinum: a first-principles study.

The study of catalytic behavior begins with one seemingly simple process, namely the hydrogenation of O to H2O on platinum. Despite the apparent simplicity its mechanism has been much debated. We have used density functional theory with gradient corrections to examine microscopic reaction pathways for several elementary steps implicated in this fundamental catalytic process. We find that H2O formation from chemisorbed O and H atoms is a highly activated process. The largest barrier along this route, with a value of approximately 1 eV, is the addition of the first H to O to produce OH. Once formed, however, OH groups are easily hydrogenated to H2O with a barrier of approximately 0.2 eV. Disproportionation reactions with 1:1 and 2:1 stoichiometries of H2O and O have been examined as alternative routes for OH formation. Both stoichiometries of reaction produce OH groups with barriers that are much lower than that associated with the O + H reaction. H2O, therefore, acts as an autocatalyst in the overall H2O formation process. Disproportionation with a 2:1 stoichiometry is thermodynamically and kinetically favored over disproportionation with a 1:1 stoichiometry. This highlights an additional (promotional) role of the second H2O molecule in this process. In support of our previous suggestion that the key intermediate in the low-temperature H2O formation reaction is a mixed OH and H2O overlayer we find that there is a very large barrier for the dissociation of the second H2O molecule in the 2:1 disproportionation process. We suggest that the proposed intermediate is then hydrogenated to H2O through a very facile proton-transfer mechanism.     

钴铜铝水滑石类化合物的合成及其催化氧化对甲酚：Ⅱ.对甲酚的催化氧 …

考察了前文制得的水滑石及其焙烧产物在对甲酚氧化反应中的催化性能，发现经水滑石焙烧得到的具有尖晶石结构复合氧化物比没有焙烧的具有水滑石结构的以及由经物机械混合的样品具有更高的活性。     

Catalytic, asymmetric synthesis of siphonarienal.

This paper describes the synthesis of the marine natural product, siphonarienal. The key step of this synthesis is an aldol reaction that constructs most of the skeleton and sets all three stereocenters of the target in one step from commercially available starting materials. Deoxygenation and chain homologation steps complete the synthesis.     

Study of plant coumarins: XIV. Catalytic amination of 7-hydroxycoumarin derivatives

Catalytic amination of 7-hydroxy-6-cyanocoumarin or 7-hydroxy-6-methoxycarbonylcoumarin triflates with substituted anilines, isoquinolin-5-amine, 1H-pyrazol-3-amine, or amino acids of penicillin series affords the corresponding 7-(N-substituted) aminocoumarins. In the amination of the mentioned triflates and also of peuruthenicine tosilate with 2-(piperidin-1-yl)aniline the catalytic system Pd(OAc)₂-BINAP has been efficient.     

Catalytic phosphorylation of polyfluoroalkanols. 15. Catalytic phosphorylation of α-polyfluoroalkylbenzyl alcohols by bis(polyfluoroalkyl) chlorophosphates

The catalytic phosphorylation of -polyfluoroalkylbenzyl alcohols by bis(polyfluoroalkyl) chlorophosphates is a convenient method for the synthesis of various bis(polyfluoroalkyl)(-polyfluoroalkylbenzyl) phosphates, including those having donor substituents in the benzene ring. It was shown that in the series of p-methyl--trifluoromethylbenzyl phosphates p-CH₃C₆H₄CH-(CF₃)OP(O)XY (where X, Y=Cl, CF₃CH₂O), the ability to act as O-alkylating agents with respect to polyfluorinated alcohols is a common characteristic, and the alkylating ability increases symbatically with increase in the overall electron-acceptor strength of the X and Y substituents at the phosphorus atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 878–886, April, 1990.     

Saturated nitrogen-containing heterocycles. 16. Catalytic synthesis of N-arylperhydroacridines

Catalytic hydroamination of methylene-2,2-dicyclohexanone in the presence of substituted anilines or nitrobenzenes involves the formation of N-arylperhydroacridines. The stereoisomeric composition and yields of the latter are determined by the nature and position of the substituent in the aromatic ring of the aminating agent. The structure of isomeric N-arylperhydroacridines was established from data of ¹³C NMR spectroscopy and x-ray diffraction analysis.For Communication 15, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1094–1100, August, 1993.     

Catalytic phosphorylation of polyfluoroalkanols Communication 10. Catalytic phosphorylation of α-polyfluoroalkylbenzyl alcohols by diaryl chlorophosphates

Conclusions Irrespective of the structure of the alcohol and the reaction conditions, catalytic phosphorylation of -polyfluoroalkylbenzyl alcohols by diaryl chlorophosphates leads exclusively to -polyfluoroalkylbenzyl diaryl phosphates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 878–882, April, 1985.     

Catalytic processes on membrane palladium alloys: I. Carbon monoxide disproportionation

The results of a kinetic study of the disproportionation reaction of carbon monoxide on the surface of B1–B3 palladium alloy membranes over wide ranges of residence times and temperatures are reported. The specific rates and activation energies of the reaction with the formation of CO₂ and atomic carbon adsorbed on the surface were determined. It was found that the rate of reaction on all of the alloys from the B series other than B3-2 was independent of the consumption of CO and the residence time. The catalytic activity of multicomponent palladium alloy membranes in the CO disproportionation reaction was much lower and the activation energy was higher than the corresponding parameters of Pd-(6–10)Ru and Pd-5.5Ni binary alloy membranes. Atomic carbon formed in the reaction on all of the alloys from the B series other than the B3-2 alloy did not form carbon deposits as polymer films, pyrolytic carbon, or soot strongly bound to the surface of each other to result in a decrease in the rate of reaction. On the surface of the B3-2 alloy, atomic carbon initiated the formation of a polymer film weakly bound to the surface, which decreased the rate of reaction. A reaction mechanism was proposed to adequately describe the experimental results.     

Catalytic asymmetric hydrosilylation of ketones: I. Chiral phosphine-platinum(II) complex-catalyzed hydrosilylation.

Dichlorobis(dimethylphenylphosphine)di-μ-chlorodiplatinum(II) was found to be an effective catalyst for the hydrosilylation of alkyl phenyl ketones with methyldichlorosilane to give the corresponding silyl ethers of 1-phenylalkanols. In the case of dialkyl ketones, the reaction was accompanied by formation of silyl enol ethers in considerable amounts. Asymmetric hydrosilylation of a series of alkyl phenyl ketones catalyzed by chiral phosphine- platinum(II) complexes was undertaken. The products were readily converted into partially active 1-phenylalkanols.